Heating System
APPENDIX 2:
Heating System
The heating system in any building is likely to be the biggest
user of energy, and the system in which the greatest savings
can be made. There are many different ways that a heating
system can work. Traditional gas boilers heat water which
heats the air in the building.
Air conditioning systems heat the air directly and then
distribute it around the building. Many other fuels can be
used other than gas, and air conditioning can come in many
different shapes and sizes.
Despite their differences, all heating systems have the same basic principles, and these are where we
can locate possible energy savings.
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2.
3.
4.
Energy is fed into the system
Heat is generated
Heat is transferred to where it will be used
Heat is lost
Where the energy is put into the system, this may be from a renewable energy source, or a very high
carbon energy source. Similarly, it may be a cheap fuel or an expensive one. When the heat is generated,
this process will never be 100% efficient, so there may be improvements that can be made, often by good
maintenance of the boiler or other heating unit.
While the heat is transferred, there can be losses in pipe work, or in the unit used to transfer the heat to
the room. Pipes should be well insulated to keep as much heat in as possible, and radiators or fan coils
should be well maintained, efficient models.
Finally, once the building has been heated, this heat will escape. To save energy, ensure that the heat
takes as long as possible to escape the building. Do this by improving insulation and draught proofing, and
by keeping doors and windows closed while the building is being heated.
More details on how to maintain an efficient heating system are given below.
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At the end of the life of an air conditioning system, consider installing either a high efficiency boiler or heat-pump and remote condenser, selected from the ECA list. The ECA list provides 100%
first year Enhanced Capital Allowances (ECA). This allows the full cost of an investment in
designated energy-saving plant and machinery to be written off against the taxable profits of the period in which the investment is made. See www.eca.gov.uk/etl/
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Consider installing a high efficiency boiler or high COP heat pump selected from the ECA list
to qualify for a 28% capital allowance. The heat pump could be part powered by any photovoltaics installed.
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It is recommended that any heating system be investigated in order to identify areas for
improvement, such as independent control of the different building parts. It is likely that not every room needs to be the same temperature all of the time, or run on the same schedule, so zoning is an important tool.
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Consider commissioning an in-depth review of your Building Energy Management System to identify areas of savings and investment costs.
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Consider installing destratification fans to provide mixing of the air within any rooms with high
ceilings. This avoids heat collecting in the rafters and moves the heat to floor level where it will be used.
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Consider installing sensors to windows to ensure that the heating is switched off should any
windows be opened to reduce heat loss to the exterior environment.
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The Efergy energy monitor1 also helped to identify good practice housekeeping measures such as the optimisation of hot water night storage heating at one club. At another club it helped to demon
strate an annual cost saving of £839 achieved by installing LED lighting.
MAINTENANCE
Regular maintenance is essential for maximum efficiency. Ensuring the boilers are regularly serviced by
qualified heating personnel is vital.
Any leaks in the pipe work require urgent attention. Heat exchangers and fans should be checked and air
intake filters cleaned or replaced regularly. Air distribution should be balanced so that all rooms are at an
appropriate temperature.
Poorly maintained or disconnected thermostats and central control systems are one of the most common
sources of poor temperature regulation and high energy use in buildings with central heating systems.
Ensure your maintenance contractor checks and reports on the heating control system and seeks
specialised advice where necessary.
THERMOSTATIC RADIATOR VALVES
Thermostatic radiator valves (TRV) are very useful to improve the overall
energy efficiency of any building. Heating and energy use account for a
large portion of the UK’s annual CO2 output. By optimising our building’s
energy efficiency you can reduce not only our heating bills, but also the
amount of CO2 emissions released.
TRV can cut heating energy costs up to 20% while improving comfort.
They automatically control the flow through your radiator to heat
each room based upon their “need” (in terms of the temperature
setting for that radiator) rather than a manual or default flow.
1
See appendix ‘3 Cooling System’ for more information
Whilst a standard “flow to all radiators” manual system does provide heat, it also wastes heat in overheating areas which are already warm enough. It also cannot compensate for variable aspects such as the sun
shining through a window, people being in the room, heat generated by appliances in the room etc. This
results in half the building being too warm, and parts of it not being warm enough.
