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MagiicAir
MagiicAir, HVAC Technician
Category: HVAC
Satisfied Customers: 110
Experience:  20+ years Commercial and Residential Systems
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I hear a loud bang when my furnace shuts off.

This answer was rated:

I hear a loud bang when my furnace shuts off.

MagiicAir :

this is likely due to a dirty heat exchanger backing up the gases in the chamber. To fix this, remove the vent pipe, then remove the top chamber cover and look inside there and see if rust hasnt covered the tops of the chamber exits. If so, then either take a vacuum cleaner and suck up that rust. Also look inside the lower burner chamber where the actual burners are and see if this is also covered with rust. Do the same thing there, vacuum it out or brush them out with a steel brush. This is not that difficult an operation and shouldnt take long to remedy

Customer :

Thanks, XXXXX XXXXX that.

Customer :

I wanted to print out the advice but it's gone. How do I get it back.

MagiicAir and 3 other HVAC Specialists are ready to help you
this is likely due to a dirty heat exchanger backing up the gases in the chamber. To fix this, remove the vent pipe, then remove the top chamber cover and look inside there and see if rust hasn't covered the tops of the chamber exits. If so, then either take a vacuum cleaner and suck up that rust. Also look inside the lower burner chamber where the actual burners are and see if this is also covered with rust. Do the same thing there, vacuum it out or brush them out with a steel brush. This is not that difficult an operation and shouldn't take long to remedy