Is your gas furnace making a loud noise, at least louder than it used to be? If it makes a squealing sound or a low pitched rumble sound we may know the source of the problem?
The high pitched squealing sound is usually the blower belt slipping. The first thing to check is proper belt tension in the belt. The belt should depress about 1″ at the center of span. If the belt is too loose it should be tightened, but be careful not to tighten the belt to tight. 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. In this case, the belt will need to be removed and replaced.
The high pitched squealing sound could also be caused by the motor or shaft bearings in need of oil. To take care of this, oil blower motor lubrication ports, which are usually at each end of the shaft, with a little light weight oil.
A low pitched “rumble” sound coming from your furnace may be caused by a poorly adjusted pilot light (if the problem is occurring with the burners off). If the problem occurs with the burners on it may be caused by dirty gas burners. The possible repair for these issues is to adjust the pilot light or have the burners cleaned and adjusted.
We recommend you call a heating contractor for either of these heating repair issues.