Oil-fired Forced Air

Oil-fired Forced Air
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Cat. No. M144-60/2011E (Print)
ISBN 978-1-100-19263-5
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Aussi disponible en français sous le titre : Le chauffage au mazout
Revised February 2012
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Heating with Oil
Produced by
Natural Resources Canada’s Office of Energy Efficiency
The Heating and Cooling series is published by Natural Resources
Canada’s Office of Energy Efficiency. EnerGuide is the official
Government of Canada mark associated with the labelling and
rating of the energy consumption or energy efficiency of household
appliances, heating and ventilation equipment, air conditioners,
houses and vehicles. EnerGuide also helps manufacturers and
dealers promote energy-efficient equipment and provides
consumers with the information they need to choose
energy-efficient residential equipment.
Natural Resources Canada’s Office of Energy Efficiency promotes
the international ENERGY STAR symbol in Canada and monitors
its use. Major manufacturers and retailers of energy-efficient
products, utilities and energy retailers, and interest groups from
Australia to Europe, recognize the benefits of ENERGY STAR for
consumers and have joined in promoting the symbol.
ENERGY STAR is the international symbol of premium energy
efficiency. Products that display the ENERGY STAR symbol have
been tested according to prescribed procedures and have been
found to meet or exceed high energy efficiency levels without
compromising performance.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
1. Making decisions about home heating . . . . . . . . . . . 10
2. Basic heating equipment for oil-fired systems . . . . 21
3. Furnace efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4. Comparing annual heating costs . . . . . . . . . . . . . . . . . 42
5. Buying, installing or upgrading a system . . . . . . . . . 48
6. Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
7. Domestic water heaters . . . . . . . . . . . . . . . . . . . . . . . . . 59
8. More information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
If your present home heating system is costing too much to operate,
is in poor condition, or if you are planning to buy a new home,
you are probably considering your heating options. Approximately
60 percent of the energy required to run the average home is used
for space heating.
One of the most important projects you will undertake as a
homeowner, along with insulating and air sealing, is choosing,
changing or modifying your heating system. A wise decision about
heating can significantly reduce the cost of running your home and
make it more comfortable. Some impressive improvements have
been made in heating systems in recent years, and there is a wide
range of good equipment on the market.
You will be using your new or improved heating system for a long
time, so that it’s important to do your homework before you make
a choice. It’s worth taking the time now to ensure that you make
the best choice for your situation.
You should thoroughly investigate all your options. These days,
however, your options may be quite bewildering because of the wide
range of equipment and energy sources available. This booklet will
help you in your decision-making process. It will be useful whether
you are installing a system in a new home, replacing a system in an
existing home or considering upgrading your present system.
How to use this booklet
To simplify the process of choosing a heating system, we have identified
five interrelated steps for making your home-heating decisions.
Step 1: Getting started
Step 2: Draft proofing and insulating
Step 3: Selecting an energy source
Step 4: Selecting or improving the heat distribution system
Step 5: Selecting the heating equipment
These steps and various options are discussed in Chapter 1. The
remainder of this booklet focuses on the oil heating option.
Natural Resources Canada (NRCan) also produces other booklets
available at oee.nrcan.gc.ca/infosource which might be of interest to
you. See page 64 for more information.
How you use this booklet is determined, in part, by where you are
in your decision-making process.
• Ifahouseisbeingbuiltforyou,youmayhaveallthestepsand
options open to you (Steps 2 through 5).
• Ifyoualreadyownyourhomebutareconsideringreplacingan
existing heating system, many of the steps and options may be
available if you have a variety of fuel and energy choices in your
area (Steps 2 through 5).
• Ifyourexistingheatdistributionsystem(forced-airorhydronic)
is satisfactory, and you only want to upgrade it (Step 4) to
reduce your heating bill, your options are switching energy
sources (Step 3), selecting higher-efficiency equipment, or
upgrading and adding equipment to your current furnace or
boiler (Step 5). You may also decide to insulate and draft-proof
(caulk and weatherstrip) your house (Step 2).
• Evenifyouaresatisfiedwithyourexistingheatsource,you
should look at Steps 2, 4 and 5.
Before proceeding, you should become familiar with basic concepts
that will help you understand your options.
Heating concepts
Energy efficiency
All fuel-burning systems (oil, natural gas, propane, wood) lose
heat because of
– transient operation
– cold start-up
– incomplete combustion
– warm house air being drawn up the chimney
Heating concepts (continued)
The extent of these losses determines the efficiency of the
furnace or boiler. The efficiency is measured as a percentage that
indicates the amount of the original heat that warms the house.
Steady-state efficiency measures the maximum efficiency
the furnace achieves after it has been running long enough to
reach its peak-level operating temperature. A service person
uses this important standardized test to adjust the furnace, but
the measurement it gives is not the efficiency that the furnace
or boiler will achieve in actual use over a heating season. The
difference between the test result and actual use is much like
the difference between the very low fuel consumption figures
for highway driving published for cars and the actual fuel
consumption of the car in day-to-day service.
Seasonal efficiency takes into consideration not only normal
steady-state operating losses up the chimney but also several
other losses, such as the use of heated house air for combustion
and dilution processes. Seasonal efficiency also considers the
fact that most furnaces rarely run long enough to reach their
steady-state efficiency temperature, particularly during milder
weather at the beginning and end of the heating season, as well
as the loss of heat from the appliance when it is not running.
The seasonal efficiency expressed as annual fuel utilization
efficiency (AFUE) is useful to a homeowner. It is a good
indication of how much the annual heating costs will be reduced
by improving existing equipment or by replacing it with a
higher efficiency unit (see Table 1, page 43). However, the AFUE
does not consider the electricity used by the appliance to run
blowers, fans, pumps, etc.
Design heat load is an important component in calculating the
required size of heating equipment.
Many variables go into determining the design heat load of
a house, including two temperature design conditions: the
inside and outdoor design temperature. The inside design
temperature is the temperature at which most occupants
would be comfortable, and is typically 20°C. The outdoor
design temperature represents the probable coldest outside
temperature that the heating system will have to supply heat
against to keep the inside temperature at the proper level – this
varies by climatic region across the country.
Heating concepts (continued)
In winter, heat transfers from inside to the outside, and this
transfer of heat is measured in British thermal units (Btu) or
megajoules (MJ). How fast this heat is lost to the outside will
depend upon the difference between the inside and outside
temperatures. The greater the temperature difference, the faster
the heat loss. The rate at which this heat transfers is called the
heat loss and is measured in Btu per hour (Btu/h) or MJ/h. Your
heating system needs to be sized to produce enough heat to
maintain the interior design temperature at 20°C when the
outside temperature reaches the outdoor design temperature.
The annual heating load is the number of litres, gigajoules, etc.
required to heat the house over the entire heating system.
If you are heating with oil or are considering doing so, the more
you understand the terminology associated with oil-heating
systems, the better equipped you will be to make a wise heating
system choice. See the text box “Oil heating terms” for basic terms.
Oil heating terms
Fuel oil
The petroleum industry produces several grades of fuel oil,
but only one is commonly used for most home heating. This is
Number 2 fuel oil, and it must meet government and industry
standards for density, viscosity and heat content. In colder
regions, Number 1 fuel oil, which is a slightly lighter fuel, is used.
Measuring up
The heating (bonnet) capacity of oil-heating appliances is the
steady-state heat output of the furnace, commonly measured
in British thermal units per hour (Btu/h). One Btu is equal
to the amount of energy it takes to raise the temperature of
one pound of water by one degree Fahrenheit. Most oil-fired
central heating appliances being sold for home use today
have heating capacities of between 56 000 and 150 000
Btu/h (59 to 157 MJ/h). One litre (L) of Number 2 fuel oil
contains approximately 38.2 MJ (36 500 Btu) of potential heat
energy. Heating capacity is also expressed in megajoules per
hour (MJ/h).
Oil heating terms (continued)
The heating capacity of electric heating systems is usually
expressed in kilowatts (kW). A kilowatt hour (kWh) is the
amount of electrical energy supplied by 1 kW of power over a
one-hour period.
Certification and standards
All fuel-burning furnaces, boilers and other combustion
equipment sold in Canada must meet strict manufacturing
and installation standards established by such organizations as
the Canadian Standards Association (CSA), the Underwriters
Laboratories of Canada (ULC) and the International Approval
Service, Inc. (IAS). These independent bodies set standards
and test for safety and performance. Before purchasing your
heating equipment, be sure it carries a CSA, ULC, Canadian
Gas Association, IAS or Warnock Hersey certification label.
Since 1998, Canada’s Energy Efficiency Regulations have
required that oil furnaces achieve at least 78 percent AFUE.
Since September 2010, oil boilers must have a minimum
efficiency level of 84 percent AFUE (see page 20 for more
information on energy efficiency standards). Also, a new standard
proposed for September 2012 will require that oil boilers be
equipped with a water temperature controller that automatically
adjusts the temperature of the water as the load varies. (See
page 32 for more information on water temperature controllers).
Regardless of how you are heating your home currently, you can
probably improve the efficiency of the heating system. Some
improvements are simple enough for you to do them yourself.
Others require the services of a licensed service person, a qualified
heating contractor or an electrician. All improvements should be
effective and pay for themselves in a reasonable period. When you
consider your heating system, remember also to consider your hot
water situation.
This chapter explains a five-step process that will help you make
wise decisions about home heating.
Step 1: Getting started
Consider getting expert advice by having an energy retrofit
evaluation done. The service includes an evaluation of your home
and provides recommendations or a written report and an energy
efficiency rating for your home. The evaluation will help you plan
the energy upgrades that can easily be incorporated cost-efficiently
into most renovation projects, resulting in a more comfortable
home that uses less energy. For additional information, or to find
a delivery agent in your area, visit the Office of Energy Efficiency’s
(OEE’s) Web site at oee.nrcan.gc.ca or call NRCan toll-free at
Step 2: Draft proofing and insulating
Before you invest in a new or improved heating system, check the
efficiency of the house envelope to determine if the house needs
more insulation or has many air leaks. Determine where you can
draft-proof and insulate simply and effectively before you have the
heating system sized, installed or upgraded.
