Are Your HVAC Filters Costing You Money? Here's How Often You Should Change Them

Published onJuly 6, 2024
Appliance Maintenance and Care

Your home’s HVAC system works tirelessly to keep you comfortable, but it needs your help to operate efficiently. One of the most important things you can do is replace the air filter regularly. But when should you be changing them?

Many homeowners struggle with this and either change their filters too frequently or not enough.

Changing them too often wastes money, but not changing them enough can lead to poor indoor air quality and cause problems with your HVAC system.

So when should you really be changing your air filters? And is there a way to tell if they need to be replaced?

We’ll cover all that and more below.

Table of Contents

How Frequently Should HVAC Filters Be Changed and How Long Do They Last?

Most HVAC companies and technicians will tell you it’s a good idea to replace your HVAC filter every 90 days (3 months). However, this won’t be the case for every home. The actual lifespan of an air filter heavily depends on:

The type of filter being used
How often the HVAC system runs
The number of people and pets who live in the home
The size of the home
Outdoor and indoor air quality

Filter Type

Flat Fiberglass Filters

Fiberglass filters are low-cost options that typically need to be replaced every 30 days or less.

Their flat design limits the surface area where dust and particles can be collected so they’ll need to be replaced more frequently than other types of filters.

Pleated Filters

Pleated filters can last 3 to 12 months, depending on how thick they are. They’re able to last longer than flat filters because they have an accordion-like design, which has folds that create a larger surface area to trap more airborne particles.

The thickness of the filter will also affect how long it can last:

1” to 3” pleated filters last up to 3 to 6 months.
4” to 5” pleated filters last up to 6 to 12 months.

Reusable Electrostatic and Washable Filters

These filters can be reused multiple times if cleaned and dried properly every 1 to 3 months. While they need regular cleaning and reinstallation, the filter itself can last for an extended period.

Depending on usage and maintenance, they will need to be completely replaced (thrown away and a new one purchased) every 3 to 5 years.

How Often The HVAC System Runs

During colder winters and hotter summers, your HVAC system will work harder and run more consistently to help maintain your desired indoor temperature. The more air passing through your system, the more the filter will collect.

For vacation homes or places where temperatures are milder, there might not be a huge difference in outside and indoor temperatures, so you might not have to change the air filter as often.

However, it’s still important to check these, as outdoor particles can still be brought into the home through small openings and cracks and accumulate even if the system isn’t in constant use.

People and Pets Who Live in the House

The more people and pets in the home, the more dust, hair, and dander floating around.

Larger families, especially with young kids who tend to bring in more dirt and dust, may find their air filters getting dirty sooner than in a home with just one or two adults.

Similarly, if you have pets who shed a lot, their fur and dander can fill a filter faster, adding to all the other particles your HVAC filter already collects.

People with allergies or respiratory conditions may benefit from more frequent filter changes to maintain optimal indoor air quality.

House Size

Larger homes need more airflow to maintain consistent temperatures throughout each room.

This means the HVAC system has to work harder and filter more air compared to a smaller home to achieve the same amount of temperature change.

Because more air is being used in larger homes, the air filters will need to be replaced sooner than in smaller homes.

Indoor and Outdoor Air Quality

The quality of the air, both inside and outside your home, affects how quickly your HVAC filter becomes dirty.

For example, if you live in an area with poor outdoor air quality or a place that’s prone to wildfires, you’ll probably need to change your filter more often.

Indoor activities that generate airborne particles can also impact how long your filter will last.

These include things like:

Cooking

If you cook a lot, especially when frying — a lot of grease, smoke, and steam gets into the air. These byproducts can quickly accumulate and be captured by your HVAC filter.

Cleaning

Vacuuming, dusting, and sweeping stir up a lot of dust and dirt that settle on surfaces. Eventually, these particles are drawn into your HVAC air intake.

Even though the whole point of cleaning is to try and remove these particles, they’ll collect in the system’s filter quicker if you clean often.

