Issue with Trane XV80 - banging noises after shutdown

GeorgeM22

Hello, I'm a homeowner. I have a Trane XV80 oil furnace, combined with a Trane XR16 heat pump. Furnace is 3 years old, heat pump is 2. It took the installer quite a few trips to get settings straightened out, but units overall have been pretty good. I always seemed to have some noises after the oil heat shutdown, not the heat pump. It would be a constant 'ticking' sound while it was on purge and cooling down. When the techs came out, they thought it was the ductwork contracting, and as a solution they opened up all 3 zones once it goes to purge to I guess hasten the cooling. The noises did abate, but they did not disappear.

About 2 weeks ago, about 45-60 seconds after oil heat shuts down, I get a single bang, fairly loud. It is consistent after every oil heat shutdown. I get the same ticking sound, and then 45-60 seconds later, a single bang, and then more ticking. My service tech, different from my installer, was here this past Tuesday to do my annual cleaning. He's never heard that noise before and said it was not the ductwork and was clearly coming from inside the unit, and he feels it's something with the heat exchanger as it is a metal sound. Trane seems to have no technical support, my installer is coming back out next Monday to look at it again, but given their history I'm not confident they'll find what the issue is. The reason I got the new furnace is my old one had a massive hole in the exchanger and after coming back from vacation my entire house had a nice film of soot all over so I'm not looking forward to anything like that again!

Sorry for the long winded post but was hoping someone might have an idea as to what this might be or any suggestions to possible steps in troubleshooting. Thank you.

Jamie Hall

Very likely some piece of sheet metal (may be pretty heavy gauge) is contracting as it cools down. I'd be looking somewhere in the heat exchanger section of the unit. If there any fasteners, I'd look at them for security.

GeorgeM22

Jamie, thanks for the advice. I'll be sure to have them check that out.