Draft-proofing and insulating have many advantages. Heating the
house will cost considerably less, and you will be more comfortable
because of fewer drafts and warmer surfaces, such as walls. Your
house will tend to be cooler in the summer, too.
Humidity levels will improve as well. Dry air in a house during
the winter is caused by too much outside air getting in. Although
the relative humidity may be high for cold outside air, the absolute
amount of moisture (water vapour) that cold air can hold is actually
very low. When this cold, dry air is brought inside and heated to
room temperature, it becomes extremely dry.
If the air inside your house feels too dry, one of the simplest
solutions is to add moisture by using a humidifier or an evaporator
tray. However, the best way to increase humidity levels (and lower
heating costs) is to reduce air leakage. In general, most houses that
have been air tightened do not need a humidifier – the moisture
generated through cooking, bathing, dishwashing and other
activities is sufficient.
However, with an airtight house the reverse can occur. Making your
house more airtight can affect the air quality inside. Unwanted
fumes, odours, gases and too much humidity can be trapped inside
the house envelope and build up over time to unpleasant levels.
One of the best ways to solve this problem is to install a fresh
air intake or a mechanical ventilation system that brings in and
circulates fresh air without causing drafts.
Often, the most energy-efficient way of doing this is by using
a heat-recovery ventilator (HRV). An HRV consists of two airhandling systems: one collects and exhausts stale indoor air; the
other draws in outdoor air and distributes it throughout the home.
An HRV provides fresh air at a reduced cost while also saving
energy by reducing the heating (or cooling) requirements (see
page 45). Contact your service person for more information.
Insulating, caulking and weatherstripping will reduce the amount of
heat needed to keep your house comfortable. If your existing home
has not been thoroughly reinsulated and draft proofed, you should
consider doing this before changing or modifying the heating system.
For more information about draft proofing and insulating, write for
a free copy of Keeping the Heat In (see page 64). Whether you plan
to do the work yourself or hire a contractor, this publication explains
the details and can help make the entire job easier.
To ensure that you get a heating system with the right heating
capacity, be sure to draft proof and insulate before you and your
contractor determine what size of heating system and equipment is
best. In general, oversized furnaces will waste fuel because they tend
to operate in frequent, short cycles. They may also decrease comfort
because of the resulting excessive temperature fluctuations.
If you are building a new house, remember to find out which
energy efficiency upgrades you should consider including in your
building plans. Also, look for homes that have been evaluated
through a program such as ENERGY STAR® for New Homes. The
ENERGY STAR® for New Homes initiative helps you to identify
homes that are significantly more energy-efficient than those built
to minimum building code requirements. The increased energy
efficiency of these homes translates into reduced energy costs for
their owners.
ENERGY STAR® for New Homes is currently available in many
regions across Canada and is delivered in the field by a network
of regional service organizations. If you want to buy or build an
ENERGY STAR qualified new home, contact an ENERGY STAR®
for New Homes service organization in your area to schedule an
evaluation of your building plans. Visit www.newhomes.gc.ca for
more information.
Step 3: Selecting an energy source
The next step is to select the heating energy source that is right
for you. Generally, your options include oil, natural gas, propane,
electricity or wood. You may also choose a combination of these
conventional energy sources or alternatives, such as solar energy.
Your decision regarding the most appropriate energy source should
be based on several considerations, the most important of which are
described here.
Energy availability
Not all energy sources are available in all areas of Canada. Heating
oil and electricity are generally available in most places, but natural
gas, which must be delivered by pipeline, may not be available in
many rural and remote areas. Propane is available in most parts of
Canada and may be used in rural or cottage areas as a substitute
for fuel oil or natural gas although, often, at a significantly higher
operating cost. In many areas, wood is a cost-effective complement
to your conventional heating system. Check with your local fuel
supplier or electrical utility to find out which energy sources are
available in your area.
Cost considerations
For most homeowners, a major factor in the home-heating decision
is cost. This factor will have two major components – the capital
cost of the installed heating system and the annual operating cost
for energy. Other factors, such as maintenance costs, cleanliness and
noise of operation, should also be considered.
Installation costs of various heating systems, depending on
whether they are new or retrofitted, include such items as
• storagetankforoilorpropane
• newormodifiedventingsystem
• connectiontogaslinesorelectricpowerlines
• costof200-ampereserviceforelectricheating
• heatingequipment(furnace,boiler,replacementburner,
baseboard heaters, heat pump, ducting system or pipes
and radiators)
• thermostatsandcontrols
• trenchingordrillingforearth-energysystems(ground-source
heat pumps)
• labourforinstallationofanyoftheabove
The capital cost of a heating system can range from as low as
$1,000 for baseboard heaters in a small house to as high as $20,000
or more for a ground-source heat pump capable of providing
heating, air conditioning and hot water for a larger home. Heating
contractors or utility representatives can give you an estimate of the
capital cost of various systems. Always ask for a firm quote before
you authorize any work.
The operating or fuel cost of a heating system is determined by
the following three major factors.
• Annual heating load or heating requirements of the house. The
heating requirements depend on climate, size and style of
the house, insulation levels, airtightness, amount of useful
solar energy gained through windows, amount of heat given
off by lights and appliances, thermostat setting and other
operational factors. Together, these factors determine how much
heat must be supplied by the heating system over the annual
heating season. This number, usually expressed as Btu, kWh
or MJ (see pages 8 and 9 for a definition of these terms), can
be estimated by a heating contractor, home builder or utility
• Choice of energy source and its unit price. Each energy source is
measured and priced differently. Oil and propane are priced in
cents per litre (¢/L); natural gas in cents per cubic metre
(¢/m3), dollars per megajoule ($/MJ) or dollars per gigajoule
($/GJ); electricity in cents per kilowatt hour (¢/kWh); and wood
in dollars per (face) cord. You must consider the heat content of
the various energy sources to determine the most cost-effective
energy source for your area. Contact your local utility or fuel
supplier for the price of energy sources. Table 2 on page 44 gives
the energy content for the various energy sources in the units in
which they are commonly sold.
• Equipment efficiency. The efficiency with which the appliance
converts the energy source to useful heat in the home is also an
important factor in the operating cost equation. For example,
if a furnace has an AFUE (see page 7) of 80 percent, then
80 percent of the heat value in the fuel is available. The other
20 percent is lost, mostly up the chimney so that additional fuel
must be consumed to make up for these losses. Improving the
efficiency of the heating equipment reduces energy use and cost.
The combination of heating load, fuel choice and equipment
efficiency determines the annual cost of heating. Chapter 4 has
a detailed description of how you can calculate heating costs for
various energy sources and technologies as well as typical seasonal
efficiencies (AFUE) for a range of technologies.
In the end, a homeowner considering a new heating system must
balance the capital cost against the operating cost and make the
best financial decision, taking into consideration how energy prices
might change in the future. Because annual operating costs (and
the differences in operating costs between different technologies)
are significant compared to capital costs, an investment in highefficiency equipment is often the wise choice.
The effects of energy production and consumption play an
important role in many of today’s key environmental problems.
Exploration and extraction of fossil fuels in fragile ecosystems, spills
and leaks during transportation, urban smog, acid rain and global
climate change – all can adversely affect our environment.
Each form of energy has a different impact at various points in the
energy cycle. Heating your home affects the environment in various
ways, from gases leaving the chimney to emissions at a coal-fired
electricity generating station, to flooding at a remote hydroelectric
site. While determining these impacts can be complex, it is
generally true that reducing the amount of energy you consume to
heat your home reduces the impact on the environment.
Step 4: Selecting or improving the heat
distribution system
Most heating systems today are either forced-air systems or
hydronic (hot water) systems. These consist of a heating unit
(furnace or boiler), a distribution system (ducts and registers,
or pipes and radiators), electric baseboards and controls (such
as thermostats) that regulate the system. Some houses use space
heaters and may not have distribution networks.
Forced-air systems
By far, the most common type of central heating system used in
Canadian homes is the forced-air system with a furnace as the heat
source. Among its advantages are its ability to provide heat quickly
and the fact that it can also be used to filter and humidify household
air. A forced-air system can also provide ventilation and central air
conditioning. In addition, the furnace fan can be used year-round
to provide continuous air circulation throughout the house while
efficiently distributing heat in colder months. You should consider
using a high-efficiency motor to reduce operating costs.
High-efficiency motors
Some residential furnaces have an option for a high-efficiency
motor. Most motor manufacturers have an option for an
electronically commutated brushless direct current (DC) motor
(high-efficiency). These high-efficiency motors may be referred to as
EC, ECM, BLDC or DC motors, depending on the manufacturer.
If you are purchasing a new furnace, you should consider buying
one that has a high-efficiency motor. An oil-fired furnace with a
high-efficiency motor is more efficient than an equivalent furnace
with a standard (permanent split capacitor [PSC]) motor. In homes
where the fan is run continuously or for extended periods, such
a motor can significantly reduce electricity consumption while
providing better air circulation. A brushless DC motor can reduce
average furnace electrical consumption by more than 70 percent
when used for continuous circulation. During the summer months,
a brushless DC motor also saves energy by reducing the load on
your air-conditioning system.
The actual electricity cost savings that you achieve will depend on
how often you use the central air circulation fan in the furnace.
If you have an existing furnace fitted with a PSC motor, you
can retrofit your furnace with an efficient brushless DC motor
at a reasonable cost to reduce electricity consumption. Retrofit
DC motors that connect to existing PSC motor connections
are available from most motor manufacturers. Talk to your local
installer or service person.
