Mini split to make up heat lost to hybrid water heater?
ripple963
| Posted in Energy Efficiency and Durability on
We have an 80 gallon State hybrid hot water heater in our finished basement (new construction). It keeps the basement really cool in summer, as it sucks heat out of the already cool basement (in Maine). My question relates to winter: should I use the minisplit that we installed in the basement to make up for the heat loss from the hybrid hot water heater; or should we run the hybrid hot water heater in “electric only” mode to stop it from eating up the heat?
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Replies
It is more energy efficient to use a heat pump for the winter, but installing one for only that purpose is probably not financially efficient. Can you fit a drain water heat recovery pipe?
In the summer it sounds like you need to get the air circulating and so that one spot is not so cool.
For the winter, the math says operating the water heater in electric mode will use 4 times as much electricity. If you should get to the point that your heat pumps cannot maintain the houses set point only then would I adjust the water heater to electric mode but the number of BTU the water heater takes is a small percentage of what is required to heat the house and you are in trouble without another heat source.
Walta
The water heater is going to "steal" heat from the heated part of the house through the floor. Whether it's better to let it steal that heat or produce it using resistance electric depends upon how you're getting that heat. A heat pump water heater typically has a coefficient of performance of around 3.5, so for every unit of electricity it consumes it provides 3.5 units of hot water. The remaining 2.5 units are stolen from the house. So the question is, are you better off providing those 2.5 units from the house heat or from electrical resistance?
In most places the house heat is more economical. As Walta notes, generally the amount of heat needed by the water heater is small compared to the heating load of the house so it doesn't tax the heating system overly. You might find that it makes the floors of the first floor rooms somewhat cold.