Heat pump water heater moisture issues – GreenBuildingAdvisor

Recently saw this article from BSI:

https://buildingscience.com/sites/default/files/document/BSI-150_Alice%20Cooper%20Does%20Heat%20Pump%20Hot%20Water%20Heaters_%C2%A9_0.pdf

BSI stuff is usually well researched but there are some real issues with the article. When they are doing the calculations for heat extracted from the house air, they don’t take into account that all exterior walls are radiating heat into the house, a large volume of air like that barely budges in temperature.

They also don’t mention that a HPWH in a 60F dewpoint place is actually dehumidifying the basement, the issue is there is not enough mixing with house air.

It is good they are pointing out that there can be issues with installs and installation instructions could be better to avoid some pitfalls.