To keep basement warm – keep away from heat pump water heater?
StuartKrantz
| Posted in Mechanicals on
We are building an energy efficient home (ACH 0.8 or better at 50 pascals) and I want to avoid a water heater heat pump because I want to put my shop in the basement and I don’t want to lower the temperature in the basement. Am I thinking about this issue correctly considering the energy these heat pump water heaters save? We plan on a net zero energy home using solar. [email protected]/954-732-3347
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Replies
Stuart,
You are correct that a heat-pump water heater will lower the temperature of your basement. If you don't like that feature of heat-pump water heaters, you should choose a different type of water heater. For more information on this issue, see Heat-Pump Water Heaters in Cold Climates.
The amount of temperature reduction is a function of how much hot water you use, and the total thermal mass inside the insulation in the basement, and the amount of heat source in the basement (active heating, or warm mammals + lighting, solar gain, etc.). In a typical home the net average temp reduction is less than 2F, but in a net zero energy home it could either less, or more, depending on the particulars.
A heat pump water heater also behaves as a dehumidifier, and will lower the amount of mechanical dehumidification &/or ventilation required to keep the indoor air humidity within healthy levels for both occupants & building.