The Impact of Dirty Filters on Air Flow

If you have a dirty or clogged air filter in your HVAC system it can cause low airflow and make it work harder than necessary. Learn how this affects energy bills & indoor air quality.

The Impact of Dirty Filters on Air Flow

If you have a dirty air filter, it can cause low airflow and make your HVAC system work harder. Not only does it restrict airflow, but it also reduces the efficiency of the entire system. A clean air filter will not prevent airflow in and out of your unit, but a dirty one will. This can cause cold air to build up inside the air conditioning unit and lower the temperature.

When the air filter becomes clogged during the summer cooling season, cold air buildup can cause ice to form on the air conditioning coils or evaporator. This freezing will reduce the HVAC system's ability to remove heat from the air and eventually cause the air conditioner to fail. Central air conditioning relies on continuous air recirculation, and when that airflow is hampered by a dirty or clogged air filter, it means that your system has to work a lot harder to cool your home. The harder the system has to work to extract air throughout your home, the more energy you need and the higher your energy bills will be.

This inefficiency intensifies as the filter becomes more and more clogged. In other words, every time your system is forced to work harder, it's costing you dearly (PLUS, you get less air for the money). Dust and debris in a household air cleaner also restrict airflow, forcing your oven to strain and use more energy to heat or cool your home. Like replacing your car's engine oil and air filter every 3,000 miles, a clean HVAC air filter protects your heating system from damage and ultimately complete failure.

Yes, pleated air filters do restrict airflow to your HVAC system, but all filters will restrict airflow to some extent. What you want to worry about is finding the right filter for your unit and your overall system to ensure that you reduce the amount of contaminants in the air as much as possible. In general, a filter with a higher MERV rating will reduce airflow. However, there are many other factors at play, such as the size of the filter and the type of fan motor in your HVAC system.

A clogged or dirty air filter can spread contaminants such as dust, dirt, pollen, and pet dander instead of trapping them. It can also restrict the airflow of your system, forcing you to work harder and consume more energy. Clogged air filters can make ducts dirty and leave a lot of extra dust throughout the house. Also be careful with dirt on the fan blades.

A dirty filter won't be able to protect your HVAC system. Now, many people will hear that pleated air filters cause airflow restriction, and they automatically think this is a bad thing, so filters are not suitable for what they are looking for. We recommend at least checking your air filter once a month, but advanced filters can last a little longer. However, considering the reduction in airflow caused by a high MERV filter is often an afterthought for most homeowners. The type of blower you have in your oven or air conditioner will largely determine if there will be a reduction in airflow in the system. Pleated air filters are great and are incredibly common air solution options; you just need to know which one is right for you.

In fact, even filters with high MERV ratings can be used in some systems with minimal pressure drop. When you're considering what type of air filter to install in your home, make sure you research and know what you're really looking for; otherwise you could end up buying one that will cause more problems in the future. This inefficiency increases rapidly as the filter becomes more and more clogged or until it is serviced. According to the Diamond Certified Organization, a clogged oven air filter is the main cause of equipment failure. A dirty air filter will cause poor indoor air quality and can cause allergens to build up in the system, leading to respiratory problems or even mold in the ducts. A dirty air conditioning filter can wreak havoc on your HVAC system and lead to costly repairs or a complete breakdown when you need your air conditioner most. If you have pets or have a lot of chemicals in your house, indoor air quality will be even worse with a clogged filter.