I know this thread is old, but here is another Idea: pumping the hot air from the attic into the crawlspace.
What we have done is this:
- Its a california, bungalow-style house ~1000sqft.
- we connected the attic to the crawlspace with 2x 6" ducts + 40W fans.
- made sure, the attic-side pulls the air from the highest point of the attic, to make sure we get the hottest air.
- we have a vented crawlspace which gets pretty cold during winter (5-10°C).
- I am constantly measuring humidity & temp in crawlspace & attic.
- max temp diff in winter between attic & crawlspace is about 30°C.
We simply push the air into the crawlspace while not even closing the vents. When temp diff is above threshold. The pressure from the attic is
enough to keep cold air out from our 4 crawlspace vents.
This heats up our crawlspace by about 5°C. This is noticeable inside and basically feels like floor heating in the entire house. Its really nice
.
I haven't done any calculations on it or anything. Its mostly about how it feels like for us right now.
I am sure a lot of improvements could be made on this. E.g. closing some of the vents in this situation.
But first need to make sure that doesn't cause crawlspace air to flow into the house through cracks in the floor.
The advantage of it is that its really low effort to do this. and you don't get in touch with the air from the attic. I have checked,
if there is any increase in humidity in the crawlspace when doing this. But the humidity is decreased,
because of the heated air from the attic. And the air from the attic is really dry as it is the
same outside air as the one from the crawlspace.
