Hey guys. Looking for some help or guidance here. Just picked up a Englander 28-3500 Add on today. Been reading up quite a bit about this thing and finally pulled the plug. Planning on doing the install this weekend and have a few questions. Let me give you a brief run down of my situation.. My house is brand new. Just moved in the end of October. I have a 2600 sq ft 2 story, very open floor plan and 9' ceilings in the first floor and a full basement with Superior walls. Primary heat for the 1st floor is FHA propane and 2nd floor is an electric heat pump. When i built the house, i had a masonry chimney ran to the basement for plans of adding a woodstove to supplement heat mainly due to the rising costs of energy and also because i live on a wooded lot with endless firewood. Recently while Christmas shopping i came across the Englander add on and immediatley fell in love with the fact that i can tie this into my current ductwork. Now here is the issue: my house is about 55' long. FHA furnace is at one far end of the house. The supply and return ducts run down the each side of the center beam for the entire length of the house. Located at the complete opposite end the the house is the chimney. Englander wants this add on to be piped in at the furnace. But since my chinmey is 55' away, clearly that isn't gonna happen and running a duct from the add on all the way down to the furnace doesn't seem logical. I am planning on hooking into the supply line at the very end of its run, closet to the chimney, but farthest from the propane burner. This will push the hot air from the add on torwards the propane burner. SInce its not a good idea to push the hot air into the propane burner, i want to put a balancing damper into the supply duct at the propane burner. That way when the add on is blowing, the damper at the propane burner is closed. Sounds easy right?? BUT WHERE DO I GET A BALANCING DAMPER??? My duct measures 10" in height and 20" wide at the point where i want to put the damper. I can't for the life of me find anything like this. Any ideas? Or will i be forced to go to a metal shop and have one made?