Bryant Plus 90 Noisy Startup

[Tom Nehrer]

My 15-year-old Bryant Plus 90 has been making a buzzing sound on startup that can be so loud it sounds like a jackhammer in the basement -- or not. The noise level varies -- and goes away when the repairman comes.

Just after the thermostat clicks on, this buzzing can start, persist for a while, but when the unit has heated and the fan comes on, the noise stops.

Last year it was really loud, but the day the service guy came it was totally silent. Since heat went on in the fall (near Pittsburgh), it can be very noisy.

Any thoughts?

[paul52446m]

My 15-year-old Bryant Plus 90 has been making a buzzing sound on startup that can be so loud it sounds like a jackhammer in the basement -- or not. The noise level varies -- and goes away when the repairman comes.

Just after the thermostat clicks on, this buzzing can start, persist for a while, but when the unit has heated and the fan comes on, the noise stops.

Last year it was really loud, but the day the service guy came it was totally silent. Since heat went on in the fall (near Pittsburgh), it can be very noisy.

Any thoughts?

Have your repairman check the 24 volt coming back to your electronic board. It almost sounds like you are getting a relay chatter from low voltage or a bad set of contacts in a relay. Another thing that can make the noise is if one burner is lighting off just in front of the orifice instead out the end of the burner. Some times it will run like that for a minute or two then the flame will go out the end of the burner. Clean burners
check gas pressure Later Paul

[Tom Nehrer]

Paul, thanks for your tips. The service guy came and went over everything, including points you raised. True to form, it didn't make the noise when he came, so it was tough to trace. But it seems to have been a condensation buildup in a drain line that backed up to where the exhaust fan was hitting it. We'll see. Nothing looked wrong and it's quiet now.