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The Furnace Filter: If Left in Place, Your Furnace May Malfunction!

Furnace Filter

One of the big jobs I take on as an HVAC blogger dog is to fight the misinformation and misconceptions out there about residential heating and cooling. I know I’m only one dog in a big world of the internet, but I think I can make an impact in helping people with the best info so they get the performance they deserve from their HVAC equipment.

And that’s why it’s once again time for me to talk about the furnace filter. The lowdown: You need to change the furnace filter yourself during the coming months at regular intervals, or it will cause trouble for the furnace!

A Clogged Furnace Filter Does More Than Make a Furnace More Expensive to Run!

If you follow my blog, you may have come across my advice about how a clean air filter in the HVAC system is essential for keeping it working at high efficiency. When the filter is clogged, the blower fan for the furnace must work harder to draw air through the system. It’s not much different than how it’s more difficult for someone with a bad cold to breathe: too much congestion. You don’t want your furnace to waste power dealing with a clogged-up air passage the whole winter. 

But the dirty furnace filter can do worse than raise the cost to run a furnace. It can cause the furnace to malfunction, including a possible breakdown, that will require you to call us for furnace repair in Knoxville, TN. Of course, we’re always glad to come help you—it’s why we’re here!—but we know you’d rather have a working furnace that doesn’t need repairs.

What Can Go Wrong With a Furnace That Has a Clogged Filter

Several things! I’ll list the most common for you:

  • Overloaded blower fan trips breaker: The extra strain on the blower fan can easily cause the fan to overheat and trip the circuit breaker to the furnace, shutting it down. (Yes, gas furnaces as well. A gas furnace has an electrically powered control board that will shut the system down if there’s no electricity.) I always caution people when a circuit breaker trips because of the HVAC system to always check on the filter to see if it’s clogged. 
  • Furnace overheats: A clogged filter will cause more heat to be trapped inside the furnace, which can lead to the limit switch getting tripped and the furnace cycling down. You may have a furnace that is constantly short-cycling, which puts immense strain on it, or one that just won’t stay on at all. 
  • Broken blower fan motor: The blower fan motor may overheat and burn out because of the stress placed on it. This is often the result of short-cycling that keeps the system turning on and off again repeatedly. Replacing a blower fan motor is often expensive.
  • Damage from dirt in the furnace: When the filter is clogged, it will begin to allow dust and dirt and other debris to get around the sides. This contamination inside the furnace can do immense damage to motors, moving parts, block the burners, and more.

So please change the furnace filter regularly … starting now with a fresh filter for the coming winter! We recommend filter changes every one to three months depending on the strength of the filter.

Stay warm,