Hot air into crawl space
 

Has anyone ever heated a crawl space with a hot air panel?.
I have a south facing wall of about 30 feet in length and 5 feet below any windows which is ideal for the panel. And the most direct way of using the heat from the panel would be to duct the hot air to the farthest side of the crawl space and pull the cooler air from the other side to give some underfloor heating during daylight.
Here in New Mexico the average humidity is in the low 30% so we don't suffer from mold which was my primary concern.
Can anyone see any downsides?

Go for it.
Only problem I see is when it gets cold it's going to cool under the house, which can freeze pipes.

The plan is to use an Arduino controlled fan and dampers to only activate the heater when the panel temperature is higher than the crawl space. This could also be used in reverse in the summer to move the cooler night air into the crawl space to help the A/C out a bit.

Hi,
Here is a simple crawlspace solar heater I did:
https://www.builditsolar.com/Project...lySunspace.htm

https://www.builditsolar.com/Project...ating/0036.JPG

It was more of a test than anything else to see how well it would work, and it worked fine.
I've since used that wall for a more permanent solar water heating system, but the air heater worked fine.

Gary