A furnace filter is a vital component of your HVAC system. The filter sits in between your return air duct and furnace, and it works to trap dust and other airborne particles from getting into the furnace and potentially damaging its components. A high-quality furnace filter can also improve your home’s indoor air quality by trapping pollen, mold spores, dust mites, bacteria and other allergens and pollutants. If the filter is missing or you don’t use the right filter, it could drastically reduce the lifespan of your HVAC system and increase the need for repairs. Therefore, it is essential that you take some time to understand your options for furnace filters to make it easier to determine which one is best for your system.
How Are Furnace Filters Rated?
One of the main things you will need to be aware of when shopping for a furnace filter is how they are rated. Most furnace filters are rated using the MERV (minimum efficiency reporting value) scale, which measures how efficiently it filters out particles of various sizes. On the lowest end of the scale are MERV 1 filters, which are typically only used in window AC units and other similar applications. The scale goes from there up to MERV 20. However, anything from a MERV 17 and above is considered a HEPA filter, and these are only used in very specific situations.
Most residential furnace filters range from MERV 6 to MERV 12. Although you can find filters with a higher rating for this, these are generally only used in certain commercial and industrial applications such as smoking lounges, inpatient care rooms and hospital operating rooms. In most cases, a MERV 12 filter will be more than sufficient to remove most all household allergens, pollutants and contaminants.
Although MERV is the main rating system you will see, there are two other systems as well. These are FPR (filter performance rating) and MPR (micro-particle performance rating). These systems are used to rate sub-HEPA filters, and they work in a similar way to the MERV scale with the higher numbers indicating higher levels of efficiency. The FPR scale goes from 4 to 10, while the MPR scale goes from 300 to 2800. An FPR 4 filter is roughly equivalent to a MPR 300 or MERV 6. At the higher end, an FPR 10 is similar to an MPR 1500 or MERV 13.
Which Materials Make the Best Furnace Filters?
Furnace filters are made out of several different materials. Most filters at the lower end of the MERV scale are made out of fiberglass or aluminum mesh. Although these filters are usually sufficient for keeping dust out of your HVAC system, they won’t do much about pollen, mold and allergens. Most filters that are rated MERV 6 and above are made out of cotton or synthetic materials like polyester. Most cotton filters will be rated MERV 10 or higher as cotton generally provides the highest level of filtration. Nonetheless, you can find some synthetic filters that are also rated just as highly.
Pleated vs. Non-Pleated Filters
The higher rated filters are almost always made out of pleated fabric. Non-pleated filters are usually cheaper, but it is highly unlikely that you’ll find a non-pleated filter that is rated higher than MERV 4. If you’re concerned about air quality or suffer from allergies or a respiratory issue, pleated filters are always the better choice. This is because the pleats increase the amount of surface area available to trap particles and thus make the filter far more efficient.
Are Electrostatic Filters Worth It?
Electrostatic filters are a special type of filter that contains a static charge. All airborne particles also have a charge, and the charge on the electrostatic filter works by attracting these particles to make it easier for the filter to trap them. Most electrostatic filters have a MERV rating of 6 or below. However, you can find some electrostatic filters up to MERV 11 or 12. However, they are often quite a bit more expensive than a similarly rated, non-electrostatic filter.
Is There Any Benefit to Using a Washable Filter?
The lower-rated electrostatic filters are usually washable filters, whereas higher-rated filters are almost always disposable. The benefit of using a washable filter is that they should last for somewhere around four to six years. Although they do cost more upfront, they can save you money compared to the cost you would spend on disposable filters during the same time period. However, they also need to be cleaned every month in order to prevent them from being clogged. In addition, they can also be a breeding ground for bacteria and mold. For this reason, most experts recommend that you stick with disposable filters to avoid this potential issue.
How Often Do You Need to Change Your Furnace Filter?
Disposable filters usually work far better than washable filters. However, this is only true if you are diligent about checking the filter and replacing it regularly. In most situations, it is sufficient to change your filter every 30 to 90 days. However, if your home is exceptionally dusty, you may need to change the filter more often. When replacing your filter, it is also important that you insert the filter in the correct direction or else it won’t work properly. The filter should have arrows that indicate which direction it should be inserted, and these arrows should point toward the furnace and away from the return air duct.
Making sure to change your filter regularly ensures that it will continue to work efficiently. Still, the biggest reason that you need to change the filter frequently is that it can significantly reduce the efficiency of your HVAC system and make it much harder to heat or cool your home. When the filter becomes dirty or clogged, it can severely reduce the airflow. This increases the load on your HVAC system and makes it more difficult to properly circulate air throughout the home. As a result, it can also shorten the lifespan of your furnace or air conditioner.
Choosing the Right Furnace Filter for Your System
Determining which filter is best for your needs is mostly a matter of considering how much filtration you need and how much you’re willing to spend. If you’re mostly only concerned about keeping dust out of your HVAC system and preventing damage, a MERV 4 filter is probably fine. However, you may still want to consider going with something slightly higher if you live in an old home or a particularly dry and dusty area.
If you’re concerned about indoor air quality, you’ll definitely want to go with a filter that is MERV 8 or above. Similarly, if you suffer from asthma or allergies or have any respiratory or breathing issues, it is a good idea to upgrade to a MERV 10 or MERV 12 filter since these will be much more effective at eliminating airborne particles that could trigger an attack or worse your symptoms. These higher rated filters also have the benefit of being able to filter out most bacteria to help keep you and your family from being sick. In this way, you may be able to prevent one family member from getting everyone else sick by ensuring that your HVAC system doesn’t spread their germs throughout the home.
With more than 30 years of experience serving customers in Selma, San Antonio and the surrounding areas, Beyer Air Conditioning & Heating has the knowledge and experience to handle of your HVAC needs. In addition to AC and furnace maintenance, repairs and installations, we also work with ductless systems and VRF systems. Our team can also assist you with improving your indoor air quality. Give us a call today if you have any questions or would like to schedule an appointment.