If your air circulation duct system has a high pressure drop of
200 pascals (0.8-inch water column) or more, a high-efficiency
brushless DC motor retrofit is not recommended. Talk to your local
installer or service person.
Forced-air heating systems also have some disadvantages. The
temperature of the air coming from the heating registers can vary
depending on the type of system. The air can sometimes feel cool
(especially with certain air source heat pumps) even when it is
actually warmer than the room temperature. The effect is similar to
the cooling action of a fan or a summer breeze. In addition, there
can be short bursts of very hot air, especially with oversized systems.
Some people may find these characteristics uncomfortable at times.
The ductwork that distributes the heat may transmit the noise of
the furnace and its circulating fan to every room and may circulate
dust, as well as cooking and other odours, throughout the house.
Consult your heating contractor for further information.
Hydronic heating systems
A hydronic heating system uses a boiler to heat water, which is
then circulated through the house before returning to the boiler to
be reheated.
Hot-water or steam-heating systems used to have large boilers and
used wrought-iron pipes and massive cast-iron radiators; some
of these still exist in older homes. For many years now, installers
have been using smaller copper piping, slim baseboard heaters and
smaller, more efficient boilers. CSA-approved non-metallic piping
is now available as an alternative to copper piping for space heating
and service hot-water distribution.
Other systems
Other home-heating systems that can be used independently or in
combination with the standard systems are also available. These
include room space heaters, radiant space heaters and built-in
radiant floor systems. Recently, boilers and other “hot water”
generators have been coupled with fan coils to provide a warm-air
heating system.
Room space heaters provide heat directly to the rooms they are
in and do not have a central heat distribution system. Examples
are wood stoves, freestanding gas fireplaces, vented oil-fired space
heaters and electric baseboard heaters.
Some space heaters can also be very effective radiant heat sources,
warming solid bodies, such as people, in their line of sight without
necessarily having to heat up all the air. Good examples are the new,
efficient, direct-vent gas fireplaces, advanced combustion wood
fireplaces, freestanding woodstoves, and portable electric infrared
radiant heaters. If properly located in a major living space, a radiant
space heater can actually act as an effective surrogate zoning system,
lowering the overall heat demands of the house and the final heating
bills while making the occupants feel more comfortable.
Built-in radiant floor systems are generally of two types: hot
water pipes in floors and electrical cables in floors, which may also
be installed in ceilings. The radiant floor type, which is becoming
increasingly popular, consists of narrow hot water pipes embedded
in the floor or laid in the joist space under the floor. Hot water at
a temperature of around 40°C (104°F) is pumped slowly through
the pipes and radiates heat into the house. Thick carpets can reduce
effectiveness significantly by acting as insulation. Such a system
may be more costly to install and does not appear to offer much in
direct energy savings. However, some radiant floor installations may
offer comfort benefits, resulting in lower thermostat settings and
reduced heating bills.
Your choice of heat distribution system may be limited if you have
a forced-air or hydronic system already in place. If you have an
electric baseboard heater and are faced with high heating bills, you
may want to change to another type of system and energy source,
even though it can be an expensive undertaking.
Although a major constraint is the lack of a distribution system,
many homeowners are finding that air ducts for a central forced-air
system or pipes and radiators for a hydronic system can be installed
at a cost that still makes the whole conversion financially attractive.
Fuel-fired space heaters, wood stoves and advanced, energy-efficient
wood or gas-fired fireplaces can also be effective.
Your choice will probably be based on the answers to the following
• Howmuchwillthesystemcostcomparedtoothersystems?
• Willthistypeofsystemsuitmylifestyle?
• WillIbecomfortablewithit?
• DoIwantcentralventilation,airconditioningoraircirculation?
• Isthereacontractoravailabletoinstallthesystem?
• Isthesystemcompatiblewithmyenergychoice?
Step 5: Selecting the heating equipment
After you have selected the energy source and heat distribution
system, you can begin to consider the alternatives for heating
equipment and efficiency levels. You will have to consider whether
to upgrade your existing heating equipment or to replace it entirely.
Several things can be done to improve the efficiency and general
performance of an existing heating system. You also have the
choice of several replacement models with various efficiency ratings
and prices.
The following are some details to consider when choosing your
Equipment efficiency and suitability
See Chapters 2 and 3 for a detailed discussion of your options for
oil furnaces and boilers.
Purchase, installation, operation and maintenance costs
Generally, the more efficient heating systems have a higher capital
cost. You must keep this in mind when considering any changes
or new equipment purchases. You want to make sure that the
reduction in energy consumption and enhanced comfort will
reimburse the improvement costs within a reasonable time. Most
often they will.
Often, the more efficient systems require much less house air for
combustion and dilution. Modifications to the existing venting
system may be required because some may not need a chimney but
can be vented out the side wall. This arrangement makes them safer
and more compatible with airtight housing. Finally, high-efficiency
heating equipment can be an additional marketing attribute if you
want to sell your house.
Servicing and guarantees
It is also important to know the causes for, and frequency of, servicing
your system, the price of parts, cost of servicing, and details of
guarantees and warranties, such as the period covered and whether
parts and labour are included. If you are uncertain about a particular
model, ask the seller to give you the names of people who have had
one installed.
Energy efficiency standards
The Government of Canada has implemented energy efficiency
standards for nearly all heating equipment and other energyconsuming appliances and products which are imported or shipped
for sale between provinces. Some provincial governments have
introduced energy efficiency standards as well. Generally, these
standards establish the minimum acceptable energy efficiency
for specific types of heating equipment. After the standards are
introduced, low-efficiency models that do not meet the standards
are no longer available on the market.
Energy efficiency rating system
The Government of Canada and the Heating, Refrigeration and
Air Conditioning Institute of Canada (HRAI) have established a
voluntary energy efficiency rating system for residential oil forcedair furnaces to help consumers compare the energy efficiency of
different products.
The EnerGuide label with the furnace’s AFUE rating (Figure 1)
is shown on the back page of manufacturers’ brochures. Included
on the EnerGuide label is a rating scale showing the range of
efficiencies for oil furnaces on the market as well as a pointer
indicating where the model is positioned compared with others in
terms of efficiency.
Chapter 4 shows you how to determine heating costs based on the
furnace’s AFUE rating.
An EnerGuide label for oil furnaces
As noted in Chapter 1, most oil-fired heating systems today are
either forced-air or hydronic systems. This chapter discusses the
equipment that makes up these two distinct systems.
Equipment for forced-air systems
Design and operation
Figure 2 illustrates a basic oil-fired, forced-air heating system.
This system consists of a burner fed by heating oil firing into a
combustion chamber in the furnace. The oil storage tank is usually
located in the house. The combustion gases pass through the
furnace, where they release heat across a heat exchanger. The gases
are then exhausted to the outside through a flue pipe and chimney.
For most systems, a barometric damper, acting as a valve in the flue
pipe, isolates the burner from changes in pressure at the chimney
exit by pulling varying quantities of heated room air into the
exhaust. A circulating fan passes cool house air from the cold air
return ducts over the furnace heat exchanger, where the air warms
up and then passes into the hot air ducts, which distribute the
heated air throughout the house.
Notice that there are two separate air movement paths. The first,
the combustion path, supplies air to the burner and follows the hot
combustion gases through the heat exchanger and flue pipe to the
chimney and out of the house. The combustion path also includes
dilution air drawn through the barometric damper. The second
path circulates and heats the air within the house.
In many houses, the quantity of dilution air drawn through
the barometric damper is much larger than that required for
combustion and can represent from 3 percent to 15 percent of
the heat loss in the house. Therefore, anything that reduces this
dilution airflow without compromising the performance of the
furnace will lead to increased fuel savings and efficiency.
Oil-fired forced-air furnace
Warm air
Cold air return
Flue pipe
Heat exchanger
gases out
air in
Burner fan
Air filter
Circulating fan
air in
Combustion chamber
Some new furnaces have an optional direct connection for using
outside air for combustion (sealed combustion) instead of using
indoor air. However, this method can have problems. On a cold
winter day, if the air is not warmed somewhat before it reaches the
burner, it can cool the fuel oil and cause start-up problems.
Maximizing effectiveness in forced-air heating systems
The performance of an existing forced-air heating system can be
improved in several ways.
Adjusting the furnace fan
In older, oil-fired furnaces, heat output from a forced-air system can
often be increased by adjusting the controls that turn the fan on
and off automatically. The fan controls are usually in a metal box,
on the front of the furnace, near the top. To remove the cover, you
must either squeeze it or remove some screws. Inside the box is a
temperature dial with three pointers (Figure 3): the lowest setting is
the fan OFF pointer; the next is the fan ON setting; and the third
and highest pointer is the safety limit control that shuts the burner
off if the furnace gets too hot. This safety limit is normally set at
the factory. Do not adjust the safety limit setting.
Circulating fan control
Fan on
Fan off
The ON and OFF fan control pointers are usually set for an
ON temperature of 66°C (151°F) and an OFF temperature of
49°C (120°F). To increase the amount of heat taken from the
furnace, most heating experts now recommend changing the ON
temperature to 49°C (120°F) and the OFF temperature to 32°C
(90°F). These changes make the fan come on sooner after the
burner starts up and stay on longer after it shuts down, allowing the
circulating air to extract more heat from the furnace and lose less
heat up the chimney or through the vent.
The fan control dial is spring-mounted, so you must hold it firmly
with one hand while you adjust the pointer with the other. After
you replace the cover of the metal box, ensure the “auto/manual”
switch is set to auto. If you feel uncomfortable or unsure of what
to do to modify these settings, ask your furnace service person
to make the setting changes for you.
These changes may result in slightly lower air temperatures
from the registers at the beginning and end of the furnace cycle.
If the cooler air at either end of the furnace cycle makes you feel
uncomfortable, try raising the fan ON setting to 54°C (129°F) or
the fan OFF setting to 38°C (100°F), or try both.