Smoke

Smoke from tobacco, fireplaces, and candles releases soot and ash. These particles can easily clog up your HVAC filter, making it less effective at keeping your indoor air clean.

Construction or Renovation Projects

Cutting wood, sanding walls, tearing down cabinets, etc., creates a noticeable mess. But they also create small particles you can’t see.

These particles are finer than normal household dust and spread easily through the air. They penetrate deeper into the filter material and clog smaller pores in the filter faster.

Most contractors will try to keep them out of your HVAC system, but they could still clog up your filter fairly quickly, especially if there’s outdoor air coming in from opened windows or doors during the project.

How Do You Know When Your HVAC Air Filter Needs to Be Replaced?

Here are a few ways you can tell your HVAC filter needs to be replaced without having to call in an expert.

Visual Inspection

Clean filters are typically white or off-white, so a noticeable buildup of dirt is a clear sign that they need to be replaced.

Even if they look ok at first, you might need to remove them and take a closer look.

This is simple and doesn’t require any tools to do it. Here’s a simple guide:

How to Visually Check Your House HVAC Air Filter

Locate your filter: Filters are located at each return air duct for your HVAC system. They’re covered with a louvered grill. If you use a gas furnace, you’ll also have an air filter in the blower compartment that you’ll want to check.
Remove the filter: Start by opening the louvered grill holding the filter in place. Most will have latches that you push to the left to unlock them. If your air filter is on the ceiling be careful when this grill comes down. They tend to come out of their seat when swinging down. Pull the filter out of the filter frame. If your system is running when you’re removing the filter, you’ll feel some resistance from the air being sucked into the system — This is normal.
Inspect the filter: Hold the filter up to a light source. If you can’t see light passing through it, it’s time to replace it. You’ll also want to check for any holes or rips in the filter material.
Replace if necessary: If the filter is dirty or damaged, replace it with a new one that’s the same size. Before you throw your old filter away, take a look at what type of debris was collected and how much. This will give you a better idea of your home’s air quality and help you keep track of when you would need to replace it again.

Dust Accumulating

If you start to notice your home is dustier than usual, it might be because your HVAC filter is full and can’t capture anything else.

Allergy Symptoms

If you or someone else in your house starts sneezing more than usual or experiences respiratory discomfort, it could be because a dirty air filter is affecting indoor air quality.

System Alerts

Some newer HVAC systems have filter change indicators that notify you when it’s time to replace the filter. Pay attention to these alerts to keep your system running smoothly.

What Happens if a Home Air Filter Isn’t Changed?

Regularly changing your home’s air filter is important for maintaining an efficient and safe HVAC system. If you don’t change your air filters, you’ll eventually start seeing problems within your system. Some of the most common problems include:

Reduced Airflow

If you notice your HVAC system isn’t blowing our air as strongly as it used to, it might be because one or more filters are clogged.

A clogged filter restricts airflow, making your unit less energy-efficient. When your HVAC system can’t get enough air, it has to work harder than it should. And it could cause serious damage to your system like:

Faster Wear on Smaller Components

When your HVAC system works harder, it causes more wear and tear on its components.

For example, a fan motor can burn out more quickly when there’s more resistance to airflow. This resistance can also cause other components like capacitors and compressors to wear out prematurely.

Regularly changing the air filter helps to distribute the workload evenly, allowing your HVAC system to run smoothly and last longer.

A Cracked Heat Exchanger in Gas Furnace

In gas furnaces, the heat exchanger relies on proper airflow to function correctly. Without enough airflow, the heat exchanger will eventually overheat.

Overheating causes the metal heat exchanger to expand and contract, eventually leading to cracks. Cracks in heat exchangers are dangerous because they allow carbon monoxide to be released into your home.

Carbon monoxide is a colorless, odorless, and lethal gas that can cause severe health problems or even death if inhaled in significant quantities.

