Hybrid heat-pump hot water heater cooling effects
We have a GE hybrid heat pump hot water heater in the non-partitioned 1100 square foot basement of our pre-certified PassivHaus home in northern NJ.
We’ve found that when it’s operating as a heat pump, it exhausts enough cold air that it actually cools the basement significantly.
The first and second floors each have their own ductless mini-split heat pump heads. The basement and dormered attic don’t have heating or cooling, but they do have ERV vents and returns. During the Summer the whole house, including the basement, top to bottom, measured within 2 degrees. But this winter we’re seeing 5 or 6 degrees lower temperatures in the basement.
Some of that could be due to our not-quite-final sealing of envelope penetrations in the basement. But some of it is due to the heat pump mode.
Proof? When I switched the hot water heater from hybrid mode to resistance-element-only mode the temperature down there rose a couple of degrees.
I bought a small 6 cubic foot chest freezer that my wife wanted, and placed it next to the hot water heater, thinking that its heat exhaust might offset the hot water heater’s cooling effect. It’s not helping. Apparently, the freezer’s too small or too efficient to have any effect.
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