Update Bulletin No. 458
you for
your interest
in writing to me about
devices to improve your
summer comfort and save
energy at the same time.
One of the best devices
to accomplish this is a
Jim Dulley
heat pump water heater
(HPWH). What one does is draw heat from
the room air and then transfers this heat to the
water in the water heater tank. As a result,
the air in the room (it can also be ducted to
other areas) is cooled and dehumidified. If
you now have an electric water heater, installing one may make good economic sense
and provide a reasonably quick payback. If
you have a gas water heater, it probably will
take a longer time period to payback its initial
cost. The E-Tech HPWH’s made by Applied
Energy Recovery have been available for
many years and have proved performance.
If you live in a warm climate and use a
central air conditioner, a desuperheater unit
might be a good choice. See below to estimate
about how much you might save by using one.
Desuperheaters work by using the heat from
the hot air conditioner refrigerant to heat your
water instead of just losing it outdoors. In a
freezing climate in the winter, it is important
to care for the unit properly to avoid freeze
damage if water is left in the heat exchanger.
The various designs have different methods
for taking care of this problem. All of the
designs that I have listed are equally effective.
Almost all of the geothermal heat pump
manufacturers offer optional desuperheater
coils for their whole-house systems. Several of them also sell stand-alone geothermal water heaters. For one of these to pay
back quickly, you should have a large family
with high hot water usage patterns.
There are several other efficient methods to improve your indoor comfort. Adding a dehumidifying heat pipe Z-Coil, by
Heat Pipe Tech., to your existing air conditioner can lower the humidity level indoors
without sacrificing efficiency. Another option is the Santa Fe, by Therma-Stor, that
uses a super-efficient dehumidifier
to dry the air. It can also bring in
fresh outdoor air efficiently.
How Much You can Save with a Typical Heat Recovery Desuperheater Unit
An average family can save 20% to 40% on
annual water heating cost; and improved cooling
performance from an air conditioner or heat pump.
This will lower your utility bills and provide
greater peak cooling capacity on the hottest
Your actual savings depends on several factors. They include —
1) How many people live in your house.
2) How much hot water you use each day.
3) What time of day you use your hot water.
4) How much your electric company charges per
kilowatt hour.
5) How long your air conditioner or heat pump
runs each day.
6) How big and how efficient are your air conditioner or heat pump and your water heater tank.
As you can see, the number of factors and
their interaction make it very difficult to precisely
Hot Water Cost and Savings — Table 1
Daily Hot
Water Usage
Annual Water Heating Cost per Kw
predict the actual cost savings, but these compiled results from actual home installations will
give you a rough idea of “typical” costs and savings.
To get an idea of the approximate savings
you can expect from your heat recovery unit,
use tables 1 and 2 to estimate the water heating
savings and air conditioning performance improvement savings.
AirConditioning Improvements
Savings — Table 2
40 gal.
3 ton
55 gal.
4 ton
70 gal.
5 ton
85 gal.
100 gal.
The annual cost includes both heating up cold water to replace the hot water you use
and the loss of heat from your water heater and piping between your uses of hot water.
Calculate the savings by multiplying the annual cost figure from the table by the fraction of the year that you operate your air conditioning (i.e. 6/12 or 8/12 or 4/12 etc.)
Payback Example — for a family of 4 with a 3 ton A/C, 6 months of cooling and 9.0¢
per KwH electricity
Average installed cost of heat recovery
Less: Hot water savings (6/12 x $471 = 235.50)
Less: A/C improvement savings (6 x $13 = $78.00)
Net First Year Cost
The table assumes 8 hours of air-conditioning per day on a SEER
9 unit and sufficient hot water usage to keep the heat recovery
unit running. Older, less efficient units will increase the rate of
monthly savings. The newest super-high efficiency units will tend
to reduce the savings.
Calculate savings by multiplying the monthly figure from the table
by number of months per year that you run your air conditioning.
These savings result from the freon refrigerant being precooled
when it first goes through the desuperheater to warm the water.
Since some heat is already removed, there is less heat transfer
load on the outdoor condenser coils. Since newer, efficient central air-conditioners have very large condenser coils to start with,
the savings with a newer model is less than for an old one.
