Quote:
Originally Posted by gtojohn
Something I always notice is the roof above the adjacent attic space will frost while this one doesn't.
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Frost on the inside of a roof is due to warm moist air leaking from the conditioned space. Fix those air leaks (there is always more than one) and you will save much more than by preheating furnace intake air.
I replaced an 85% efficient water heater hydro air system with a 95% efficient boiler with indirect water heater. My gas consumption decreased 24% for the same number of degree days.