Should I try to use ERV exhaust for Heat Pump Hot Water Heater? – GreenBuildingAdvisor

I guess I wasn’t clear about the ductwork. I would use a heat pump hot water heater that has a round duct inlet and outlet for either ducting to outside or some other space.

I would run the ERV exhaust duct basically into the heat pump inlet duct. I would run the heat pump outlet duct out to the outside exhaust terminal.

However, if the heat pump hot water heater needs 300 CFM of air to pass through it and the ERV is only exhausting 100 CFM, it won’t work.

So in my mind that is the weak spot of the idea.

Yes, the exhaust air can get colder than the basement room temperature so I wouldn’t want to use uninsulated duct work.

The other idea about a dedicated space sealed off where the ERV exhausts into that room would be possible, but I don’t have an area available to do that in. To make this work, the room itself would have to vent to the outside as well. It seems like this might be a viable way to do this for someone though. In my case, the ERV runs continuously and you would probably need to do that in order for this to work.