Heat Controller, Inc. | HEV/H SERIES | Installation, Operation & Maintenance |
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HOT WATER GENERATOR
The HWG (Hot Water Generator) or desuperheater option provides considerable operating cost savings by utilizing heat energy from the compressor discharge line to help satisfy domestic hot water requirements. The HWG is active throughout the year, providing virtually free hot water when the heat pump operates in the cooling mode or hot water at the COP of the heat pump during operation in the heating mode.
Heat pumps equipped with the HWG option include a built- in water to refrigerant heat exchanger that eliminates the need to tie into the heat pump refrigerant circuit in the field. The control circuit and pump are also built in for residential equipment. Figure 14 shows a typical example of HWG water piping connections on a unit with
The temperature set point of the HWG is field selectable to 125°F or 150°F . The 150°F set point allows more heat storage from the HWG. For example, consider the amount of heat that can be stored by the HWG when using the 125°F set point, versus the amount of heat that can be generated by the HWG when using the 150°F set point.
In a typical 50 gallon
Using a 125°F set point, the HWG can heat the lower 40 gallons of water from 100°F to 125°F, providing up to 8,330
Typically a single tank of at least 50 gallons (189 liters) is used to limit installation costs and space. However, a dual tank, as shown in Figure 21, is the preferred system, as it provides the maximum storage and temperate source water to the HWG.
It is always advisable to use water softening equipment on domestic water systems to reduce the scaling potential and lengthen equipment life. In extreme water conditions, it may be necessary to avoid the use of the HWG option since the potential cost of frequent maintenance may offset or exceed any savings. Consult Table 3 for scaling potential tests.
Figure 14: Typical HWG Installation
| Hot Outlet | Cold | |
| to home | Inlet | |
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| Shut Off |
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| Valve #1 |
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| Shut Off |
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| Valve #4 |
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| Upper |
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| element to |
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| 120 - 130°F |
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| [49 - 54°C] |
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| Lower |
| Powered | element to | |
| Water |
| 100 - 110°F |
Heater | [38 - 43°C] | ||
Valve #3 |
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Shut Off |
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Valve #2 |
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| Field supplied 3/4’ brass nipple and ‘T’ | ||
Insulated water lines -
5/8” OD, 50 ft maximum (one way) [16mm OD, 15 meters maximum]
Figure 15: HWG Double Tank Installation
Hot Outlet to
house
btu’s of heat. Using the 150°F set point, the HWG can heat the same 40 gallons of water from 100°F to 150°F and the remaining 10 gallons of water from 125°F to 150°F, providing
Cold Inlet from
Domestic supply
Hot Outlet
Cold Inlet
a total of up to 18,743 btu’s of heat, or more than twice as much heat as when using the 125°F set point.
Dual element electric water heaters are recommended. If a gas, propane, oil or electric water heater with a single element is used, a second preheat storage tank is recommended to insure a usuable entering water temperature for the HWG.
WARNING!
WARNING! A 150°F SETPOINT MAY LEAD TO SCALDING OR BURNS. THE 150°F SET POINT MUST ONLY BE USED ON SYSTEMS THAT EMPLOY AN APPROVED
| Upper element to 130°F [54°C] | |
| Valve #1 | (or owner preference) |
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| Valve #4 |
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| Powered |
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| Water Heater | Lower element to 120°F [49°C] |
| Unpowered |
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Water Heater |
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Valve #3 |
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Shut Off |
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Valve #2 |
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| Field Supplied 3/4” brass nipple and “T” | |
Insulated water lines - 5/8” OD, 50 ft maximum (one way) | ||
| [16mm OD, 15 meters maximum] |
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