Thermostatic valves need no external power; they maintain the room temperature by controlling the
volume of hot water or steam flow. The valve body are usually made of noncorrosive nickel-plated bronze/
brass.
TRVs cost normally between £5 and £20 depending on make, style, aesthetics, flow direction (one way or
dual) and where you buy.
WHAT ARE THE ADVANTAGES OF A THERMOSTATIC VALVE?
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•
•
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Wide temperature control range.
Automatic “freeze protection” and shut-off-protection.
The specially designed valve head with its air circulation feature and long isolation stem prevents interference by flow medium temperature.
The head is securely fastened to the valve body through its unique holding nut design which
prevents any loosing problems.
Wide range of thermostatic heads suitable for all applications
Lockshield ring or protection cap prevents theft of or damage to the
thermostatic head.
TIMERS
Running the central heating/hot water system continuously is
prohibitively expensive for most users. One certain way of holding down
a building’s heating bills is to switch the system off as often as possible.
Of course, this can be done only when room and water heating system
are not needed.
Time controls on most heating/hot water systems are among the first
essentials for improving home comfort and reducing running costs.
All pumps, fans, boilers and furnaces should be switched by an automatic
timer. These can often be set such that they will not operate over holidays
and weekends. A 7-day timer can be programmed to eliminate weekend
operation, and each day can be given a different schedule at the beginning
of the week.
Analogue timer
Ensure as well that there is a different program for each season, since
requirements for space heating will not be the same in summer, winter,
autumn or spring.
THERMOSTATS
Digital timer
Controlling room temperatures is an important way of saving energy. A 1°C reduction in room temperatures
can lower heating costs by up to 10%. The calibration of room thermostats can be checked by reading room
temperatures with a thermometer placed next to the thermostat. Control panels can be enclosed or protected so that only authorized personnel can change the settings.
The most important rule with thermostats is to ensure that they are in the right place. If a thermostat is
placed next to a source of heat or a draughty place, the thermostat will not work properly. The extra heat
generated by a computer, a kettle, or even a light bulb that is too close to the thermostat will make the
thermostat think that the room is hotter than it is, and will turn the heating off when it should still be on.
Similarly, if the thermostat is in a cool place, in a draught or near a chilled object, it will think that the room
is cooler than it is and turn the heating up.
Use thermostat controls to prevent over or under heating. Over heating can be a problem during spells of
mild weather. Under heating can also be an expensive problem if portable electric heaters are used to top
up the main heating system. Set thermostats at the lowest comfortable temperature in winter (18°C–20°C).
Temperatures in changing rooms need to be set slightly higher at about 21°C. Corridors and stairwells can
also be at a lower temperature provided this does not result in cold draughts into the rooms.
MOTORISED VALVES
Motorised valves in ‘wet’ central heating systems control the flow of
heated water from the boiler to primary circuits, i.e. to radiators and
HWS cylinder coils.
Operated by small (5W or 6W) synchronous electric motors and activated
by time controls and thermostats, they help maintain desired comfort
levels and save fuel by ensuring heated water goes only to where it is
needed – and when.
Motorised valves are the last step to complete the operating sequence
for “wet” central heating systems, where each user-set, timed switching
Motorised valve
programme helps maintain desired comfort levels and prevents excessive
fuel consumption by inhibiting unnecessary boiler firing. This is one of
the best ways to keep your building with the maximum comfort and with a high efficiency.
Please see below the operating sequence for central heating systems, with the different parts and their
following explanations:
TIME
CONTROL
Sends time ON/OFF
signals to thermostat
THERMOSTATS
(ROOM OR CYLINDER)
If heat demand exists,
switches close and pass
signals to valve(s)
RELEVANT
MOTORISED
VALVES
BOILER AND
PUMP
Motor opens valve(s),
activates auxiliary
switch to boiler/pump
Boiler can only fire
when a demand for
heat exists
INSTALLING RADIATOR REFLECTOR PANELS
Radiator reflector panels (insulated sheet of aluminium foil) are an attractive low-cost option. Fixed
behind your radiators, they reflect heat from the radiator back into the room, instead of letting the heat
out through an external wall. This is cost-effective for all types of wall construction with the largest returns
expected with solid, un-insulated walls through which the rate of heat loss is greatest.
