Both oil and electric furnaces can make a number of alarming or annoying noises during operation. Some noises are harmless and are a byproduct of mechanical or electric parts while others indicate serious problems. New noises should be checked by a service professional to ensure your furnace operates safely and efficiently.
Inducer Motor or Fan
Some oil-burning furnaces feature inducer blowers, which are motor-powered fans that blow the smoke and other byproducts of the combustion process into the flue for safe venting. Both the motors and fans on these parts can cause loud clicking or chirping noises, says the Homeowners Hub. Bearings in the inducer blower will make clicking noises that are most noticeable when the burner itself shuts down but the inducer continues to blow. A high amount of dirt and soot building up around the fan shaft can also cause it to click while spinning. Inducer blowers are usually covered by a squirrel cage frame to protect them. If this cage comes loose, it can click by bumping into other components due to the vibration of the furnace.
Motor Bearings or Shaft
The bearings located in the main blower motor of the furnace can also make clicking noises as they wear out, according to the Ductwork Installation website. Worn bearings can cause the motor to burn out, so a clicking noise from the blower motor is a sign to have your furnace professionally serviced. Blower fans in your furnace rotate on a main shaft that attaches to the motor, and, when this shaft becomes rusted or clogged with debris, it can also click while operating. Lubricating and cleaning the blower fan shaft regularly will prevent this.
Most furnace pilot assemblies will not make any noise when trying to ignite fuel oil or gas, but some rare models do. These pilot assemblies can become bent slightly and fail to produce ignition because they are too far from the oil or gas spray, says G&S Mechanical Services. Bimetal pilot assemblies, mainly used in Carrier brand furnaces, often stop working and begin producing a noticeable clicking noise when they become dirty or worn. Pilot assemblies and insulators in other furnaces can be cleaned with solvents or sandpaper, but these special bimetal pilot assemblies usually require replacement.
Random and nonrhythmic clicking coming from the gas valve may indicate that it is not receiving a sufficient voltage to operate properly, according to Ductwork Installation. Malfunctions in the gas meter controls or the thermostat controls can trigger this random operation. Your furnace may also work intermittently or only become fully lit for a few minutes at a time due to the stuttering flow of gas. Testing the voltage at the gas meter, the thermostat controls and the gas valve itself will help determine which part is causing the problem. All three can be replaced, but the gas meter controls are usually replaced only by the gas company.