Can You Use an Air Filter That's Too Big?

When it comes to air filters, size matters. Learn why it's important to check your existing filter before purchasing a replacement one and why folding or trimming an oversized one is not recommended.

Can You Use an Air Filter That's Too Big?

When it comes to air filters, size matters. It's important to check the size of your existing filter before purchasing a replacement one. If you buy a filter that is too large, it won't slide properly into the slot. If the filter is too small, it won't cover the entire space and may allow dust and dirt to pass through.

It may seem like an easy solution to just fold or trim a filter that is too big for your system, but this is not recommended. Folding the filter makes the seal imperfect, allowing air to bypass the filter and accumulate dirt and debris on the fan. This slows down airflow, degrades performance, lowers air quality, and creates a mess that will need to be fixed or cleaned later. The filters of the oven must fit securely, but must not be forced into position. If you have to force the filter into its slot, it's probably too big.

Forcing an incorrect filter size on a filter can cause it to bend, damage the filter, or reduce its ability to function properly. The filters are smaller than their slot to allow easy replacement. In some cases, you may need to order a custom filter. 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 gap of 1, a disproportionate amount of air will flow through the hole, which will further worsen the situation. If you have sensitive lungs or are asthmatic, you may want to consider a filter in this range, although it will reduce the efficiency of your HVAC system.

However, the larger surface area of pleated filters allows them to capture more particles than their non-pleated counterparts. Before wasting time with the HVAC unit manipulator or return air central ventilation, first adjust the thermostat to turn off the air conditioning system. Another important function of these HVAC filters is to protect the HVAC system from intrusive particles that could damage it. If the filter does not have actual dimensions on the outside of the filter, you can measure the filter to get the correct dimensions. However, they usually add an additional surcharge to the filter to compensate for the services they provide.

A deeper depth can also improve filter life and efficiency; they also make it easier for air to enter and exit the filter. Not understanding these numbers often leads consumers to buy a filter that doesn't fit their oven or HVAC system. The entire filter may collapse while installed, which creates not only a performance problem and potentially costly repair, but can also create unsafe conditions. You can find the recommended filter size for your unit model in our table titled “Find your air conditioner and oven filter by make, model number and size”.