Which Air Filter is Best for the Home? | Air Filtration
Most people don’t think much about their furnace (or A/C) air filter, but considering that indoor air quality is often significantly worse than outdoor air quality, it may be a good idea to put some serious thought into our home’s air filtration system. Choosing the best air filter for your home translates to better indoor air quality, higher energy savings, less repairs, and more peace of mind.
When shopping around for your HVAC air filter, it is important to consider many factors, including the type and size of air filter, your air filtration needs, and the heating and cooling system you currently have. Although many people think that choosing the best air filter is as simple as finding the air filter with the highest MERV rating, there are many problems with this, as you will see.
What is MERV?
MERV (minimum efficiency reporting value) ratings were created by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to measure the efficiency of air filters at removing airborne particles .3-10 microns (one millionth of a meter) in size. MERV ratings measure the effectiveness in removing particulates in the air, such as dust, dander, mold spores, clothe fibers, bacteria, pollen, and tobacco smoke.
MERV ratings range from 1-20, with 1-12 ratings normally used for homes and business, while MERV ratings above 13 are typically used for hospital and surgery settings.
This does not necessarily mean that a higher MERV rating means a better filter for your home. In fact, a higher MERV filter could end up causing damage to your system and making your indoor air quality worse, not better. It is important that your furnace (or A/C) filter fits snug in its compartment.
The main reason why you need an air filter is actually not indoor air quality, but rather to keep your heating and cooling system clean and running efficiently. When replacing your air filter, make sure you have the right dimensions so there is no air bypass around the edges. Higher MERV ratings usually mean a thicker filter, which is great for air filtration, but not necessarily great for your HVAC unit.
Filters with a higher MERV rating tend to be a lot thicker, which may restrict needed airflow to your system. The filtration might be better, but the slower airflow could impact your unit’s energy efficiency, with the potential for overheating and freezing condenser coils. A dirty and clogged air filter will also raise your energy bills and raise the risk of overheating and freezing essential parts of your system.
For most homes, a filter with a MERV rating of 7-13 is recommended. You generally want to stay away from any filters rated below 5 and only use a filter rated above 13 after speaking with an HVAC professional.
Reusable/Washable Air Filters
Residential air filters com in two basic types: disposable and reusable. In general, disposable filters are more effective and have higher MERV ratings, but reusable filters last longer and end up costing less in the long run. Additionally, washable filters require finding removing the filter, finding an appropriate area for cleaning, rinsing it with a garden hose or other cleaner, allowing it to dry, and then putting it back in your system. Watch this video to learn how to wash your reusable filter:
The only upside for choosing washable, reusable filters is having a lower environmental impact and possibly saving some money. If you are looking for the best air filtration option with the least amount of maintenance, most HVAC professionals recommend disposable filters.
With that in mind, let’s go over some of the most common air filter types.
Common Air Filters
These filters are very popular because they are cheap and readily available. You can pick them up for just a couple of dollars at your local hardware store. As you might expect, however, there are more effective filtration options out there. These disposable fiberglass filters are mainly used to prevent larger pieces of dust and debris from gunking up your system. They do very little when it comes to improving indoor air quality. MERV rating: 1-4.
Pleated Polyester (disposable and reusable)
These are the second most popular filter on the market and are a little bit more expensive, running you around $5. These pleated filters are made from cotton or polyester and have a larger surface area, allowing it to capture more airborne contaminants. The larger surface area, however, also means more restricted airflow. Airflow is very important to your system as discussed above, affecting your energy bills, HVAC lifespan, indoor air quality, and overheating. Speak with a HVAC professional before switching over to pleated polyester filters. MERV rating = 5-12.
Electrostatic (disposable and reusable)
Most often coming in disposable form, these electrostatic air filters use the principle of static electricity to attract and capture more airborne particulates. These self-charging cotton filters are great for homes with smokers, pets, and people with allergies and respiratory problems. They are a bit more expensive at $10-$15, but way more effective at air filtration than either fiberglass or polyester filters, and can even inhibit the growth of bacteria. MERV rating: 8-12.
HEPA (high efficiency particulate arrestance)
HEPA filters are the best filters you can find, which is why they are mostly used in medical facilities. However, families that have severe allergies, respiratory ailments, or autoimmune disorders, may find themselves needing a higher quality air filtration system. Unfortunately, HEPA filters are very thick and often require significant modification to your existing HVAC system. If you are considering replacing your furnace or air conditioner any time soon and want HEPA filtration, make sure you mention this to your HVAC installer. They may need to redesign the system to fit the larger HEPA filters. HEPA filters run around $100, but only have to be replaced about once a year. MERV rating: 14-20.
Whatever air filter that you choose, make sure to consult with a professional heating and cooling technician first. There are many variables to consider when changing your system’s filtration system.
REMINDER: No matter what air filter you have, it is extremely important that you remember to change it frequently. The general rule of thumb is to check your air filter every 30 days and wait no longer than 90 days to replace it. A clogged air filter will impede airflow and cause many of the problems already discussed: overheating, frozen condenser coils, shortened HVAC lifespan, compromised indoor air quality, and higher energy bills. Set calendar reminders and write the date of replacement on the air filter itself to remind yourself of this important monthly maintenance task. Watch this video to learn how to replace your HVAC filter:
Another important thing to remember is to schedule regular heating and cooling tune-ups from a professional. Sign up for Gold Medal Service’s Total Care Club for automatically scheduled service appointments, discounts on repairs, front-of-the-line service, and more!
If you really want better indoor air quality, consider purchasing the Lennox Signature Collection PureAir air purification system – the only indoor air quality product that removes all three sources of contaminants (particles, bioaerosols and odors).
Contact the professionals at Gold Medal Service for a professional indoor air quality assessment and consultation. We will make sure you have the best filtration and ventilation system for your home.