Gas furnace replacement during large renovation
I have a 10 year old 60,000 BTU Trane forced air unit located in a freezing vented tiny attic in Zone 6a. It was a diy install by previous owners. Trunk & branch system with every single duct is 6″ flex. No mastic in sight and crap job as a whole. Minimal insulation. This does a surprisingly ok-ish job at heating the main floor but doesnt do much for the basement. I want a new unit installed in the finished basement and having new indoor ductwork installed inside the warmth. (Mom is taking old unit)
Not one company in this town will do a manual j or the other manuals. One said they would and they faked it, took them 5 min to ‘calculate the J’ 😖 gas is cheap here, electricity is high. And the heating the leaky old hardly insulated 1953 house is beyond insane. A large renovation is poised to take place. Gut to the studs, about R10 continious exterior insulation, r13 cavity fluffy insulation with zip sheathing air sealed & housewrap. (There is currently 0 insulation in the walls) Metal roof with a layer of zip on sheathing to kill truss thermal bridge attic insulated to r49 except at my 2″ of space at exterior wall top plates will be r20 🥺. Attic airsealed and emptied of mechanicals plus booting out the 3 can lights in favor of track lighting. Replacing five of the thirteen 10 year old leaky double glazed vinyl windows with three solid picture windows, 1 glass block, And one window reverting back into solid wall. Replacing 2 of the 3 doors.
I’d say even if the builders do a poor job at my requested extra attention to airsealing and such, this house will still be in a whole new realm of warmth & comfort.
HVAC crews are all giving me estimates to replace & move the 10 year old 60,000 btu furnace with a new energy efficent 60,000 btu furnace. That has to be wrong. My reading says I should be downsizing it because of the renovations. What do you say? The main floor + finished basement is 1,750 sq ft together. But that # is as a whole, including inside walls and everything. 8ft ceilings on main floor. 7 1/2 ceiling in basement. My gut says buy a 40,000 btu? (But I really dont know anything) idc about the ac, the heat is way more important!! Photo of sticker in existing unit included
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