Would it surprise you to learn that your furnace is equipped with its own air filter? If so, you may have a problem. The furnace air filter is a pretty hard part to spot, especially if you’re not really looking for it. This has led far too many homeowners to simply overlook the filter’s existence. Though the air filter may seem like a trivial part of your furnace, it happens to fill a vital role in the system’s operation. If not properly taken care of, the air filter can actually pose a very big problem to the furnace as a result.
Let’s take a look at what the air filter does for your furnace, and why you need to have it cleaned or replaced every few months.
What is the Furnace Air Filter?
The furnace air filter is a simple fiber mesh, stretched over a frame and installed in the air return duct leading to your furnace. It is there to protect your furnace from any debris that might otherwise get into the system and get it dirty, like dust. The air filter does this job well, capturing airborne particles that might harm the system while simultaneously allowing air to flow freely through it. The problem is that the air filter actually doesn’t have a way to get rid of the particles once it catches them. If not manually cleaned or replaced every 1-3 months, the filter can become clogged. This is where things start to get problematic.
Problems Caused by Dirty Air Filters
A clogged air filter significantly restricts the flow of air through it and into the furnace. This does two things. First, it cuts of the flow of air for the furnace to heat and distribute, leading to a drop in heating ability. Second, it traps all that heat inside the furnace itself. When the furnace has all of that heat trapped inside it, the internal temperature rises to dangerous levels and causes the system to overheat. A safety device called the “limit switch” will activate to shut down the system, but will not be able to actually fix the source of the overheating. If the air filter is not cleaned, the furnace will become locked in an endless cycle of starting up, overheating, and being shut down by the limit switch. This is called “short-cycling” and is extremely damaging to the furnace.