So far this season, we've had enough sun to provide 90% of our hotwater,
from the 1,300 Watts of PV connected to the water tank's elements.
So, the A7 heat pump isn't a factor so far.
However, there is a little thermal heating in the area of the tank, due to heat losses.
The basement slab is around 65F most of the summer and 55 to 60F during most of the winter.
The upper part the basement walls get colder as the weather gets colder.
40deg F wouldn't be unusual.
My rough calculations for air flow say that all the basement air will be changed about twice an hour.
(when the fans are running).
After looking at the attic temperature plot lines for a few days,
I can't see any change when fans are turned on, or off.
That has to mean the attic has a lot more hot air available, than I'm using.
Otherwise, the attic temperature would drop within minutes of turning on the fans..
It sure seems like I need bigger fans..
Not gonna happen!
I've been thinking this over, and I'm starting to understand what it takes to heat up the basement.
I remember back in the days of cheap oil, we used to turn on the basement
baseboard heat during the winter.. I had a TV down there.
One thing I recall was how fast the basement play room would cool down,
after the heat was turned back down to 50F.. It was almost instant.