A two-speed fan will allow you to get even more heat out of the
furnace while providing for continuous air circulation and more
even temperatures throughout the house while the furnace is off.
However, using this fan will increase your electricity bill.
As mentioned previously, some of the new high-efficiency furnaces
use a more efficient, variable-speed, brushless DC (often called
ECM) motor to run the circulating fan. The speed of the fan
depends on the heat demand. For extended or continuous fan
operation, such a unit can save a significant amount on your
electricity bill while making the delivery of heat more even and
Getting the heat where you want it
Uneven heat distribution is sometimes a problem, which results
in the inability to heat some rooms in the house, such as upstairs
bedrooms. This problem can be caused by warm air leaking
through the joints of the heating ducts or heat loss from ductwork
passing through the basement or through unheated areas such
as a crawl space, an attic or a garage. When the circulating fan is
running, the rate of heat loss can increase significantly if leaky ducts
are in an exterior wall, an attic or a crawl space. This is one more
good reason to ensure all the ducts are well sealed.
Sealing all joints in the ductwork with a water-based duct
mastic (sealant) will reduce or eliminate warm air leaks. Hightemperature duct tape may seal the joints but it tends to degrade or
permit air leakage over time.
You should seal ducts that pass through an unheated area such as
a crawl space or an attic, then wrapped them with batt or duct
insulation. Do the same for long duct runs in the basement. It is
recommended that the warm air plenum and at least the first three
metres (10 feet) of warm air ducting be insulated as a minimum. A
better practice is to insulate all the warm air ducts you can access.
Use batt insulation with foil backing, or enclose the insulated ducts
in the joist space.
If your basement is presently heated by the heat loss from the ducts,
you may need to install additional registers there after you insulate
the ducts. Adding the registers will ensure that the heat will be
going only where you want it, when you want it, without being lost
along the way.
Rooms that are on upper floors or far from the furnace are
sometimes difficult to heat because of the heat losses described
above and also because of pressure losses from friction and other
restrictions to airflow (such as right-angle bends) in the ductwork.
This problem can sometimes be corrected by slight modifications to
the ductwork after the ducts have been sealed and insulated and by
balancing the dampers in the supply ducts (Figure 4) to redirect the
airflow from the warmer areas to cooler areas.
Balancing damper in the supply duct
Warm air
supply duct
In some forced-air distribution systems, balancing dampers may
be located in the secondary warm air ducts, close to where they
branch off from the rectangular main heating duct. Often, the
balancing dampers can be identified by a small lever on the outside
of the duct, as shown in Figure 4. The position of this lever (or,
sometimes, a slot in the end of the damper shaft) indicates the angle
of the unseen damper inside the duct. If there are no such dampers,
you will have to use the ones in the floor registers.
Start by closing the dampers in the ducts that supply heat to the
warmest rooms (even if completely closed, they will still supply
some heat to these rooms). Wait a few days to see what effect this
has on the overall heat balance, then make further adjustments as
necessary. Such adjustments may reduce slightly the total airflow
through the furnace, but this will be balanced to some extent by a
slight increase in the temperature of the delivered air.
However, you should be careful about making adjustments yourself.
It may be more practical to have a trained service technician do the
adjustments. If you reduce the airflow too much, you could cause
an undesirable rise in the temperature inside the furnace plenum.
It is a good idea to have this furnace temperature rise checked by a
furnace service person.
Most houses have inadequate cold air returns, which results in
insufficient airflow through the furnace. Putting additional cold air
returns in the living area, particularly in the bedrooms, can improve
air circulation and heating system efficiency while also improving
comfort and air quality in the house.
Dangerous and incorrect methods: An incorrect method for
solving the problem of too few cold air returns has been to open
the cold-air return ductwork or the plenum in the basement area
near the furnace or to remove the furnace access panel near the
air filter. These methods are dangerous. The depressurization
caused by the circulating fan can disrupt the combustion and
cause spillage or backdrafting of combustion products. These
combustion products can then be circulated through the house
instead of exhausting through the chimney. In certain cases, this
can cause carbon monoxide (CO) poisoning.
If stubborn heat distribution problems cannot be corrected by
damper adjustments and other duct modifications, have a qualified
serviceperson do a complete balancing of your distribution system.
Automatic setback thermostats
The easiest way to save heating costs is to lower the
temperature setting on the house thermostat when possible.
An automatic setback thermostat will adjust your home’s
temperature automatically. These thermostats have a
mechanical or electronic timer that allows you to set household
temperatures for specific periods of the day and night. As a
general rule, you will save 2 percent on your heating bill for
every 1°C you turn down the thermostat overnight.
You could program the thermostat to reduce the temperature
a short while before you go to bed and to raise it again before
you get up in the morning. For very well-insulated houses,
you might well extend these delays even more. You could also
program it to reduce the temperature for any period during
the day when the house is unoccupied and to restore the
temperature shortly before you return. A good guide is to have
the temperature set at 17°C (63°F) when you are sleeping or not
at home and at 20°C (68°F) when you are awake and home.
Experiment with the thermostat until you find the most
comfortable and economical routine for your family.
If you have a hydronic (hot water) system, you can also reduce
energy use through zone control. In this system, thermostatcontrolled valves on each radiator permit the control of
individual room temperatures. A plumbing and heating
contractor can provide more information about zone control
and can install the required equipment when the heating system
is installed.
Hydronic systems respond much more slowly than warm air
systems. Therefore, to achieve savings with thermostat cutback,
you must turn the thermostat down long before you go to bed
and have it automatically turn up long before you get up in
the morning.
Zone controls are also available for forced-air heating systems,
usually with dampers in main duct passages driven by separate
thermostats in different areas of the house, although zoning is
much less common in hydronic systems.
Automatic setback thermostats (continued)
Improved thermostats
More sophisticated electronic and self-tuning thermostats are
also being developed. These are very sensitive and help reduce
the temperature “swing” from an average range of 1.5° to 2°C
to 0.5° to 1°C, ensuring that the heating system turns on and
off as close to the required temperatures as possible. Energy
savings from these advanced mechanisms can vary, but comfort
is usually enhanced. However, in some cases, this may make
the burner cycle much more frequently, with a loss in efficiency,
and may compromise the integrity of your furnace or venting
system. In these cases, it may be worthwhile for you to purchase
a variable-speed motor. Instead of making frequent starts and
stops, it changes speeds.
Equipment for a hydronic (hot water)
heating system
Design and operation
A hydronic heating system uses hot water to distribute the heat
throughout the house and has the following three basic components:
• aboilertoheatthewater
• heatingunitsinmostrooms,usuallybaseboardsorradiators,
which are often located on an outside wall. Recently, radiant
floors have become a desired feature for new homes, where
relatively “cool” warm water at around 43°C (110°F) is
circulated through an array of pipes under the floor
• apumptocirculatethewaterfromtheboilertotheradiators
and back through a piping system
Oil-fired boiler
Flue pipe
inspection port
Oil burner
An oil-fired boiler (Figure 5) uses the same type of burner as an
oil-fired, forced-air furnace, although a boiler is often smaller and
heavier. There is no circulating fan and filter housing as there is in a
forced-air system. Instead, most boilers require a circulating pump
to push heat through the pipes and the radiator system, as shown
in Figure 6. The seasonal efficiency of old conventional hydronic
systems is similar to that of conventional forced-air systems, which
is approximately 60 percent.
Hydronic heating system
House radiator
Hot water
Expansion tank
Cold water
Drain cock
Maximizing effectiveness
The performance and efficiency of a hydronic heating system can
be improved in several ways.
Improving heat distribution
Old-fashioned gravity systems that circulate water or steam by
natural convection are much less efficient than systems that
have a circulating pump. Slow heat circulation may cause house
temperatures to fluctuate noticeably between firing cycles. It can
also take a long time to restore the house temperature after a
nighttime thermostat setback.
Moreover, a gravity system cannot circulate hot water to radiators
or baseboard heaters in basement living areas that are below the
level of the boiler. These problems can be overcome by adding a
circulating pump and replacing the open expansion tank with a
sealed and pressurized expansion tank near the boiler. If you have
a gravity system, discuss the possibility of upgrading it with your
plumbing and heating contractor.
Balancing the heat
Balancing the heat delivered to different areas of the house is as
important with a hydronic heating system as it is with a forced-air
heating system. Radiators are often fitted with a manual valve that
can control the amount of water flowing through them. Such valves
can vary the heat delivered to different rooms in the same way that
balancing dampers do in a forced-air heating system.
A thermostatic radiator valve (Figure 7) can be set to vary the heat
output automatically in any room. In the radiator valve system, the
water must pass through all the radiators, one after the other, on its
way back to the boiler. Therefore, this method does not work with
radiators or baseboard heaters installed in a “series loop” system.
If there is more than one loop in the system, some balancing of the
heat output can be achieved by adjusting the valves that control the
water flow through each loop. The heat output of baseboard units
can also be controlled to some extent by regulating the built-in
damper, which operates much like the damper in a warm air register.
Thermostatic radiator valve
Water temperature controllers
Conventional hydronic heating systems have the boiler water
temperature set at 82°C (180°F). A controller can reduce energy
consumption by adjusting the temperature of the circulating
water in relation to heating load changes. Outdoor temperature
is the primary variable in heat load. As it gets warmer outside, the
controller reduces the boiler water temperature to a level that will
maintain the design inside temperature. This is called “outdoor
reset control.” If the temperature is reduced too much on noncondensing boilers, corrosion can occur.
Homeowners can improve the efficiency of their heating systems
by investing in one or more of the improvements described in the
following section.
Upgrades and add-ons to basic oil
furnaces and boilers
Downsizing heat output and improving combustion are two
ways to upgrade a oil-fired heating system. Descriptions of these
approaches follow.
