Furnaces are noisy systems, as you probably well know. If you’ve had your furnace for any length of time, though, you probably already know which furnace noises are normal and which are not. If your furnace is making some unusual noises during operation, it’s likely that there’s a problem with the system. Let’s take a look at some of the more common furnace noises that indicate a repair issue.
The furnace circulates air throughout the house using a part called the air handler. The air handler is put under a lot of stress during operation, so it’s equipped with oiled bearings that help to reduce friction on the motor. As the bearings wear down over time, the friction on the system increases and produces a loud grinding sound. If you hear grinding coming from your furnace, you should shut it down and call for repairs right away. If the bearings aren’t replaced, the air handler motor can burn out.
If your furnace is turning on and off every couple of minutes, it’s short cycling. Short cycling is a behavior caused by heat becoming trapped in the furnace, often due to a clogged air filter. This causes the furnace to overheat, which activates the limit switch and shuts the system down. This is only a temporary measure, though. If the source of the overheating isn’t fixed, the furnace will simply start up again and shut down again indefinitely. Short cycling puts the furnace under an immense amount of stress. If the problem isn’t fixed, the furnace will eventually break down under the strain. Call for repairs as soon as you notice your furnace turning itself on and off rapidly.