Selected Manufacturers of Devices to Cool Home/Heat Water for Better Comfort
APPLIED ENERGY RECOVERY SYS., 6670-A Corners Industrial Ct., Norcross, GA 30092 - (770) 734-9696 www.aeretech.com
type - add-on remote HPWH
heat source - room air
*coefficient of performance (efficiency) - 3.5
model - E-Tech WH-6BX-1
heating capacity - 6,000 Btuh
cooling output - 4,000 Btuh
dehumidification - 1.0 pint/hr.
hot water recovery rate - 10 gal./hr.
dimensions - 15.6" × 8.5" × 26" high
features - This add-on HPWH has a tube axial fan so the cool, dry air can be ducted to other rooms, into your central duct system
or vented outside. There is an automatic freeze-protection switch-over to resistance heating when the room temperature drops below
45°F. There is a fast recovery option that automatically switches the top resistance element on after high volume usage periods like
in the morning. The basic design has been around for many years and is well proven. In the winter, it draws extra heat from your
utility/furnace area to heat the water or the electric resistance element in the tank heats the water. This is an ideal size for the typical
family. Installation to the existing electric water heater is relatively easy. Price of this model is about $700.
* Coefficient of performance (COP) of 3.0 means you get three dollars worth of heat for each one dollar on your electric bills. A higher COP is better.
Update Bulletin No. 458
page 2
type - add-on (tank) HPWH
heat source - room air
coefficient of performance (efficiency) - 3.5
model - E-Tech R-106K4
heating capacity - 6,000 Btuh
cooling output - 4,000 Btuh
dehumidification - 1.0 pints/hr.
hot water recovery rate - 10 gal./hr.
dimensions - 15.6" × 8.6" × 26" high
features - This add-on HPWH mounts on top of the water heater tank to save space and for the best efficiency.
This high efficiency results from very little energy loss from the HPWH unit to the water heater tank below it. Since
it mounts on the tank, the plumbing to attach it to the water heater tank is more complex than with the WH-6BX1 model, so professional installation is recommended. This unit, like the WH-6BX-1, uses HCFC-22 refrigerant.
HCFC-22 has a lower impact on the ozone. Most of its features are also similar and it functions in the same way.
All E-Tech models require a standard 230-volt electric line which will be available near the water heater if you have
an electric water heater. Price is about $1,000 plus installation.
ECONAR ENERGY SYSTEMS CORP., 19230 Evans St., Elk River, MN 55330 - (800) 432-6627 www.econar.com
type - add-on remote HPWH
heat source - earth
coef. of performance (efficiency) - 3.3
model - GD-360
hot water recovery rate - 44 gal./hr.
dimensions - 15" × 8.6" × 26" high
features - Can be used with a central geothermal heat pump. Prices vary with size and installation details.
ENVIROMASTER INTERNATIONAL, 5780 Success Dr., Rome, NY 13440 - (800) 228-9364 www.enviromaster.com
type - Integral HPWH
heat source - inside house
cooling capacity - 3,500 Btuh
model - WattSaver
first hour rating - 52 gallons
dimensions - 22.2" dia.× 60" high
features - This model is easy to attach to an existing water heater. It is call “110” because it operates on standard 110-volt house power
so no special new wiring is required. It has an eight-foot cord so it plugs into a standard electrical wall outlet. It also dehumidifies at
a rate of one quart per hour when it is running. The energy factor (EF) is 2.4. The best standard electric water heater has an EF of .95.
It has a seven-year limited warranty. The typical installed price of the unit is about $1,500.
ENVIRONMENTALLY ENGINEERED EQUIP., 9852 Monroe Dr., Dallas, TX 75220 - (800) 428-7722 www.heatharvester.com
type - desuperheater
heat source - hot refrigerant from central a/c
pumps - one
model - Heat Harvester
dimensions - 25" × 12" × 6.5" high
warranty - 1 year
features - These units are primarily designed for light commercial and commercial applications, but they can be feasible for a very large
residential home with an air conditioner of five ton capacity or larger and large hot water needs (large family). (Uses thermistors in
the water lines to control the pump. When the water temperature in the tank reaches the desired point, the small pump shuts off. The
water pump uses about 60 watts of electricity. Contact the company for prices on specific models/capacities. These units will require
professional installation.
HEAT PIPE TECHNOLOGY, 4340 N.E. 49th Ave., Gainesville, FL 32609 - (800) 393-3464 (352) 367-0999 www.heatpipe.com
type - desuperheater
heat source - hot refrigerant from central a/c
pumps - none
model - Hot Plate (see page 4)
dimensions - 22.5" octagon x 2.5" high
warranty - 5 years
features - This unit is designed to fit underneath an existing electric water heater with minimal plumbing modifications. It uses two threeway valves for flushing and connection to the existing water heater (all hardware and fittings are included in kit. It will heat water up
to 160°F, but 120°F is the recommended temperature for the best efficiency and lowest overall water heating costs. Price is $400.