Downsizing heat output
Most residential oil furnaces or boilers manufactured before the
late 1970s have a cast-iron head burner. This kind of burner has a
relatively low seasonal efficiency of approximately 60 percent. If you
don’t know what type of burner you have, ask your service person.
There are four main reasons for this low seasonal efficiency: an
inefficient conventional burner; an inefficient furnace; air dilution;
or an oversized system.
Most heating systems in older homes are greatly oversized. As
well, homeowners have often added insulation, caulking, and
weatherstripping, and made other improvements, to reduce heat
loss and cut fuel consumption. As a result, the old systems are even
more oversized.
We know that an automobile gets much better fuel economy
when cruising on the highway than when continually starting,
accelerating and decelerating in the city. Like an automobile,
most oil furnaces perform best when running at their steady-state
condition, with the maximum stable flue gas temperature. But the
burner must run for between 7 and 20 minutes (min) to reach this
point, and some oversized units may never run long enough to get
there, even on the coldest days.
Ideally, the oil burner would run continuously when the outside
temperature is at the lowest temperature expected for your area,
or at what is called the “design temperature.” At that point, the
furnace would be operating close to the steady-state efficiency for
which it was rated. A running time of 45 to 50 min/h at your local
coldest design temperature is a practical goal. Discuss this concern
with your service person.
An oil heating system can be downsized just by replacing the oil
burner nozzle with a smaller one. Nozzles are rated in United States
gallons per hour with typical sizes of 1.1, 1.0, 0.85, 0.75, 0.65,
0.60 and 0.50. (1.0 U.S.gph = 140 000 Btu/h = 0.15 GJ/h).
With old cast-iron head burners, you should be careful not to
reduce the firing rate too much because that will cause incomplete
combustion and reduced furnace efficiency. If you have such a
burner, you should consider reducing the nozzle only one size. In
any case, with a conventional burner, the nozzle size should not be
reduced below the minimum firing rate given on the manufacturer’s
rating plate.
Many old oil furnaces have been retrofitted with a flame-retention
head burner, which has improved their seasonal efficiency. Most
oil furnaces and boilers installed in the past 15 to 20 years will
have a flame retention head burner as standard equipment. With
a flame-retention head burner (see Figure 8), the nozzle size can
be reduced significantly, as good combustion performance can be
maintained; the lower limit on the firing rate is governed by the
flue gas temperature leaving the furnace. In general, you should
maintain a furnace exit temperature above 204°C (400°F) if you
have an outside chimney and 177°C (350°F) if you have a chimney
inside the house. The proper nozzle size for your house and heating
needs can be determined by your service person.
Improving combustion system performance
Several relatively straightforward things can be done to improve
combustion performance and the efficiency of an existing oil-fired
furnace or boiler.
Install a flame-retention head burner or a high-static burner
The performance of an oil-fired heating system depends, to a large
extent, on how well air and fuel oil are mixed in the burner, a
function performed by the atomizing spray nozzle that mixes air
and fuel into a combustible mist.
Flame-retention head burner
Control box
Fuel line
Air control
Flame-retention head
solenoid valve
Compared to the old cast-iron head burner, a flame-retention
head burner does a much better job of mixing air and fuel. This
efficiency reduces the amount of air required for good combustion.
The result is a narrower, hotter flame from the same amount of fuel
(see Figure 9, page 36).
Flame-retention head burners are now standard on new furnaces and
can also be added to most older furnaces. Contact an oil service firm
or fuel supplier to discuss a flame-retention head for your system.
High-static burners
New burners which have advanced combustion heads that operate
at high-static pressure can run at even lower excess air levels
than previous models. The increase in efficiency can be close to
20 percent.
As well, the high-static burner is powerful and can overcome
pressure fluctuations generated at the vent termination and produce
a stable flame even under adverse weather conditions. The pressure
drop across the burner head also stops heated house air from
flowing through the burner, combustion chamber and furnace,
and out the chimney during the furnace off-cycle.
The high-static pressure makes the burner almost completely
unaffected by depressurization within the house, which is a good
quality to have in an airtight home. The high-static burner can also
run as a sealed combustion unit.
Because of the many advantages of a high-static burner, it is
recommended that any new furnace or boiler you buy be equipped
with one.
Venting an increased-efficiency appliance
You should have a technician inspect your chimney if you replace
the burner with a flame-retention head or a high-static burner,
or replace your furnace or boiler to increase the efficiency of your
existing system.
If it is a masonry chimney located on the outside wall of your house,
it is probably too big for the amount of gases that will be going
through it now. The flue gases can cool and condense in the chimney,
causing the brick to deteriorate over time. Installing a stainless steel,
double-walled flue pipe from the furnace to the chimney and/or a
stainless steel liner in the chimney can prevent condensation from
forming. Also, these changes can reduce the chimney draft and
improve the overall performance of your heating system.
Install a delayed-action solenoid valve
An oil-fired heating system wastes heat if incomplete combustion
causes a heavy layer of soot to form on the inside of the heat
exchanger. Using a flame-retention head burner reduces the amount
of incomplete combustion. However, a significant amount of soot
can still be produced at the beginning and end of each firing cycle,
which can also leave the smell of oil in the house.
You can dramatically reduce, and even eliminate, soot formation
and the associated odours by installing a delayed-action solenoid
valve on the burner between the oil pump and the burner nozzle
(see Figure 8, page 34).
Flame patterns with different burner heads
Flame with Conventional Cast-Iron Head Burner
Combustion Chamber
Conventional cast-iron head
Fuel line
Blast tube
Flame with Flame-Retention Head Burner
Combustion Chamber
Flame-retention head
Fuel line
Blast tube
Furnace efficiency
Since the fuel price scare of the early 1970s, the industry has been
working to improve the efficiency of furnaces and boilers. The
introduction of improved burners with flame-retention heads
was the first major step in boosting the efficiency of conventional
oil-fired heating equipment. The high-static burner, which has
recently come onto the market, has further enhanced the efficiency
capability of heating systems.
Manufacturers have produced a “mid-efficiency” class of oil furnace
that uses the new high-static burners. As well, they have developed
a condensing furnace that cools the combustion gases enough to
recover the heat that is normally lost in the form of water vapour.
New technologies are allowing appliances to integrate efficiently
two functions, such as space and water heating, simultaneously.
Several oil-fired systems that are vented directly out the side wall of
the house, thereby eliminating the need for a chimney, have been
approved in Canada.
Mid-efficiency oil furnace
Another non-condensing, mid-efficiency furnace (Figure 10)
features an improved low-mass combustion chamber (usually
ceramic fibre) and passes the hot combustion gases through a heat
exchanger that enables the circulating house air to extract more
heat. In the most efficient designs, the barometric damper is not
needed and it is not necessary to dilute exhaust gas with house air.
A mid-efficiency furnace must keep the exiting gases above a
certain temperature to prevent water vapour in the flue gas from
condensing inside the furnace or venting system, where it can cause
corrosion and other serious problems. The exit temperature of the
combustion gases can be as low as 150°C (302°F).
Some of the new oil-fired equipment can be vented directly though
the side wall of the house without using a chimney.
One side wall-venting type uses the forced draft of a highstatic burner to expel combustion gases. Others also use sealed
combustion with a high-static burner.
Another side wall-venting system uses an additional induced draft
fan, normally mounted downstream of the furnace on the inside
wall of the house. This fan pulls the gases from the furnace out of
the house through an exhaust vent. Some of these sidewall systems
require dilution air from the house or have a long run time after
the burner shuts off to purge the furnace system of any combustion
gases. The last two types reduce efficiency.
Mid-efficiency oil furnace
Cool air
Heat exchanger
Warm air
flue pipe
(no barometric
Fan control
Air filters
Combustion chamber
The benefits of a good mid-efficiency furnace are
• muchlowercombustionanddilutionairrequirements
• morepowertoexhaustthecombustionproducts(anadvantage
in newer, more airtight, housing)
• asafetyshut-offincaseofdraftproblems
• amoreeffectiveventingsystem
Mid-efficiency furnaces may have a seasonal efficiency of 83 percent
to 89 percent and may use 28 percent to 33 percent less fuel than an
old conventional furnace that produces the same amount of heat.
Heating industry experts believe that new technology furnaces,
small enough to fit the needs of even super-insulated houses, will
be the next major development in oil heating. This innovation can
come about in two ways – by developing alternative technology for
oil burners or by integrating the functions of various home energy
requirements, such as space and water heating systems.
Condensing oil furnace
Heat is carried away not only in the high temperature of the flue
gases but also in the water vapour they contain. The water vapour
that is produced when fuel is burned holds a substantial amount
of latent heat. For natural gas, this latent heat is approximately
11 percent of the energy in the fuel. Oil, on the other hand,
produces only half the water vapour of natural gas; thus, oil has
much less energy in the form of latent heat.
A condensing furnace uses a second heat exchanger that is made of
stainless steel to extract more heat from the combustion gases before
they leave the furnace. This practice reduces the exit temperature to
between 40° and 50°C (104° and 122°F). The result is that water
vapour from the flue gas condenses inside the heat exchanger and
releases its latent heat to the house air that is circulating through
the furnace. At this time, the combustion gases are so cool that they
require only a narrow plastic vent pipe that goes out the side wall
of the house instead of up the chimney. The condensate runs to a
drain outlet.
The potential for efficiency improvements by condensing the flue
gas is much lower for oil than for natural gas because:
• thedewpointforoilislowerthanfornaturalgasbecause
oil contains only half as much hydrogen as natural gas.
Consequently, the furnace has to work harder to condense less;
• thecondensatefromoiliscorrosivebecauseofitshighersulphur
level, so that a condensing heat exchanger for oil must be more
corrosion-resistant than one for natural gas;
• oilcombustionalsoproducessomesoot,whichcanconcentrate
the acidic condensate as “acid smut” on the surface of the
heat exchanger.
