Hello, I have a Bryant plus 80 2spd. Furnace [basement installed] that's aprox. 9 years old. It doesn't seem to be working properly [rarerly shuts off, constantly cycling] when it gets real cold and is flashing a code 31. The blower wheel [motor] in the front has been noisy for a while and I plan on replacing it. Not sure what it's called [low speed, hi speed etc.. ] could this possibly be my problem? I've replaced the flame sensor twice and the igniter once since I've owned it. It will reach the set temp. but it seems like it's always running. Looking it over I noticed holes [rotted out] in the exhaust pipe, it's about a 3 foot section that has a "T" in it for the hot water heater. I took it off and rapped it in duct tape for now until I can replace it. Will this be safe until I can replace the pipe? I don't know how long we've been breathing carbon monoxide... :(. Any advice would be appreciated.