Furnaces in unheated spaces

[carlosgw]

I seem to remember that condensing furnaces were not supposed to be installed in unheated (freezeing) space. But now I can not find anything one way or the other in manufacturer's installation manuals (I checked Carrier and Rheem). Anyone know any issues with installing gas fired furnaces (80% or condensing) in freezeing spaces?

 

[MintJulep]

There is a trap in the condensate drain. If it's cold enough, the condensate will freeze in the trap.

 

[carlosgw]

That can be addressed with heat tape.

 

[imok2]

If its a non condensing furnace you would probably drop the stack temperature below its dew point and corrode the stack and with a condensing furnace you would need to run PVC for the stack Also tou would need to use a warmer combustion air to get a decent temperature rise