A new condensing oil furnace is available that addresses many
of these issues. It uses a very high quality heat exchanger and a
high-static burner. Plastic CPVC or ABS pipe can be used to vent
the combustion products out the side wall of a house without a
chimney because the flue gas temperature is very low (≈40°C). It
is too soon to know if all the concerns with oil-fired condensing
systems have been resolved by this furnace, but the results to date
look promising.
In-house condensation problems
More efficient heating systems, combined with better draft
proofing and insulation, can result in less air infiltration which, in
turn, may lead to excess moisture in the house, particularly on
cold winter days.
Heavy condensation on the inside of windows and dampness or
mould growth on walls or ceilings are indications of too much
moisture. If these are not corrected, serious structural damage
will eventually occur; luckily, indoor condensation problems can
be solved.
Because most of the indoor humidity is caused by regular
household activities (such as showering and cooking), your first
step should be to reduce the amount of moisture from these
sources. You can do this, for example, by ensuring that your
clothes dryer vents to the outside, using lids on pots when
cooking, and keeping showers short.
The National Building Code of Canada requires that all new
homes have some form of ventilation, although provincial or
territorial regulations may not. However, you should consider
installing exhaust fans in the bathroom and kitchen that vent
directly to the outside.
You should also check the humidifier setting on your furnace,
if it is equipped with one. It may not be necessary to have a
humidifier in a more airtight house. You should also talk to
a contractor about installing an HRV that will increase the
ventilation in your house and decrease humidity without
wasting energy.
In-chimney condensation problems
In-chimney condensation is another possible problem. The
lower flue temperature achieved by the improved efficiency of
today’s heating equipment has created the possibility of flue
gas condensation damaging the inside a masonry chimney,
particularly one located on the outside wall where it is chilled by
exposure to the outside air.
Look for a white, powdery efflorescence on the outside of the
chimney, spalling or flaking of the bricks, crumbling mortar
joints, wet patches on inside walls behind the chimney, pieces
of tile at the bottom of the chimney, and water running out of
the cleanout door or around the bottom of the chimney behind
the furnace.
The most common cause of these problems is condensation
inside a cold chimney. Water vapour is produced when oil
or natural gas is burned, but humid house air drawn into the
chimney also contributes to the problem.
Another cause of condensation is chimneys being larger than
necessary. Furnaces that are more efficient need chimneys that
are smaller than the 200 mm × 200 mm (8 in. × 8 in.) flue tile
that had been standard for many years. The combustion gases,
already cooled by the improved heat exchanger in the furnace,
rise slowly in the cold, oversized flue, where they are sometimes
cooled to the dew point of the water vapour they contain. The
resulting condensation can then leak into the bricks and cause
structural or water damage.
Simple remedies are available if the damage is found in time.
The use of a double-walled stainless steel flue pipe from the
furnace to the chimney or a stainless steel chimney liner, or
both, can usually stop this damage.
Other solutions to these problems are described in Chapter 6.
Comparing annual
heating costs
The combination of annual heating load, energy source and
equipment efficiency determines the annual cost of heating.
For help determining your annual heating costs, NRCan
has developed an online tool called the “Home Heating
Cost Calculator,” which is at oee.nrcan.gc.ca/equipment/
Heating costs when upgrading an existing
oil heating system
If you are currently heating with oil and are considering converting
to a more efficient oil heating system, you may be interested in
determining the savings you could expect. Table 1 (page 43) and
the following formula can provide reasonably accurate figures.
You need to know your annual fuel cost and the type of heating
technology you are using.
Annual cost savings =
A = seasonal efficiency of the proposed system
B = seasonal efficiency of the existing system
C = current annual fuel cost
Example: How much would you save by changing from an
old oil furnace to a new oil furnace with a high-static burner at
85 percent efficiency, if your current annual fuel cost is $1,205?
The seasonal efficiency of the new furnace with a high-static
burner is taken to be 85 percent, and the present oil furnace
efficiency is 60 percent. Hence, A = 85 percent, B = 60 percent,
(these numbers represent an average of the efficiency ranges
given in Table 1) and C = $1,205.
Annual cost savings =
85 − 60
× 1205 = $354
Thus, you would save $354 per year with this new oil furnace.
Typical heating system efficiencies and energy savings
(AFUE) (%)
(% of Base*)
Cast-iron head burner (old furnace)
Flame-retention head replacement
High-static replacement burner
New standard model
Mid-efficiency furnace
Integrated space/tap water**
0–31 space
0–41 water
Vent damper with non-continuous
pilot light
High-efficiency condensing furnace
Integrated space/tap water**
0–37 space
0–47 water
Electric baseboards
Electric furnace or boiler
Air-source heat pump
1.7 COP***
Earth-energy system
(ground-source heat pump)
2.6 COP***
Vent damper with non-continuous
pilot light
Central furnace
Conventional stove
(properly located)
“High-tech” stove****
(properly located)
Advanced combustion fireplace
Pellet stove
* “Base” represents the energy consumed by a standard furnace.
** Precise data will be available after the new standard is developed.
*** COP = Coefficient of performance, a measure of the heat delivered by a heat pump
over the heating season per unit of electricity consumed.
**** CSA B415 or EPA Phase II tested.
Heating costs with various energy sources
You may be interested in calculating the cost of heating with oil
and also comparing this amount to the costs of heating with other
energy sources such as electricity, natural gas, propane or wood. To
do this, you can use the following steps. You need to find out the
cost of the energy sources you wish to compare and the types of
heating technologies that you might want to use.
Step 1: Determine the cost of energy
sources in your area
Call your local oil, gas and electricity suppliers to find out the
cost of energy sources in your area. This should be the total cost
delivered to your home, and it should include any basic cost that
some suppliers might charge, together with necessary rentals, such
as a propane tank.
Be sure to get the prices for the energy sources in the same units as
shown in Table 2. Write the costs in the spaces provided. If your local
natural gas price is given in gigajoules, you can convert it to cubic
metres (m3) by multiplying the price per GJ by 0.0375. For example,
$5.17/GJ × 0.0375 = $0.19/m3. Fuel oil is usually sold in litres.
Energy content and local cost of various energy sources
Energy content
Local price
38.2 MJ/L
140 000 Btu/gal. (U.S.)
$0. _________ /L
3.6 MJ/kWh
3 413 Btu/kWh
$0. _________ /kWh
Natural gas
37.5 MJ/m3
1 007 Btu/cu. ft.
$0. _________ /m3
25.3 MJ/L
92 700 Btu/gal. (U.S.)
$0. _________ /L
30 600 MJ/cord
28 000 000 Btu/cord
$_________ /cord
18 700 MJ/cord
17 000 000 Btu/cord
$_________ /cord
19 800 MJ/
20 000 000 Btu/ton
$_________ /tonne
Conversion 1000 MJ = 1 GJ
*The figures provided for wood are for a “full” cord, measuring 1.2 m × 1.2 m × 2.4 m
(4 ft. × 4 ft. × 8 ft.). In practice, wood is usually sold as a face cord, which is typically one
third of a full cord.
Step 2: Select the type of heating
Choose the type of equipment you want to compare from the list
of appliance types in Table 1 on page 43. Note the efficiency figures
in the column titled “Seasonal efficiency.” By using these figures,
you can calculate the savings you can achieve by upgrading an older
system to a newer, more energy-efficient one or by choosing higher
efficiency appliances with alternative energy sources.
Step 3: Determine your home’s annual
heating load
If you know your heating bill and the unit cost of your energy
source, you can determine your annual heating load in gigajoules
using the following equation.
Annual heating heating bill seasonal efficiency energy
= 100 000 × energy cost/unit × content
For example, you have an oil bill of $ 1,700, an oil cost of
$0.529/L and a conventional oil furnace and burner (seasonal
efficiency of 60 percent from Table 1).
Annual heating
100 000 ×
× 38.2 = 77 GJ
If your bill also includes tap water heating from the same energy
source, you can still calculate your annual heating load, but it
will require a little more care and calculation to separate the
heating portion.
If you can’t get your heating bill, you can estimate your annual
heating load in gigajoules from Table 3 (page 47) by selecting the
house type and location that is closest to your own.
Step 4: Use the formula
The annual heating cost is calculated as follows.
Energy cost/unit annual heating load
× 100 000 = heating cost
energy content
seasonal efficiency
• • • The result gives you an approximate heating cost for your
house. If you know your actual annual heating costs, as well
as the type of heating system you have, you can modify
the heating load originally taken from Table 3 to suit your
specific house.
Sample calculation: You have a new semi-detached home in
Fort McMurray and you want to know what the annual heating
cost would be with a mid-efficiency oil furnace at 83 percent
efficiency. Using the above formula, we can define the cost of
oil as $0.529/L, the house heating load as 80 (Table 3) and the
energy content as 38.2 (Table 2).
Annual cost of oil heating:
$0.52930 80
× 100 000 = $1330
If you want to compare this heating cost with those of other types
of heating systems or energy sources, replace the numbers in the
formula with the appropriate ones for your comparison using
Tables 1 and 2 (pages 43 and 44).
Typical annual heating loads for various housing types
in Canadian cities
Prince George
Fort McMurray/Prince Albert
Thunder Bay
Québec City
Saint John
St. John’s
Note: “New” means houses built in 2004 or later, and “old” means houses built
before 2004. Due to construction practices, “weatherizing” and re-insulating
can be different from house to house so that these figures are meant to be used
only as general guidelines. They should not substituted for an accurate heating
requirement determination, as discussed in Chapter 5.
Old detached – approximately 186 m2 (2000 sq. ft.)
New detached – approximately 186 m2 (2000 sq. ft.)
New semi-detached – approximately 139 m2 (1500 sq. ft.)
Townhouse – inside unit, approximately 93 m2 (1000 sq. ft.)
