It may seem like a minor detail, but cutting an air filter to make it smaller can have serious consequences. The size of the filter must be indicated in the instruction manual that comes with the air conditioning unit. Air filters come in a variety of sizes and it is essential that the filter is correctly sized to fit into an HVAC duct. If the filter is too small or too large, it won't properly seal the opening, allowing particles to pass through the system and reach the indoor air of the house or building.
It might seem like a simple solution to just fold or trim a filter that is too big for your system, but this is not recommended. Using an incorrectly sized air filter won't necessarily damage your air conditioning system immediately, but it will have an impact. This will reduce the efficiency of your heating and cooling system, which can add up quickly and become a noticeable problem on your next utility bill. Filters only work if air has to pass through them.
The filter has air resistance and a gap does not, so if you leave a 1-inch gap, a disproportionate amount of air will flow through the hole, making the situation even worse. If someone in a house has a cough, congestion, sneezing, or other cold-like symptoms, it's a good idea to check the quality of the air filter. Some air filters can lose their structural integrity and effectiveness if cut, especially if the person cutting them has no experience with air filters. In climates where air conditioning (AC) systems are only needed a few hours a day, the filter will last longer than in homes where the air conditioner works almost 24 hours a day. Depending on the type of air filter, it's recommended that most homeowners change their air filters every 30 to 90 days. Air filters that aren't changed often enough can become clogged with dirt, dust, or other particles. In addition to size, it is important to understand the nominal minimum efficiency value (MERV) of air filters.
If you moved to a new house or someone changed your air conditioner filters for you, you'll notice that whoever did the work put in the wrong size filter. Regardless of what type is best for your individual climate system, it's important that you change or clean your air filter regularly. As with any appliance, it's important to read and understand the manufacturer's instructions and guidelines before deciding to cut an air filter. As air passes through the fan of an air conditioning system, filters capture contaminants and particulates before the air passes through the ducts. In conclusion, cutting an air filter to make it smaller can sometimes compromise its structural integrity and effectiveness. It is essential that you use correctly sized filters for your HVAC system in order to ensure optimal performance and efficiency.
It is also important to understand the MERV rating of your filters and change them regularly in order to maintain good indoor air quality.