I have a wood furnace next to my propane furnace. I bought all the duct pipe and 2 backdraft dampers needed to connect to my homes duct system.
My question is how far above my propane furnace, inside the plenum, do I install the 20x20 backdraft damper?
My question is how far above my propane furnace, inside the plenum, do I install the 20x20 backdraft damper?


![[Hearth.com] Backdraft damper install. [Hearth.com] Backdraft damper install.](https://www.hearth.com/talk/data/attachments/235/235624-383e91605f5c078bd502118fd2e62231.jpg?hash=BFiHf5k9TU)