I live in Upstate NY and in the winter it gets below 0° F.
I currently have baseboard water heating throughout my home. Prior to this I believe there was a gravity furnace which supplied the house with heat.
I am hoping to switch to a regular furnace for two main reasons:
- I would really like to get central A/C in the future
- I strongly dislike the idea of water lines everywhere in my house; copper does fail eventually
Right now we have 2 zones, upstairs and downstairs, which would be nice to maintain.
My 1940 home has a full basement and a full attic in which I can stand upright.
I would like to have a basement furnace which heats the downstairs. It will be trivial to run the supply lines and cold returns in the walls above the baseboard trim. This would allow me to remove the downstairs zone from my boiler.
I would also like to have an attic furnace to heat the upstairs. I feel that this would be easier than trying to run HVAC upstairs from the basement and it would make dual-zones easier to achieve. I think the supply lines would be do-able but properly doing the cold air returns would be a headache.
My understanding is that a high efficiency furnace has a condensate reservoir which gets pumped out through a 1/4 tube whenever it fills up; much like a dehumidifier with a built-in pump. Would this be a freezing risk? My attic does get below freezing.
Assuming I have insulated supply runs, would my attic get heated by the furnace and cause ice dams on my roof?
I do have some space on the second floor which can fit a furnace, would this be a better choice?
Best Answer
Since you have some space in your attic, and you seem set on installing the furnace up there, I think it would be easy enough to make a small room just for the furnace. I did that in our new addition, as the dedicated furnace for the addition was an afterthought after running ductwork over from the original furnace location turned out to be impractical. We put it in the attic next to the second level, but if the attic is above, it should work just the same.
We simply made a room large enough for the furnace and to have some work space around it. Coordinate with the furnace installer in how they're going to place it, and keep in mind which direction the filter needs to come out to be changed. Then simply build some 2x4 stud walls around the furnace at either 16" or 24" spacing. This allows you to use paper faced batt insulation so you can leave the one side if the wall just open. The other side should then have a continuous vapor barrier installed and probably sheetrock for fire protection. If you're going to install a high efficiency furnace, it will have its own combustion air supply, so you don't really need to worry about letting air in too much, otherwise, obviously, you will need to make sure there is an air supply there. If you're taking the room all the way up to your roof, make sure to leave space for venting in between your insulation and the underside of your roof.
Depending on how you will be situating things, think about the easiest method to seal around the ductwork. It may be best to install the ductwork first, then build walls, then install the furnace, but based on your situation, a different order might be better.
With this setup, your furnace will be at least in an insulated space, and it will keep itself warm in there to some extent. It might be worthwhile to remove the floor insulation underneath your room to get more heat in there as well. Keep the condensate drain plumbing within the insulated areas to keep it from freezing. You may end up running ductwork through non-insulated areas, in that case, consider getting the ductwork spray-foamed after installation.