Buying, installing or
upgrading a system
You cannot shop for a furnace in the same way that you shop for
a camera or a pair of shoes. There are few “furnace stores” where
the different makes and models may be examined, compared and
priced. To get first-hand information on the different makes and
models available, you will have to contact several heating firms.
Ask them for the manufacturers’ illustrated sales literature for the
furnaces they sell and install. You should also contact your oil
supplier or a contractor for assistance and information.
If you have decided on a particular type of furnace, read the
literature carefully to find out if it describes the features you are
looking for – such as a high-static flame-retention head burner
and a delayed-action solenoid valve. Look for its efficiency rating.
You want the seasonal (AFUE) rating, not just the steady-state
efficiency. Make sure you distinguish between the two types of
ratings. Compare it with Table 1 on page 43.
As previously mentioned, even the best oil furnaces do not run at
their maximum efficiency if they are oversized, and they can make
your home uncomfortable. Do not automatically buy a new furnace
that is the same size as your present one; it may be as much as three
times too large.
A heating contractor cannot determine the size of furnace you
need just by walking through your house. The contractor has to
calculate the heating requirements of your house using one of the
following methods:
• usingthefuelconsumptionofyourpresentfurnaceovera
known winter period together with
– the nozzle size
– the steady-state efficiency
– the degree-days between oil deliveries
– the amount of oil consumed over that period
– the design temperature for your region
• makingathoroughmeasurementandexaminationofyour
house to determine
– insulation levels
– degree of air tightness of the house envelope
If the contractor does not use any of these factors, his or her
calculation of the correct size for your new furnace will be just
a guess.
To make sure proper furnace sizing is determined, the quotation
and contract should include a statement such as this one: “The
furnace size will be determined by a heat loss calculation using
the formulas published by: the Canadian Oil Heat Association;
the Heating, Refrigerating and Air Conditioning Institute of
Canada; the Canadian Standards Association; Natural Resources
Canada; or other recognized organization. A copy of these
calculations will be given to the homeowner.”
It is important to hire a contractor who will install your equipment
properly to ensure that it will operate efficiently. Check with your
local fuel dealer or provincial/territorial heating fuel regulatory
office to find out how to contact a qualified, registered or licensed
contractor. If your neighbours have had similar work done recently,
ask them how satisfied they were with their contractors. If you are
buying a relatively new type of furnace design, try to get the names
of other homeowners who have had such equipment installed,
and find out about the appliance’s performance and the work of
the installer.
Before you decide what to buy, obtain firm, written bids from
several companies on the cost of
• upgradingyourexistingequipment
• buyingandinstallingacompletelynewunit
• anyotherfittingsandadjustmentsrequired,includingchanges
to any ductwork or piping
• afinalbalancingoftheheatsupplytothehouse
With these figures and a reasonable estimate of the probable
annual fuel savings determined from Table 1 on page 43, you can
determine how long it will take to recover the cost. The payback
period is not the only factor to consider but it is certainly one of
the most important.
Remember that a building permit may be required for this type
of work, and the contract should state whether the installer or the
homeowner is responsible for obtaining it.
Checklist for installing an oil heating system
Get several estimates on the work to be done. When you are
comparing these estimates, cost will be an important factor,
but there are other elements to consider. Some contractors are
better at explaining what has to be done. Some may use higherquality components, and others may schedule the work at
your convenience.
Estimates should include the following items.
• Thetotalcostofall necessary work.
• Anitemizedlistofall material and labour costs included in
the bid:
– alteration or improvement of existing heat distribution ducts;
– installation of the water heater and vent (where applicable);
• Astatementdescribinghowmuchofanyexistingequipment
will be used in the new system.
• Aroughdiagramshowingthelayoutofductworkorwaterpipes
and the location of supply piping and heating equipment.
• Astatementthatclearlydefineswhoisresponsiblefor
– all permits and the payment of related fees,
– on-site inspections, as required,
– the scheduling of all other required work,
– all related costs, such as subcontracts with trades people.
• Aclearestimateofwhentheworkwillbecompleted.
• Awarrantyformaterialsandlabour.
• Ascheduleandmethodofpayment.
Ensure that the technician is qualified to do the work. Ask
contractors for the names of homeowners for whom they have
done similar work. The Better Business Bureau will know if the
contractor is a member and whether any recent complaints have
been filed against him or her. Your local Chamber of Commerce or
Board of Trade may also be able to help.
Some dealers will also rent heating equipment or offer leaseto-purchase plans. You may want to use these plans rather than
purchase the equipment outright.
Do not hesitate to ask the contractor for a clear explanation of any
aspect of the work before, during or after the installation of your
heating system.
Billing for oil is handled in different ways, with two of the most
common methods being equal billing and standard billing.
Equal billing: Your oil bill is paid in equal instalments, based on
an estimate of your annual consumption. Periodic adjustments
are made to balance your instalment amount against your actual
annual consumption.
Standard billing: The bills are paid for the amount of oil consumed
during that period.
Carbon monoxide detectors
Because modern houses are more airtight and have more powerful
air-exhausting systems, there is a greater chance that combustion
products – which contain deadly CO gas – will linger inside
your house and build to potentially dangerous levels. A certified
CO detector located close to fuel-fired appliances (such as
furnaces, fireplaces, space heaters, wood stoves and gas or propane
refrigerators) will signal the presence of CO, which must be
corrected immediately.
Symptoms of low-level CO poisoning are similar to those of the
flu – headaches, lethargy and nausea.
If you have a conventional wood-burning fireplace, which can
leak CO, and you plan to use it often, it would be wise to install
a CO detector.
Contractor maintenance
The best way to keep heating equipment operating at peak
efficiency is with a regular program of expert cleaning, servicing and
burner tune up. This must be done at least once a year, preferably
well before the heating season arrives, and it must be done properly.
Furnace manufacturers and the instructors who train service people
agree that a proper cleaning and tune up requires at least 1.5 h,
but often it takes longer. To clean and thoroughly service a
boiler may take 2.5 h.
Here are the tasks that a service person should perform at every
annual cleaning and tune up.
• Inspecttheinsideandoutsideofthechimney.
• Cleanthefurnacefluepipe,barometricdamperand
chimney base.
• Checktheconditionofthefurnaceheatexchanger.
• Usebrushesandavacuumcleanertoremovesootbuildupfrom
the heat exchanger cavities inside the furnace. These are difficult
to reach in many furnaces and it takes patience and perseverance
to do a good job.
• Cleanthefurnacefanthoroughly(thisstepappliesonlyto
warm-air systems). Dirt buildup on the curved blades can
reduce the amount of air that is moved, which decreases furnace
efficiency. On a belt-driven fan, the motor should be oiled where
possible and the belt tension checked. Every two or three years,
the fan, should be removed from the furnace for a thorough
examination and cleaning.
• Cleanorreplacetheairfilter(forced-airsystemsonly).
• Opentheburnerandcleanandlubricatethemotorand
blower fan, if required. If the nozzle is dirty, it should be
replaced, not cleaned.
• Checktheoilpressureintheburnerandexamineallfittings
for leaks.
• Cleantheoilfilterbowlandreplacethecartridge,ifnecessary.
• Checktheperformanceofthesafetyfeatures,suchasthehigh
limit control and the sensor for the cad cell flame.
The next equally important job is adjusting the furnace for
maximum efficiency. This adjustment requires four measurements
made through a pencil-sized hole in the flue pipe, close to the
furnace. Do not worry about flue gases escaping through this hole.
In a properly adjusted furnace, this will not happen.
After the furnace has been running for approximately 15 min to a
steady flue temperature, a sample of the flue gases is tested for its
smoke content, and the draft pressure is checked. Then the final
two measurements are taken to determine the steady-state efficiency
of the furnace, which are the temperature and the carbon dioxide or
oxygen content of the flue gases leaving the furnace.
All four measurements are essential to the proper adjustment of
an oil furnace for optimum combustion performance.
You can tell whether your furnace has ever had such attention by
looking for a pencil-sized hole in the flue pipe. If there is no hole,
the smoke level and draft pressure have never been tested and the
steady-state efficiency has never been checked. If this is the case,
talk to your fuel oil supplier or service person about it.
Service plans
You may find it helpful to buy an annual furnace service plan.
This plan provides an annual inspection, cleaning and tune up,
and 24-hour emergency repairs. Some plans include parts and
labour; others cover labour only, which means you must pay for all
parts required. Some firms offer additional insurance for complete
furnace replacement, if this is ever necessary. An inspection is
required before the service contract is signed.
Owner maintenance
You can do several maintenance tasks yourself to keep your
system working well. But even if you do these properly and
regularly, you should still have your system serviced annually by a
heating contractor.
Routine chimney care
Most oil-fired furnaces and boilers require one of the following
types of chimney:
• TypeAchimney(adouble-walled,insulated,prefabricatedmetal
chimney with a stainless steel lining);
• masonrychimneylinedwithaclayfluetile;
• masonrychimneylinedwithacertifiedstainlesssteelliner.
Note that side wall-venting models have different venting
The flue liner should be sized in accordance with the CSA standard
CAN/CSA-B139-09, Installation Code for Oil-Burning Equipment.
Although an oil furnace chimney rarely, if ever, needs to be cleaned,
it should be checked occasionally for any sign of deterioration.
You can check this by inserting a mirror in the cleanout opening
at the bottom of the chimney on a bright day. Look for a broken
or flaking flue liner or interior chimney damage, as well as for
water running out of the cleanout door or around the bottom of
the chimney behind the furnace. Then examine the outside of the
chimney. Look for a white, powdery efflorescence on the outside
of the chimney, spalling or flaking of the bricks, crumbling mortar
joints, and wet patches on inside walls behind the chimney.
Certain types of higher-efficiency systems have special needs that
may require your attention. Check your owner’s manual or discuss
this with your installer or service person.
