How Often Should You Replace Your HVAC Air Filter?

Introduction

Replacing your HVAC system’s air filter regularly is not only important for maintaining your home’s indoor air quality, but ensures that your heating and cooling system runs properly without issues. Regularly changing the air filters on your system is an important, but often overlooked aspect of system maintenance that has real impacts on system health and performance.

Over time, filters can become clogged, restricting airflow and putting strain on your HVAC system. In this guide, we’ll walk you through how often you should replace your HVAC filter, why it’s important, and how factors like filter type, MERV ratings, and impact to your system’s airflow can affect performance.

Why Your HVAC System Needs Clean Air Filters

Your HVAC system relies on a steady, unobstructed flow of air to function properly. The CFM (Cubic Feet per Minute) of your HVAC system is essentially the lifeblood of its operation—determining how much air is circulated throughout your home. Just think of CFM as how much air your system is conditioning per second.

When your air filter becomes dirty or clogged, it restricts airflow and reduces the system’s airflow, which can lead to higher energy bills, decreased efficiency, and even premature system failure.

As CFM goes down, your system is not only delivering less conditioned air to your home, but its working harder to do so.

Filters Become More Restrictive Over Time

Over time, as your air filter traps dust, dirt, and debris, it becomes increasingly restrictive. This buildup of particles not only hampers airflow but also reduces the effectiveness of your HVAC system. As the filter gets dirtier, the CFM (airflow) decreases, making it harder for your HVAC system to cool or heat your home effectively.

Signs of a Restrictive Filter:

• Decreased airflow from vents
• Strange smells in your home
• Longer cooling or heating cycles

To prevent these issues, it’s crucial to replace your filter as it becomes clogged. Keeping a regular replacement schedule ensures your system performs at its best and your indoor air quality remains optimal.

MERV Ratings and Their Impact on CFM

Have you ever noticed that your filters have a rating on them? MERV, or Minimum Efficiency Reporting Value (sometimes FPR), measures how well an air filter traps particles of different sizes. The higher the MERV rating, the finer the particles the filter can trap. However, a higher MERV rating also means more resistance to airflow, which can reduce your system’s CFM.

• Low MERV Ratings (1-4): These filters are designed for basic filtration and generally offer low resistance to airflow, keeping CFM high. However, they do not capture fine particles like allergens or dust. These are the best filters to use for your system, as they put the least amount of strain on the system, but they do so by providing less protection for you and your family.
• Mid-Range MERV Ratings (5-12): As MERV rating reach the 5-12 mark, they become increasingly restrictive, offering better protection at the cost of system performance.
• High MERV Ratings (13-16): High-efficiency filters with a MERV rating of 13 or higher can trap small particles like bacteria and smoke. While they offer superior filtration, they can reduce CFM, especially if your system is not designed for higher resistance.

If you’re using a filter with a high MERV rating (5-16), filters may claim 3 months, but they truly must be replaced more frequently. Filters in this range are already restrictive, but as dust accumulates that restriction increases. We recommend replacing filters in these ranges every month to ensure the system isn’t working too hard.

MERV Ratings and Allergens

If anyone in your home suffers from allergies, the MERV rating of your HVAC filter plays a crucial role in improving air quality. Filters with higher MERV ratings can capture smaller particles, such as:

• Pollen
• Pet Dander
• Dust Mites
• Mold Spores
• Bacteria and Viruses (for high MERV filters)

A filter with a MERV 11 or higher is what’s recommended in order to reduce allergens in your home, which is especially beneficial during allergy season. However, as we mentioned, high MERV filters also create more resistance to airflow, which can decrease system efficiency if not replaced regularly.

Different Types of HVAC Filters

There are several different types of HVAC filters, each with unique benefits and drawbacks. Choosing the right one for your system can impact both your air quality and your system’s performance. Here are the most common types:

1) Pleated Filters (1” and 4”) Pleated filters are one of the most common types of filters used in HVAC systems. They are made from folded layers of material, which increases the surface area and allows the filter to capture more particles. They come in different thicknesses, such as 1″ and 4″, with the 4″ filters offering higher filtration capacity and a longer lifespan.

• 1″ Pleated Filters: Good for general household use and standard HVAC systems.

• 4″ Pleated Filters: Better for homes with high levels of dust or allergens and can last longer before needing replacement.

2) Electrostatic Filters

 Electrostatic filters use static electricity to attract particles, making them more effective at capturing dust, pollen, and other allergens. They are reusable and can be washed, though they require regular cleaning to maintain their efficiency.

3) Fiberglass Filters

 Fiberglass filters are the most affordable option, offering basic filtration. However, they are less efficient at trapping small particles and tend to need replacement more often.

4) HEPA Filters

 High-Efficiency Particulate Air (HEPA) filters are the gold standard for trapping fine particles, including bacteria and viruses. They offer superior filtration but may reduce CFM significantly and may not be suitable for all HVAC systems.

How Often Should You Replace Your HVAC Air Filter?

So, how often should you replace your HVAC filter? While the answer depends on the type of filter and your home’s specific needs, a general guideline is as follows:

• Standard Fiberglass Filters: Replace every 30-60 days
• Pleated Filters (1” and 4”): Replace every 60-90 days
• Electrostatic Filters: Clean or replace every 3-6 months
• HEPA Filters: Replace every 6-12 months (or as recommended by your HVAC manufacturer)

If you have pets, allergies, or live in a dusty environment, you may need to replace your filter more frequently.

Conclusion

Regularly replacing your HVAC air filter is a simple but crucial step in maintaining your system’s efficiency and indoor air quality. By understanding factors like CFM, MERV ratings, and filter types, you can choose the right filter for your needs and ensure your HVAC system runs smoothly for years to come.

“Need help selecting the right air filter or unsure when to replace yours? Contact us today to schedule a professional HVAC inspection and keep your system running at peak performance!”