What's the cause of that rattling noise in my furnace?

July 22, 2014

Furnaces tend to make some strange sounds leaving you to wonder what's normal and what isn't. Here's some advice to help you know the difference.

What's the cause of that rattling noise in my furnace?

Forced-air systems

  • Forced air furnaces are highly efficient heating systems that quickly and evenly warm up a house.
  • They also double as a central air conditioner in the summer and add value to any home.
  • On the other hand, these systems have many composite parts: motor, fan, humidifier, pipes, filter, attachments and more – potentially a source of noise that will carry throughout the house as heat travels up through the registers.
  • As such, the more you know about forced-air systems, the better.

Common noises

One of the most common noises people complain about when it comes to their furnace is the sound of a boom or rattling.

  • This usually occurs when you start or turn off the furnace, or shortly thereafter.
  • If this is the case, the sound is likely normal and it’s just the effect of the metal ductwork expanding and contracting with the increasing or decreasing temperature.

If the furnace is kept in an unheated basement, and it’s especially cold, the heating element may cause a thermal shock as it warms up and starts to force warm air through the system.

  • Under these circumstances, noises can be expected.
  • If, however, the noise becomes louder and becomes non-stop, your system may be in need of some tweaking.

What to investigate if you hear a noise

Your heating system is bound to make some operating sounds, so there’s no need to worry about every single noise you hear. Things to check include:

If you're unsure where to begin, a good place to start is by troubleshooting using the manufacturer’s instruction manual.

  • If necessary, contact the supplier. They will be able to dispatch a technician and check for problems.

How to maintain your furnace

The life span of a furnace is about 15 years, so to guarantee optimum performance remember to follow-up with regular maintenance. This includes cleaning the air furnace filters regularly during periods of use.

  • Although you can likely troubleshoot most of the simpler issues yourself, an annual inspection by a qualified and certified technician is highly recommended.
  • It's a good idea to fix small problems with your furnace before they grow into larger, and more costly, repairs later on.

Remember that comfort and safety come first: be sure to maintain your system just as you would your car or your home. You’ll prolong the life of your furnace and enjoy years of worry-free heating and cooling.

The material on this website is provided for entertainment, informational and educational purposes only and should never act as a substitute to the advice of an applicable professional. Use of this website is subject to our terms of use and privacy policy.
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