Hello, im heading into my second season with the VF100, I have it ducted into my LP furnace which is about 20 feet away, here’s the dilemma, connecting the VF to the LP is about 25’ of ducting, if the power ever goes out gravity flow will be limited if at all. So I can either have a manual air damper on the plenum that’s always open “wasting” heat into the unfinished basement or install some sort of damper that opens when the power goes out if that’s even a thing, I’ve been looking around on line and I can’t find anything that fits that description, anyone here have any thoughts?