Frozen Evaporator Coil When Using AC

When you use your air conditioning, your HVAC system’s evaporator coil removes heat from the air to cool it. Good airflow is required for this process.

If the airflow is restricted because of a dirty filter, moisture on the evaporator coil can freeze.

When ice forms, it further restricts airflow into the system. This creates a vicious cycle where the system becomes less efficient as more and more ice accumulates.

When the ice eventually melts, it can overflow the drain pan, potentially causing water damage or mold growth in your home. This can be harmful to your health and expensive to remove.

Short Cycling

Short cycling occurs when your HVAC system turns on and off more frequently than it should.

When the system can’t breathe properly, it struggles to maintain the set temperature, causing it to cycle on and off repeatedly.

This not only wastes energy but also increases the chances of your unit breaking down more often, ultimately shortening its lifespan.

Pressure Imbalance

An old air filter can create pressure imbalances in your home’s HVAC system. This happens when the system tries to pull in more air through any available opening left in the filter.

As the air is squeezed through, you’ll hear whistling noises. You can also tell there’s an imbalance if you start to hear doors slam unexpectedly.

Higher Energy Bills

One of the less obvious signs of a clogged air filter is a gradual increase in energy bills.

When your HVAC system has trouble getting enough airflow, it uses more electricity to reach the right temperature. And you won’t notice this until you get a high utility bill.

Checking and replacing them as needed can save you money and keep your home comfortable without the extra expense.

Tips for Extending Filter Life and Improving Air Quality

Here are some helpful tips for making your air filters last longer and keeping the air in your home clean and healthy:

1. Use the Right Type of Filter

Choose a filter with the appropriate MERV (Minimum Efficiency Reporting Value) rating for your system and your specific needs based on who lives in your home and what area you live in.

Try to choose a filter with a rating between 8 and 13. Anything more might restrict the airflow too much, and anything less won’t be able to catch smaller particles.

2. Consider Using a Thicker Filter

If the frame where your filter sits is deep enough, try using a 4″ to 5″ pleated filter. Thicker filters last longer than thinner ones because they have a larger area to collect particles, which means fewer filter changes for you.

3. Maintain Your HVAC System

Make sure you have regular maintenance done on your HVAC system with a licensed HVAC company. It’s a good idea to have this done twice a year — right before summer and early fall before winter.

4. Use Air Purifiers

If you’re having to replace your filters a lot, try using an air purifier to catch pollutants and particles before they reach your filters. Adding an air purifier will take some of the workload off your HVAC system and help improve the air quality in your home.

Air Filter Replacement Subscription Services

If you don’t have time to go out and buy filters every month or hate having to climb up a ladder just to remember what size filter you need for the return vent on your ceiling, try using an air filter subscription service.

With a subscription service, you’ll be saving money because you’re buying the filters in bulk.

When comparing the price of a single MERV 11 pleated 3-month filter from Lowes to a four-pack of the same type of filter from a service like Filterbuy, which offers free shipping, you end up saving roughly 33%.

And that’s just for the filters.

If you consider the time you spend driving to and from the store, the overall savings look even better.

The best part about these services is that once you enter the filter sizes you need, you’ll never have to remember them again. Most subscriptions also let you choose your own delivery schedule or set up automatic shipping, so you’re set for the entire year.

Some of the best and most popular air filter subscription services are:

Final Thoughts

Changing your HVAC filter at the right time is the easiest and most effective way to maintain good air quality in your home, keep your system running efficiently, and extend its lifespan.

There’s no single answer for when you should replace your filters because it depends on how much you use your system, where you live, who lives in your home, and what you do inside.

If you don’t know when you should replace your filters, start inspecting them at least once a month. And be ready to change them more often if needed.

This way, you’ll know when they need to be replaced, so you’re not wasting money by changing them too early or straining your system with a clogged filter.

If you live a busy life and just can’t keep track of when they need to be replaced, or if picking out the right filter feels overwhelming, try using one of the air filter subscription services mentioned above.