Just bought a new 4100i to replace a 30+ yr old Appalachian insert. Doing the install myself, with a helper. Question for you experienced guys, is it advisable to block the insert up off the hearth base...or best to sit it right onto the bottom? The previous insert sat flat on the bottom. I find the flue liner, that I installed 4 yrs ago...is too short to reach top of new insert...so I need to add in a piece.
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