In todays world with work, school, taking care of the kids, and life in general, it's easy to forget replacing that $5 air filter in your HVAC system. What many homeowners don't realize is that $5 filter can become an obstruction, and a problem, similar to a clogged artery. Your air filter is designed to trap dirt and particulates which you could breathe, it's primary function is to keep those particles from becoming trapped in your evaporator coil. The air that flows through your system transfers heat to either heat or cool your home. Your system is engineered to operate with a calculated amount of airflow. When your air filter becomes dirty, it restricts the air coming into your furnace or air handler. This can cause a wide range of problems from overheating furnaces, to frozen evaporator coils and even blown compressors (the valves in the compressor can actually become damaged). It also diminishes your systems efficiency and wastes energy.
During my first summer as an HVAC tech, we arrived to an AC problem call. The customer complained that his system was not providing sufficient cooling. The system was putting out the appropriate discharge temperature. So we went on to check the next thing, the air filter. When we pulled out the filter from the track, we could audibly hear the system began to breathe. No faster than we could check the filter, a growing whistling noise caught our attention. Just like the sound of a hot water kettle, we traced it outside to a brand new AC condenser unit. We immediately knew something was wrong, so I shut down the unit. Some genius tech before us got a low pressure reading so they decided to charge the system with additional refrigerant (about 2 pounds more). All they needed to do was replace the filter.
This was the most dramatic case I ever saw (I never ran into a situation like that again).
But this occurrence showed me how important airflow is to an HVAC system. Dirty filters can cause frozen evaporator coils in AC and heat pump systems. As the refrigerant passes through the frozen coil, it is unable to capture heat from the lack of air moving past it. The refrigerant fails to evaporate properly, and returns to the compressor as liquid. Since liquids are not compressible, the compressor becomes damaged and, over time, fails. The water from the melted ice is also a culprit in drywall damage in attic units, where the water overflows and only becomes apparent to the homeowner when they see the water dripping through the ceiling.
Furnaces are affected differently. The lack of airflow causes the furnace to overheat, triggering a safety mechanism which causes it to shut off. However, when this is chronically repeated, the heat exchanger overheats and cools more frequently. Over the years, this can cause cracks in the heat exchanger which can actually become a safety hazard.
Although life keeps us busy, there are some things you can do to remind yourself to change your filter. With the wide use of smartphones, homeowners can set reminders on a monthly basis to check, and if necessary, replace their filters. In addition, you can purchase "value packs" at your local home improvement store. This can save you the monthly trip of shopping for a filter, as well as some "$$$". Another solution which might not come to mind right away is smart thermostats. Smart thermostats are becoming more common. The can help you save energy, and money. They also provide added control and convenience. But they also offer service reminders for such things as air filters. they can even contact your chosen HVAC Service Provider via email to alert them when your system is having issues. What fewer customers are aware of is that Energy Star certified thermostats are becoming eligible for rebates from your energy company, up to $100! There are also high efficiency filters which can be changed at longer intervals; up to a year. HVAC companies even offer services to deliver filters to your door on a predetermined basis.
Dirty air filters can lead to some serious issues with your HVAC system. However, with an established plan, you can easily and economically address the simplest troubleshoot of any HVAC system, maximize the life and efficiency of your equipment, and save yourself a service call.