I am in the middle of hooking up an outdoor wood boiler and have a question. I am installing the heat exchanger into my ducting and there are only two options. One is to install it into the return line but I think I will lose some heat that way plus I will have to make a place to put a new air filter above the exchanger (the present air filter is on the bottom of the furnace right at the blower). The other option ,which is the easiest, is to mount it under the A coil but this will put it right above the heat outlet from the oil furnace. It will be about 5 or 6 inches from it. Is this to close. The oil furnace I have is tall and has the return line and feed line both on top of the furnace so I don't have many options. I can make it work either way but the feed line with the A coil is the easiest. I can send a picture if it helps.