Does your gas furnace make more noise than it used to? Does it make a squealing sound or have a low pitched rumble sound?
The high pitched squealing sound could be caused by the belt of the blower slipping. The first thing to check for is proper belt tension. The belt should depress about 1″ at the center of span. If the belt is too loose it should be tightened but a belt that is too tight can damage your furnace. We suggest calling a heating contractor unless you feel confident about tightening the belt. If you notice the belt is frayed on the edges, this could also be causing the noise. The belt will need to be replaced.
The squealing sound coming from the gas furnace could also be caused by the motor or shaft bearings in need of oil. You will want to oil blower motor lubrication ports, which are usually at each end of the shaft, with a light weight oil.
Is the gas furnace is making a low pitched “rumble” sound? This may be caused by a poorly adjusted pilot light if the problem is occurring with the burners off. If conversely the problem occurs with the burners on it may be caused by dirty gas burners. To repair these issues you will need to adjust the pilot light or have the burners cleaned or adjusted. We recommend you call a professional heating technician for either of these heating repair issues.