Ever wonder what that strange Noises coming from your gas or electric furnace could be?
Here is a collection of described noises that I have come across over my years in the field. They range from :
More often than you might think, some of these can be a simple fix if you can pinpoint the source of the noise.
The most active component in any furnace would be the Blower Fan Motor and a lot of these noises will be generated from this blower assembly. This is almost always located in the lower part of the furnace cabinet.
- The most frequently reported noise by far is Whistling. This is usually the result of a dirty air filter or the use of a high density (Merv) filter that chokes off the air flow. A dirty or frozen Air Conditioner coil (Evaporator) can generate the same noise.
- Worn bearings on an Electric Motor or Blower shaft will start off as a Squealing or Whining sound and over time turn into more of a Grinding or noise.
- If you have an older furnace with a belt driven blower, a misaligned, loose or worn fan belt can produce a Squealing, Tapping or Flapping noise.
- A blower unit that has not been mounted securely can develop a Squeaking or Rattling sound.
- A Rumbling sound is usually the result of a foreign object such as a loose piece of paper or filter media being sucked into the blower wheel causing it to be off balance. Have you replaced you filter lately?
Newer mid and high efficient furnaces with Draft Inducers carry with them even more opportunity for foreign noises to escape from your furnace. These sounds would be coming from the top half of the furnace cabinet.
- The Inducer motor itself over time will develop bearing wear and eventually create a Squealing, Whining sound, and in rare cases an unusual resonating type of Ringing or Howling that can most certainly drive you nuts.
- High efficient condensing Furnaces manage water collection through the Draft inducer (venter) and over time the collection tubing can get restricted with slime or sludge and cause your furnace to fail. Slushing, Gurgling, or any water type sounds are a good clue that maintenance is required.
The duct work that is connected to your furnace can also be a noise producing annoyance.
- Tinking, Flapping or Rattling type noises that are heard at your supply grilles can be the result of a loose damper or something foreign that is sitting in the air stream. (Children like to stuff things in registers when you’re not looking)
- . Does your new furnace sound different than your old one? If the furnace produces a Banging or Popping sound when the blower fan starts up, the ductwork may need to be re-sized or secured. New furnaces have higher volume blower fans that should to be speed adjusted to match the existing ductwork and safe operating limits for heat output.
Finally, here are furnace noises that should cause concern and immediate action since they can involve unsafe conditions with the use of Natural Gas. All of them can be compared to what you would hear or encounter with a gas Barbque.
- At the start of the heat cycle the gas valve is set to open and regulate the proper amount of gas at the right time. A Whooshing sound followed by a Banging or Rumbling noise is definitely not good.
- A Whistling or Howling noise coming from the burners is an indication of restriction in the gas train and should be serviced asap.
- Popping noises when the burners come on or shut off is also a dangerous condition.
If you smell gas or suspect a gas problem with your furnace, you should leave the space immediately and contact your utility supplier for further safety instructions.
Furnaces can work harder than your car and should be serviced annually.
Always use a gas certified service technician and remember to point out these strange noises.