How to Find the Right HVAC Filter Size

An HVAC system is one of the biggest investments you’ll make in your home. You can protect it with regular maintenance, such as changing the air filter. Maintenance should be performed by a qualified HVAC technician but changing the air filter is one thing you can do for yourself.

Air filters take a lot of stress over time and wear out as they work to filter out the contaminants in your home. If you think your air filter is in need of replacing, you can do it yourself if you know the right filter size and type. Of course, you can always contact an HVAC technician.

Why Does the Air Filter Size Matter?

The air filter size is one of the most important aspects of replacing the air filter. Having the right size is important for the health, efficiency, and function of your HVAC system. If you get an air filter that’s too big, it won’t fit in the designated slot. You can’t just cut it down to the right size, since this will leave gaps where pollutants can enter your home.

Similarly, you can’t get by with a filter that’s too small. This also leaves gaps that allow contaminants in and compromises your air quality. Always get the right size air filter.

Look at Your Existing Air Filter

The simplest way to get your air filter is size is with your current air filter. Most filters have the size listed on the edge in small print, including the length, width, and depth. The units may not be there, but they’re measured in inches.

An example of a common air filter size is 18x30x1. This indicates a filter that’s 18 inches long, 30 inches wide, and one inch in depth. You can find air filters in standardized sizes, so it should be easy to find the right replacement size.

Measure It Yourself

Some filters don’t have a size listed on the edge. If you can’t find the size easily, you can measure it yourself and do some calculations to get your filter size.

The dimensions you measure will be slightly smaller than the actual size of the filter you need. Using the previous example, a filter that’s 18x30x1 may measure as 17.5 inches by 29.5 inches by .5 inches. Round these numbers up to the nearest inch, paying attention to orientation, and find the appropriate filter size.

Measure Air Register or Air Filter Slot

If you don’t have an air filter or otherwise can’t get the size from the filter itself, you can measure the slot it goes into to get the size. You will need to do some calculations for this as well.

Generally, the slot will be the measurements for the air filter itself, not the actual size of the replacement. You will need to round up to the nearest inch again to determine the air filter size to look for.

Where Is the Air Filter Located?

HVAC air filters are usually found on the return air intake. This is located near the return where the intake comes into the HVAC system. There’s usually a plate that covers the slot.

Most HVAC systems won’t have an air filter on the air handling unit. If this is the case, you can find the air filter on the return vent where it comes into your house. If you can get to that area safely, you will be able to change the air filter yourself without the help of a professional.

Know Your Air Filter’s MERV Rating

Once you know the size of your air filter, you also need to determine the MERV rating. Air filters use a MERV rating to measure their ability to filter out small particles in the air and preserve your air quality. The higher the MERV rating, the better the filter does at removing contaminants.

It’s not good to just choose a higher rating for the sake of it, however. Higher MERV ratings will filter out more contaminants, but it comes at a cost to efficiency. These filters are thicker than lower rated filters, which means your system needs to work harder to circulate air in your home. This increases your energy bills.

Most homes will do well with a MERV rating of 5 to 8. This is enough to capture main contaminants like dust, pollen, mold spores, and dander. You won’t experience a loss of efficiency, either.

If you have someone in your home with respiratory conditions like allergies or asthma, then you may need a MERV rating of 10 or 12 to get cleaner air. These ratings are better for capturing allergen particles down to one micron. You will pay more for energy bills, however, so keep this in mind.

Do you need regular HVAC maintenance or repairs, contact Moore Home Services to schedule your consultation!