Ok, I have a keystoker A120, and I'm looking to tie this into my cold air return. I can buy a unit that is a box, with a space for a removable filter in it, and a bend up that you would then add ductwork to. It is $90, but I don't think it will fit in the space beneath the motor. It seems like I would be better off making something myself. Another option would be to draw up all my measurements and have the local sheet metal place manufacture the duct work for me. Has anyone done this before? Or have any sources to buy these 'filter boxes' ? Or would it be in my best interest to just call a local heating company and let them build and assemble the stuff. It seems like a pretty small job for them though. Thanks for any input you can provide.
Actually now that I've found images of what I'm thinking of online, it looks too much for me to build myself. I'll just have to find a local place that can sell me the pices I need in the sizes I need.
I do have another question though that maybe somebody can help me answer. I had existing ductwork in the house for my oil furnace. I tied my keystoker into the ductwork by running 8" round pipe from the coal plenum into the oil plenum. There is 8x12 duct that runs up for the cold air return. Should I tie into that cold air return with 8x12 duct, or would it be sufficient to tie into it with 8" round since I'm limiting it to 8" round on the output. There will be a couple of turns to get from one cold air return to the other, so that could be a reason to go with an 8x12 or maybe even larger rectangular duct instead of 8" round. 8" round is considerably cheaper than the 8x12 rect.