Dealing with condensation in the chimney
The low temperature of the chimney itself is the major cause of
condensation inside it. This problem can be overcome by installing
an insulated metal liner such as a Type L, double-walled, stainless
steel liner or a single-walled stainless steel liner surrounded by
insulation. Check with your provincial/territorial fuel safety
division to find out which method it approves.
Remember, using a sealed, double-walled stainless steel flue
pipe from the furnace to the chimney is a good way to keep
flue gases at a temperature high enough to help prevent
condensation in the chimney.
A furnace physical
There is a simple way to monitor the condition of your furnace or
boiler and how efficiently it is using fuel. As we have seen, the heat
that is not distributed through your house goes up the chimney, so
measuring the temperature of the flue gases leaving the furnace will
give a fairly accurate indication of its performance.
The maximum temperature allowed for the flue gases leaving the
furnace has been 400°C (750°F) for a conventional oil-fired furnace
manufactured during the last 30 years. The flue gas temperature is
normally between 175°C (350°F) and 280°C (540°F). To measure
this, you need a specific probe-type metal thermometer (Figure
11) that looks like a meat thermometer but reads much higher
temperatures – to at least 400°C (750°F). You can get one from a
heating supply company or order one through a hardware store.
Flue pipe thermometer
If the flue pipe does not have a hole, make one in the side of it,
with a large nail or an electric drill, approximately 40 cm (15 in.)
from the furnace exit (but not right after a large bend). Insert the
flue pipe thermometer probe. The end should be near the centre of
the pipe.
You can leave the thermometer in the hole permanently, if you
want. If you do this, remember before you take a new reading to
remove the thermometer and clean the end of the probe to remove
any soot that may have built up. Turn the thermostat up to the
maximum heat and let the furnace run for at least 15 min before
taking a reading on the thermometer. Remember to turn the
thermostat back down after you have finished.
Check the temperature before and after the furnace is serviced to
see if it has changed. Note any steady increase through the heating
season. A rise of 25°C (77°F) represents a drop of approximately
3 percent in furnace efficiency and a corresponding increase in fuel
consumption. In a forced-air heating system, this may mean only
that the air filter needs to be cleaned or replaced. If replacing the
air filter does not reduce the flue temperature to near where it was
before, call your service company.
Owner maintenance of forced-air
heating systems
Cleaning or changing the air filter
IMPORTANT! Turn off the power to the furnace before opening
the furnace access panel to check the filter or fan.
Few homeowners give the air filter in a furnace the attention it
needs. It should be cleaned or replaced at least twice during the
heating season. You can get permanent filters made of aluminum
or plastic mesh that can be washed by hand, but the mesh is not as
fine as glass fibre filters and does not trap as much dirt.
If you add an electrostatic air filter to your furnace, you do not
need a standard filter as well. Remember that these electrostatic
filters also need to be cleaned regularly. Check the owner’s manual
for instructions.
Fan care
The only maintenance that a homeowner can perform on a furnace
fan is superficial vacuuming.
Distribution system care or maintenance
Remove obstructions from ducts, warm air registers and cold air
returns so that air can move freely around the system. Use a waterbased duct mastic to seal any cracks in the duct joints, as described
on page 24. Also consider insulating all the warm air ducts that you
can access easily.
Owner maintenance of a hydronic system
A homeowner can do the following maintenance work for a hot
water heating system.
• Insulatethehotwaterpipes.
• Onceortwiceayear,bleedairbubblesoutoftheradiatorsso
that they can fill with water.
• Vacuumtheradiators.
• Checkthatthelevelofwaterintheexpansiontankisbelow
flood level.
• Oilthecirculatingpump(accordingtothemanufacturer’s
• Allowairtoflowfreelyaroundradiators.Ensurethatradiators
are not covered by curtains or by ventilated wood panelling, and
try to ensure that they are not directly behind furniture so that
the heat generated can get into the rest of the room.
Domestic water heaters
Some Canadian homes that are heated with oil also use oil for
their domestic hot water supply. Domestic water heaters are
the second-largest individual users of energy in most Canadian
houses after the space heating system. Depending upon the house
type and the number and lifestyles of the inhabitants, hot water
consumption may account for more than 20 percent of total annual
energy consumption.
Free-standing oil-fired water heaters (see Figure 12 on page 60) now
use burners that have flame retention heads and other modifications
that improve efficiency. The water heaters can be connected to
an existing chimney or, in some cases, can be side-wall vented, if
approved for it.
Most direct heat loss from water heaters is made up of losses: by
air and heat flow up the flue, both when the burner is firing and
when it is not; by heat conducted through the tank walls and base;
and by hot water convection losses through the hot and cold water
feed pipes.
This chapter examines the options for improving the efficiency of
the domestic hot water system by selecting and properly installing
more efficient equipment.
Reducing energy losses
There are two basic types of oil-fired tap water heating systems:
• aconventionalwaterheaterthatheatsthewaterdirectlyin
a tank;
• asystemthatheatsthewaterinconjunctionwithanother
energy use, usually space heating.
For the latter, it can be in the form of a “tankless coil” inside the
boiler or inside a storage tank connected to the boiler through a
water-to-water heat exchanger.
The operating efficiency of a domestic hot water system can
be improved by designing the system carefully and selecting
equipment that generates hot water more efficiently and reduces
stack and standby losses. Modifying an existing system, including
piping modifications, can also reduce some of the standby losses.
Comparable to the AFUE of furnaces, the energy factor measures
the seasonal performance of water heaters – the higher the number,
the better the efficiency.
Oil-fired hot water heater
Hot water supply
Reducing standby losses
The term “standby loss” refers to heat lost from the water in a
domestic water heater and its distribution system to the surrounding
air. The amount of loss is a function of the temperature difference
between the water and the surrounding air, the surface area of the
tank, and the amount of insulation encasing the tank.
Before carrying out any of the following steps, check with
your local installer or oil dealer to ensure that you will not
compromise the safety or operation of the appliance.
Consider the following options to reduce standby losses.
• Installheattrapsabovethewaterheater.Aheattrapisapiping
arrangement that prevents hot water from circulating by
convection within the pipes and carrying heat from the tank to
where the heat will be lost from the pipes to the surroundings.
• Insulatehotwaterpipestoreducetheheatlossfromthepipes
themselves. Pipe insulation is available in a variety of materials
and thicknesses, and are easily applied to most hot water pipes.
Install insulation with an RSI (insulating value) of at least 0.35
(R-2) over as much of the pipe as you can access easily and
within 2 m of the water heater.
It is extremely important not to insulate over any controls or
obstruct the vent connections or combustion air openings. The
insulation should not come in contact with the vent connector.
Integrated space and water heating systems
Improvements to the building envelopes of homes have reduced
the space heating load to the point that, in highly energy-efficient
homes, it is sometimes difficult to justify the expense of a highefficiency furnace solely to satisfy the heating load.
To take advantage of the efficiency potential of the new
technologies, it may make sense to combine space heating with
other functions, particularly water heating. Domestic hot water
loads have increased relative to heating loads over time, making
it a good idea to put more effort into improving the efficiency of
the hot water generator. Therefore, it would be advantageous to
combine efficient space and water heating systems.
Schematic of an efficient oil-fired integrated
space-water heating system
House radiators
Cold water return
Hot water
Oil-fired boiler
Heat storage – tap water heater
Combining the functions of space and water heating in one unit
can reduce the capital cost of the equipment and potentially
increase efficiencies of operation. A schematic of such a system is
shown in Figure 13.
The efficient integrated oil system couples a mid-efficiency or
condensing, low-thermal mass boiler fired with a high-static burner
to a well-insulated water storage tank by using an efficient waterto-water heat exchanger. When the house thermostat calls for heat,
the boiler supplies heat to the house, either directly into a hydronic
system or into a forced-air distribution system through a fan coil.
When the house thermostat demand is satisfied, the boiler, instead
of shutting off, continues to run, but releases the heat across the
heat exchanger into the tap water storage tank.
There are also oil-fired boilers on the market that provide a
continuous supply of domestic hot water by circulating cold water
through a finned copper coil that is immersed directly in the boiler
water. These systems are tankless coil boilers. The boiler must be
kept hot even during the summer to give an adequate supply of
tap water.
Most tankless coil boiler systems are very inefficient over the
entire year.
Combined space-water systems that are based on an oil-fired tank
water heater and fan coil tend to be quite inefficient.
Another arrangement uses a conventional oil-fired hot water heater
as the basic energy generator and supplies the heated water to the
house through a fan coil. Although this system has the advantage
of a lower initial capital cost, its efficiency may be worse than the
other systems described above.
Integrated systems are being developed which offer promise for
further improvement.
If you are considering upgrading or replacing your heating system,
you may want to consider installing an integrated space and water
heating furnace or boiler. The energy consumption for space and
water heating may be higher if these services are provided by
separate units rather than by a single, integrated unit. In other
words, integrated units may offer energy savings while providing
the same space heat and hot water.
More information
Free publications from the OEE
The OEE of Natural Resources Canada offers many publications
that will help you understand home heating systems and home
energy use. These publications explain what you can do to reduce
your energy use and maintenance costs while increasing your
comfort and helping to protect the environment.
To obtain additional copies of this or other free publications on
energy efficiency, contact:
Energy Publications
Office of Energy Efficiency
Natural Resources Canada
c/o St. Joseph Communications
Order Processing Unit
1165 Kenaston Street
P.O. Box 9809, Stn T
Ottawa ON K1G 6S1
Tel.: 1-800-387-2000 (toll-free)
Fax: 613-740-3114
TTY: 613-996-4397
Publications can also be ordered or viewed on-line at the OEE’s
Energy Publications Virtual Library at oee.nrcan.gc.ca/infosource.
Natural Resources Canada’s Office of Energy Efficiency
Leading Canadians to Energy Efficiency at Home, at Work and on the Road
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