type - dehumidifying heat pipe
power usage - none
warranty - 5 years
models - Z-Coil and AHR Modular unit (see page 3) Price of a 3-ton Z-Coil is approx. $870. AHR unit prices vary with size/features
NYLE SPECIAL PRODUCTS, P.O. Box 1107, Bangor, ME 04402 - (207) 942-2865 www.nyletherm.com
type - add-on remote HPWH
heat source - inside house
cooling capacity - 7,000 Btuh
model - Nyletherm -110
hot water recovery rate - 10 gal./hr.
dimensions - 16"×12.6" × 21" high
features - This model is easy to attach to an existing water heater. It is call “110” because it operates on standard 110-volt house power
so no special wiring is required. It has an eight-foot cord and plugs into a standard electrical outlet. It also dehumidifies at a rate of
one quart per hour. It has a one-year limited warranty. The current price of the unit is about $900.
THERMA-STOR PRODUCTS, PO Box 8050, Madison, WI 53708 - (800) 533-7533 (608) 222-5301 www.thermastor.com
model - Ultra-Aire
air flow rate - 220 cfm
power usage - 782 watts warranty - 5 years
features - This indoor air quality/comfort device (see below) combines fresh air ventilation, air filtration and high-capacity humidity
control. The control panel contains a fan/filter switch that allows continuous air circulation and filtration independent of dehumidification. There is a dehumidistat with settings from 20% to 80%. Prices range from $2,000 to $2,300 depending on features and options.
They also make a super-efficient large dehumidifier “Santa Fe” which I use in my own basement.
TREVOR-MARTIN, 4151 - 112th Terrace N., Clearwater, FL 33762 - (800) 875-1490 (727) 573-1490 www.trevormartincorp.com
type - desuperheater
models - Aquefier, Dynamax, HotTap
heat source - hot refrigerant from central a/c
features - This company sells all three models. Although each has a different design, they all function in a similar manner and are priced
about the same - $600. The small water circulation pump operates on 230-volts and there are models for straight central air conditioners
or heat pumps. To determine which is best for your specific home, contact the manufacturer to discuss your system.
WATER FURNACE INTERNATIONAL, 9000 Conservation Way, Ft. Wayne, IN 46809 - (800) 934-5667 www.waterfurnace.com
type - geothermal heat pump with desuperheater
heat source - earth
coefficient of performance (efficiency) - 2.5 to 3.5
model - Premier Series
water heating capacity - depends on size
dimensions - many models and varies with capacity
features - Their desuperheater option is most effective in conjunction with a geothermal heat pump (over 2.5 tons in capacity) using
the same ground loop or open water source. This allows it to recapture the heat that the geothermal central conditioner transferred
to the ground. Has water temperature settings from 110°F to 135°F.
comments - If you do not already have a geothermal heat pump with a ground loop installed to which you can connect an optional
desuperheater, the installation costs will be substantial. These geothermal systems are the most efficient air-conditioning systems
available. Prices vary depending on size and installation details required for your site.
Update Bulletin No. 458
page 3
Geothermal Heat Pump-A/C Units with Optional Desuperheaters
Since the ground stays fairly constant in
temperature throughout the entire year, a geothermal heat pump will heat and cool a home
about two to three times more efficiently than
a standard air-to-air heat pump.
Both Econar and Water Furnace offer
complete standard geothermal heat pumps
with desuperheater coil options to heat your
water with the waste heat from your house
during the summer cooling mode. During the
winter, the heat is drawn from the warm
ground loop buried in your yard or well.
Econar Geothermal Heat Pump-A/C
AHR Modular Air Handler
by Heat Pipe Technology
Econar also offera stand-alone geothermal water heaters. These are economical
methods to heat water using electricity.
How an AHR works This is a blower unit, with
an optional electric strip heating
element in it, that mounted on
top of a Z-Coil. This will
provide a complete system. It
uses the outside heat pump/air
conditioner in the cooling mode
and the heat pump and/or electric
resistance strip heating in the
winter. Three sizes range from 2
to 5 tons cooling capacity.
How a Z-Coil works The return air from
your house is precooled by
the heat pipe in the
Z-Coil. When this Return
precooled air
crosses the a/c
cooling coil, it is
supercooled for
extra moisture removal.
This supercooled dry air
passes over the other end
of the heat pipe and is
reheated. No extra
electricity is used.
Water Furnace Geothermal Heat Pump-A/C
Z-Coil only
by Heat Pipe Technology
Air conditioner evaporator
cooling coil
air to
Extra humidity
pulled out of air
Water Heater Efficiency Tips
1) Lower the thermostat to 120 degrees
from 140 degrees. This action can save
as much as $45 per year and reduce
the risk of burns from tap water.
