Dangers of Not Replacing the Air Filter

air-filterThe air filter is one of the simplest, least-technical parts of your entire heating system. Yet, it can be the one that causes the most problems. It’s often the simplest functions that can be the most important, after all.

Whether you’re using a furnace or a heat pump, you can expect to find an air filter in any forced-air heating system. Their purpose is to prevent dust and dirt from damaging sensitive components inside the machine, and they’ll need to be switched out every few months. Here’s what can happen if you wait too long to replace it.


While a clogged air filter in an air conditioner is nothing to scoff at either, heaters come with the danger of overheating. When things get too hot, it can cause the heater to malfunction, or it might even start a fire (luckily, there are many modern-day fail-safes to help prevent this).

Furnaces require a steady stream of oxygen to combust gas and to move heat through the system. A clogged air filter can be enough to slow that down, resulting in too much hot air lingering in the furnace. A limit switch is in place to turn off the furnace in such an event, so if your furnace seems to resist staying on, check the air filter. If that doesn’t work, try calling in for furnace repair in Portland, OR.

Flame Rollout

Oxygen is required for the furnace to combust natural gas into heated air. A clogged air filter can prevent enough oxygen getting through, and that can result in “flame rollout.” It’s about as scary as it sounds, as flames will “roll out” from the furnace cabinet to suck up more oxygen. Running the furnace in this state can be dangerous, as it might catch fire to nearby objects.

Frozen Coils

Heat pumps operate thanks to refrigerant flowing back and forth between two sets of coils. The phase changes that take place between these coils is what helps the heat pump remove warm air from your home in summer and bring warm air in during winter. A clogged air filter can cause the evaporator coil to become too cold, resulting in ice and frost. This can cause the heat pump to stop functioning, and it might even be enough to damage its compressor.

Short Cycling

Whether you’re using a furnace or a heat pump, another big threat of a dirty air filter is short cycling. Now, all heaters are going to go through heating cycles—the difference is when those cycles occur rapidly and within minutes.

A common cause of short cycling can be from a heater that is too powerful for the home. Typically, that means having to get it replaced. So before you let anyone talk you into installing a brand new heater, check the air filter and try running it again—it just might be what you need to fix the problem.

If your heating is acting strange but changing the air filter hasn’t helped, it’s time to contact The Clean Air Act to schedule a service.

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