The price for these panels is around £3.50 per sheet, and is even cheaper if bought in bulk, so this solution
is highly recommended given its cost to savings ratio.
INSULATING PIPES
Insulating hot water pipes means encasing the pipes that conduct hot water from the hot water heater to
where the water is demanded. This includes hot water for space heating. Insulating these pipes saves
water, energy, and money compared to leaving pipes un-insulated.
BENEFITS
It is advisable to have proper pipe insulation installed, especially in the cold season. Pipes without insulation are subject to increased heat loss, which can make heating your building and using hot water more
expensive, simply because more heat has to be generated.
Pipe insulation is useful, cheap and easy to install, therefore you should make sure that any pipes that
require insulation are properly taken care of.
Since pipe work can operate at temperatures very different to the ambient temperature, and the rate of
heat flow from a pipe is related to the difference in temperature between the pipe and the surrounding
ambient air, heat flow from pipe work can be considerable. In most situations, this heat flow is undesirable.
For example, in a radiator heating system, the rooms will gain heat more efficiently from the radiators than
the pipes, partly due to the location of the radiators, but also due to their design. The application of
thermal pipe insulation introduces thermal resistance and reduces the heat loss rate.
Make sure that it is not just the straight sections of pipe that you insulate. It is just as important to insulate
the bends and joints in the pipes. There can be as much heat lost in one joint as in 1m of straight pipe.
REASONS FOR PIPE INSULATION
There are two main uses for pipe insulation:
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To prevent heat loss: This will save energy and money and make using hot water more convenient, with proper pipe insulation hot water will be available as soon as you open the tap.
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For safety reasons: hot pipes can be dangerous, especially in rooms where small children play or in places where you might touch them accidentally. Pipe insulation can reduce the risk of scalding yourself on an unconcealed hot pipe.
COSTS AND SAVINGS
Rubber foam tube insulation is quite inexpensive, two metres of foam tube pipe insulation costs around
£3-£5 and most fibreglass products will cost around the same.
Thicknesses of thermal pipe insulation used for saving energy vary, but as a general rule, pipes operating
at more-extreme temperatures exhibit a greater heat flow and larger thicknesses are applied due to the
greater potential savings.
Poorly insulated pipes are responsible for annual non-recoverable heat losses of up to 40 of the net heat
demand. By insulating the distribution pipes these losses can be reduced to 12.
HOW TO INSULATE HOT WATER PIPES
For efficient pipe insulation it is best to rely on the experience of a professional plumber or heating
engineer who has the proper knowledge to identify hot pipes with potential for heat loss and to choose the
best kind of insulation.
HOW TO DIY PIPE LAGGING
(Please note that we recommend using professional help to obtain the best results possible)
Begin by cleaning the pipes and allowing them to dry completely before installing insulation to avoid
mould or mildew. Select fibreglass, foil, or tubular sleeve insulation. Tubular sleeve insulation is the
easiest to install, simply cut the desired length and snap it around the pipe. Use duct tape to join
seams and joints where the pipes change direction. Be sure to install the sleeves so the seam faces
downward. Install foil or fibreglass insulation with a ½ inch overlap, making sure to duct tape the
ends. Fibreglass insulation should be wrapped with plastic to avoid condensation drips.
All hot water pipes should be insulated, especially within 3 feet of the water heater. Fibreglass insulation is the safest to use with a gas water heater because tubular sleeve insulation is more flammable.
Both fibreglass and foil are capable of insulating pipes at an R-4 efficiency level which is advisable for
hot water pipe insulation, depending on their thickness. Foam often comes in pre-cut tubes of one
metre length and is usually rubber foam, while there are also other synthetic foams on the market.
Fibreglass comes in different shapes; there are shell coverings as well as sheets that would be
wrapped around the pipe. It is important that the pipe insulation is properly fixed to the pipe; loose
insulation will work less efficiently.
Look for the Energy Saving Trust Recommended label if you’re buying pipe insulation – it will help you
recognise the most energy efficient products.
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