2) Wrap the water heater with insulation.
If the water heater is located in an unheated area, wrapping it can save up
to $1 per month.
3) Drain a few gallons of water from the
bottom of the tank each month to remove sediment.
4) Install heat trap fittings in the cold and
hot water pipes at the top of the water
heater tank.
5) Fix leaky faucets promptly. As you can
see below, a faucet that leaks 30 drops/min. = 84 gal./month = 18
60 drops/min. = 168 gal./month = 37
6) If you are going to be gone for more
than three days, switch off the power
to an electric water heater at the circuit breaker panel or set the thermostat lower on a gas water heater.
Schematic of a Typical Heat Pump Water Features 1) Has high efficiency and reliability.
Heater Installation
is retained
installation is
and required by
code in some areas
Cool, dehumidified
air is exhausted into
utility room or
basement or it can
be ducted to
another room
2) Is a small size to fit most basements and utility rooms.
3) Tube axial evaporator fan allows cool, dry air to be ducted
to other areas or vented outside for fresh air ventilation.
4) It can be installed in many orientations with single coaxial
plumbing connections.
5) Automatic switch-over to resistance heating when ambient
temperature drops below approx. 42 degrees *.
6) Optional fast-recovery installation automatically switches
top resistance tank element on after large water draws to
minimize hot water outages.
7) Offers automatic high pressure reset.
* At 42 degrees, a switch turns off the compressor and the
pump activates the defrost mode. In he defrost mode, the
resistance heat operates until either the thermostat is satisfied of the ambient air temperature rises above 42 degrees.
The evaporator fan operates in the defrost mode to speed
up the defrosting of the coil.
Applied Energy Recovery
Model WH-6BX-1
Update Bulletin No. 458
page 4
Hot Plate Heat Exchanger
by Heat Pipe Technology
Dynamax by Trevor-Martin Corp.
water out water in
Tempering valve
one required
3-way valve
Heat exchanger
T & P valve
Hot water
Air conditioner
Water pump
Specifications • Dynamax units are housed in a .04 thick
aluminum cabinet painted with a scratch
resistant enamel.
• The drive pump is water lubricated and water
cooled. It operates at 3,250 rpm, 1/40 hp,
.38 amps on 220-240 volts. It delivers a
water flow of 12 gpm and a head pressure of
10 feet of water.
• Has an automatic water shut-off at 140° and
hot gas control set to 115°F.
• Uses all copper heat exchanger to meet HUD
and UL standards.
Nyletherm 110 HPWH
Unit Specifications:
Cooling output - 7,000
Btuh when running - heat
goes into warming water
Recovery - 15 gallons per
hour at 120 degree tank
water temperature
Maximum water temperature - 140 degrees
Dehumidification - one
quart per hour
Electrical Specifications:
Volts - 110
Amperes - 7.25
Type - one phase, 60 Hertz
Installation Requirements:
Water heater tank much be clean with no sediment.
The existing water heater tank must be the proper size
for your family’s needs. The tank drain valve must
be accessible
High efficiency, safe, reliable, virtually no maintenance. It can be wall or floor mounted for convenience
Installation Hints • Use the Dynamax installation kit (IK-5) in the
top or bottom of the tanks.
• Take water from the drain and return below
relief valve. This method may nt be satisfactory with old tanks because particles in the
bottom of the tank are difficult to remove and
may clog the lines and pump.
• Connecting the water line from the heat
recovery unit directly into the hot water line
from the tank to the house will cause a lack of
hot water and water temperature fluctuations.
• Unit should be protected from freezing.
Freon in
Solder &
Freon out
to condenser
3-way valve
Enviromaster Model WattSaver
Full “drop-in” replacement for 50 gallon electric water heater:
Microprocesser controoled
Same footprint
Identical electrical hookup
No additional plumbing requirement
EF Rating = 2.4
Designed for single trade installation.
Uses refrigeration compressor – robust,
proven, inexpensive, and compact, yet
shroud for
easy access
sufficient capacity for meeting most
to plumbing
water heating demands.
and electrical
Auxiliary electric elements provide
quicker recovery when demand requires
No pumps required
Heat pump unit shipped fully charged
and operational
Design employs a conventional hot
water tank; simply make plumbing con50-gallon
nections and electrical hookups.
water tank
Can be installed anywhere in your
Condensate-free option available
Quiet Operation
Typical payback from 2-5 years (dependent upon kWh rates and water usFoam
7-Year Warranty On Tank and Heat
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