Jack Fowler wrote:With the dust I always had a big concern for explosions
Venting your dust collector effluent back into the shop should be ok, if it's well filtered, like GW's.
Jack Fowler wrote:, but the fumes from the varnish/stains/paints, I did not only have concerns with explosions, but with health problems. I was thinking about a heat exchanger for the intake side to see if I could make that work, but he started spending his winter months in a warmer climate.
Even the best heat exchangers will only do so much. At best, they will meet you half way, so, if the incoming air is 30 degrees F, and the outgoing 70 degrees F, you could raise the incoming air to 50. Which will still need some heat added to make it comfortable. It's better than nothing if you're heating with fuel that costs you money, but not by a whole lot.
I have seen homemade heat exchangers that did better than that, but they took a whole lot of time to make, and did not reach peak efficiency unless they were run for some hours continuously.