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The Furnace Noises That Should not be Ignored

Furnace noises

HVAC systems have several moving parts and many of them rub against each other. Continuous operation, absence of maintenance, regular wear and tear and other factors can affect the performance of any machinery.

Your HVAC system comprises the cooling and heating units, air filter, return grills, air ducts and blower. All of them have the potential to cause or make noises indicating that something is wrong.

It is usual for older models of furnaces to make noise, such as humming when the blower is in operation or minor pops from the duct system. You have to be concerned when the furnace noises are quite loud, such as clamoring, rumbling or rattling from the air vents or walls. A qualified technician should check these types of furnace noises, as this could mean that the furnace needs maintenance, repair or replacement of some parts.

You should not ignore furnace noise that is out of the ordinary as this could lead to costlier repairs, or worse, some parts would have to be replaced.

Here are some unusual furnace noises that need immediate attention:

 

  1. Loud Metal-on-metal scraping sound

You have to turn off your furnace at once and call an HVAC technician if you hear a loud scraping noise. If it sounds like nail scraping a chalkboard or metal rubbing against metal, this means that the blower wheel of the furnace is out of order.

The following can cause the noises:

  • It was loosened from the motor shaft and scraping against the blower casing. The professional technician can just tighten the wheel if the shaft or wheel did not sustain major damage.
  • The blower wheel broke and must be replaced by a professional.
  • The motor mount broke and the entire blower assembly dropped, hitting the housing.

 

  1. Loud popping or banging sound when the furnace is turned on

There are two reasons why furnace noise such as loud popping or banging happens:

  • The air ducts are expanding and contracting. This is common for homes with metal ducts. When the furnace blower turns on and off, the ducts contracts and expands. It is a common problem when the air filter is clogged, the ducts are flimsy, the vents are closes or the ducts are undersized.

 

  • Furnace burners are dirty. When there is dirt buildup on the furnace burners, it can cause the igniting of the burners to be delayed, leading to gas buildup. When the gas finally ignites, there could be a loud bang. This is quite serious because although the explosions are small, they could cause the heat exchanger to crack. Repairing this part could be expensive.

 

  1. Whining or squealing noise

When you hear this kind of furnace noise, it could mean that the shaft bearings need oiling to lubricate them, which should be done by a professional technician. A fraying, slipping or loose blower belt could cause it. The belt, similar to a car’s fan belt, must be replaced if frayed or adjusted by an HVAC technician.

Why immediate attention is needed when the furnace makes noise?

Furnace Noises

A furnace is essential to keep homes warm when the weather turns cold. But it needs careful attention to maintain safety at home. A neglected furnace could leak dangerous carbon monoxide. Thus, you need to have your furnace properly and regularly maintained by a professional HVAC technician.

Aside from the major problem indicators mentioned above, other furnace noises:

  • A rumbling noise indicates that the heat exchanger is either corroded or dirty.
  • Huffing and puffing noise lets you know that that the burner or gas valve is corroded or faulty.
  • Scraping and grinding noises mean that the blower motor is failing. It could either indicate that the blower motor is past its life span and needs to be replaced. It could also mean that the absence of proper maintenance led to the motor’s failure to operate.

 

Fall is the time to have your furnace checked to avoid having a cold house in winter. Call Fischer Heating at 206-202-9499 or 425-406-3050 for preventive maintenance, even if you do not hear any unusual furnace noise. Our expert HVAC technicians can diagnose and troubleshoot any furnace issues.



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