What is a furnace filter? Why should I change it and how often? Let’s go over some of these questions in more detail.
What is a furnace filter?
A furnace filter is used to protect the inside components of your furnace from contaminants. Most often these are located at the return plenum right before the blower wheel. In some installations, filters may be installed at the air return louvers. Filters also serve as a way of cleaning the circulated air in your home. In fact, filters are classified by their MERV rating (Minimum Efficiency Reporting Value). The ratings with higher numbers trap the smallest particles. A filter with a MERV rating of 12 traps more particles than a filter with a rating of 7. Filters are generally made of a fiberglass or synthetic pleated material.
Why Should I Change My Filter?
The forced air system in your home operates in a cycle. The furnace blower wheel pushes heated or cooled air out through supply registers and returns air to the system through return registers. Returned air may carry animal hair, pollen, dust, dirt, etc. The components in the furnace will become dirty without a filter to provide protection. If the components get dirty the furnace will become less efficient and may lead to premature degradation of the system.
So why do we need to change the filter? If the filter gets dirty, it will continue to trap dirt and protect the furnace right? Well, if the furnace filter becomes too restricted it can cause some problems. The blower pulls air through the filter to circulate through your home. If the filter is too dirty your supply registers may have poor air flow. Think of breathing through a straw. With a dirty filter your furnace is operating in similar way.
In addition, your heat exchanger can become damaged. Heat exchangers are components that are heated by the burners in the furnace. The blower wheel pushes air past the heat exchanger to provide heat to your supply registers. If the blower wheel cannot push sufficient air past the heat exchanger then the heat exchanger may become too hot. Some safety devices generally exist in your furnace called high limit switches. Switches are designed to turn off the furnace when the heat exchanger temperature gets too hot. Nevertheless, heat exchangers can become damaged by excessive heat beyond the limits designated by the manufacturer.
How Often Should I Change My Filter?
The basic fiberglass filters should be changed every thirty days or you can follow the manufacturers recommendations. Most pleated synthetic filters like the one shown above, should be changed every ninety days or you can follow the manufacturers recommendations. These are only guidelines for filter maintenance. Filters need to be changed more often depending on pets, climate, and other living conditions. As a home inspector, the Lask Inspection Group, LLC of Rockford, Illinois often finds dirty furnace filters during an inspection. Basic maintenance like changing furnace filters can go a long way in protecting your home from expensive problems. A popular brand of furnace filters is the Honeywell brand. Various sizes exist so be sure to check the size of your filter prior to purchasing. Dirty filters are also important for commercial systems is well. Did you know we inspect commercial properties? We serve Rockford, IL and other Illinois cities such as Loves Park, Machesney Park, Chicago, Naperville, Aurora, Geneva, Dekalb, Sycamore, Elgin, Lake Zurich, Arlington Heights, Crystal Lake, and other Chicago suburbs.
