Welp, the house I bought has a huge dinosaur of a furnace. It's 125k btu, but the thing is probably 7ft long, 5ft high and 4ft wide. I am betting it's from the 1960s or 70s. My furnace guy says it will probably run, but it will kill me on the gas bill. I am thinking, yeah, I bet it will.
So anyway, The ductwork in my house is pretty stupid. the main floor is normal, but the upstairs is fed by a tiny 8" pipe that goes all the way to the attic and branches into 5 more 8" pipes and blows down into all 5 bedrooms. Needless to say, I am betting not much is gonna come out of these ducts... But with supplimental heat rising from the downstairs, who knows.
I am having trouble deciding if I should just replace the 125k btu furnace with a modern one, or just replacing it with a smaller one, and putting a second furnace in the attic (since all the ducts for the upstairs already congregate there...
I wonder how two medium furnaces compare to one big one in gas use. This huge old house only has me an my wife, so we'd probably never run both zones at once, so I bet it would be cheaper.
Anybody else been down this road?
I replaced a dinosaur of a boiler last year for a friend,and the oil he saved was worth it. You can run a new one the right size for the house,just run a second zone for the upstairs with it's own thermostat. Have you tried to fire it up yet,you might be surprised how much air comes out of them 8" pipes.
I would run the 2 separate furnaces. and put air conditioning upstairs. you will save in the long haul especially with the high efficiency stuff they have today. or start with a new one upstairs for now, and use the old one for the lower level, until you see how much fuel it uses.
Check with your local utility company and see what sort of incentives they have for upgrading to a new, more efficient system.