Having an HVAC system requires constant maintenance because if left unattended it will require the replacement of the whole system. Remember that HVAC stands for heating, ventilation, and air conditioning. There are different systems used to move air between indoor and outdoor areas in conjunction with the heating and cooling of residential and commercial buildings. They keep the environment warm and cozy in winter and cool and temperate in summer. This type of system filters cleans indoor air to keep it healthy and with low humidity levels.

What is an air filter and how does it work?

Replace furnace filter

Air filters consist of spun fiberglass or pleated paper and a frame with cardboard for rigidity. They go inside the return air duct.

These air filters act as barriers to block dust, dirt, pet hair, lint, mold, mildew, bacteria, and other elements. Air filters usually have a MERV (minimum efficiency value) that determines the type and size of contaminants the filter works against.

What is MERV?

It is an index that measures how effectively a filter prevents dust and other contaminants from passing through the filter and directly into the air stream. A high MERV rating retains very small particles, including microorganisms and dust particles. In other words, they are better and more efficient than those with lower MERV ratings.

In general, filters with a MERV rating of 16 or lower are considered HVAC-grade filters for residential, commercial, and general hospital use. MERV 17 to MERV 20 filters are typically used in operating rooms, clean rooms, and other environments that require absolute cleanliness.

How often should you change the filter of your HVAC?

Generally, most air filter manufacturers and HVAC companies recommend changing your air filter every 90 days, or 3 months. This can change based on where your home is located (ex. dusty, dry climates) if you have any pets, and the age of your system and equipment.

We advise changing your filter every 20 to 45 days for homes with lots of dogs, as well as for people who have allergies or respiratory conditions. Consider doing it every 60-90 days, or every two months, if you have pets. In holiday houses that are infrequently used or abandoned, you may typically wait nine to twelve months before changing the filters. The more you use your home, the more frequently you should change your air filter, according to common wisdom.

What Happens if you don’t replace your HVAC filter?

Hvac inspection and maintenance

It is normal to confuse the real use of an air filter. These are mostly used to protect the components of an HVAC system, of course, some of them filter small dust particles but it is not their main function.

Over time these filters fill with dirt and dust, depending on the type of system, which will determine how often it will have to be cleaned more or less frequently than others. Paper filters are disposable, in any of their versions, with cardboard frames, paper mesh, etc. On the other hand, reusable filters with metal frames can be easily cleaned and have a longer useful life.

Dust and dirt

Dust and dirt accumulating in the air vents may be due to a clogged filter. This causes dust and dirt on surfaces in the house as they pass all of these particles directly into the ductwork. Another sign of dust and dirt is worsening allergies. Immediately replacing the filter will reduce the dirt and dust expelled by the system by almost 90%.

The filter looks dirty or clogged

There is always a visual factor in deciding to change the filter of an HVAC system. When it is full of dust, looks clogged, or is broken or damaged, it should be replaced immediately. This can lead to major problems, such as straining the motor, decreasing air quality, restricting airflow, being forced to provide a given temperature, and causing problems or collapse.

Increase in your electric bill

Suddenly you see a substantial increase in your electricity bill, it may be that your HVAC system is damaged and is consuming more electricity than it needs. This is to maintain a temperature that you are having trouble reaching. This problem may be caused by the filter.

It takes longer to heat or cool your home.

If you notice that your HVAC system does not reach the given temperature or slows down, the filter may be clogged or damaged. A dirty filter limits the amount of air that can circulate through an HVAC system.


If the system struggles to work and overheats or is hot to the touch or even air blows out the back. Increased wear and tear and overheating can lead to repairs and complete air failures.

The next effects to worry about are the other contaminants that enter a dirty system. The only type of filters that trap allergens and spores are HEPA or high-energy particulate air filters. These are made of a much finer mesh than other filters, so they can filter out tiny particles such as allergens, pollen, dander, and mold spores.

Read more: HVAC inspection

How much does it cost to change the filter in your HVAC?

A filter for an HVAC system can cost about $40, depending on the model. It’s nothing compared to buying a new one or fixing a motor, for example. But it is vital to its proper functioning and health, plus changing it will only take a couple of minutes.

The more advanced the filter technology, the higher the price level. By evaluating price variations, you can be sure to buy an air filtration system that can fit your budget. Below are some estimated costs, although they really vary depending on the application.

  • Flat and pleated filters: $12 – $62 each
  • HEPA filters: $2400 to $3000 each including installation.
  • Extended filters: $500 to $1000, including installation.
  • Electronic filters: $700 to $1,200, including installation
  • Ultraviolet light add-on: $800 – $1,200

Flat filter systems may be the most economical in the short term but become a long-term rental. For this reason, many prefer to go for much more advanced systems that may consume less electricity, have a more complete filtration system, and are low maintenance.

How to change your HVAC filter

hvac plenum

The first thing is to look for the instruction manual, if you don’t have it you can look it up on the internet, it will tell you what type of filter you need to buy and how to install it. But here are some useful steps:

Step 1: Turn off the system

Disconnect power to avoid further problems.

Step 2: Locate the filter

Here you will use the manual to locate it.

Air conditioning filters are usually located in several places. It may be under the return air register grille on the wall if the HVAC system is in the air handler cabinet.

If you have an up-flow or horizontal system in the basement or attic, you most likely have a small 1″ filter. You can usually find this filter under the removable door outside the furnace, between the furnace wall and the air distribution box (also known as the plenum).

Step 3: Remove the screws

To get to the filter, you will need to remove the screws that hold the lid and filter respectively. At this point my recommendation, from experience is to take pictures with your phone or draw on a piece of paper and tape the position of the screws, so you know where each one is located. If the filter has a cover, start by removing and cleaning it before changing the filter.

Step 4: Remove the dirty filter.

Have the floor lined with paper or newspaper to avoid spreading dust, a large garbage bag for disposal, shake it out, or wash it outside the house.

Step 5: Check the arrows on the new filter

Make sure it is installed correctly. There are usually guides provided to put the filter correctly. Turn on the appliance before closing it completely to verify that everything is in order. If everything is OK, write on a piece of paper or on a strip of paper the date of change so that you can keep track of the time it has been in operation, or keep track with an amazing maintenance schedule app.

Now, close everything completely, clean and put it back to work.

Replacing an HVAC filter is a simple, easy process that will not take time and will extend the life of your system, without having to go through complicated repairs or replacement with new models.

HVAC filter replacement: What to consider was last modified: June 28th, 2023 by Vanessa Gallanti
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