For most homes, a MERV rating between 8 and 13 strikes the perfect balance between filtration, airflow, and cost.
In most cases, a MERV 11 air filter isn't too high for residential use. Generally speaking, anything under a MERV 13 air filter should provide very efficient air purification in a home without impacting airflow.
MERV ratings for air filters range from 1-16 with the higher ratings being more effective at filtering pollutants. In general, HVAC professionals will recommend MERV filter ratings between 8 and 13 for home use. This is because the higher the MERV rating, the more an air filter can restrict airflow.
This will vary depending on your HVAC system. Still, a MERV value of 9 to 12 is generally recommended for most household HVAC systems. You can also consult your HVAC system's owner's manual to determine the appropriate MERV rating for your system.
A common question among homeowners is, “What is the max MERV for a home?” Generally, a MERV rating up to 13 is typically the upper limit for most homes. Using filters with a MERV rating higher than this can be too restrictive, potentially impeding airflow and straining your HVAC system.
MERV 13 Air Filters
Filters with higher ratings are intended for healthcare and laboratory environments with excellent air quality and HVAC systems that can handle highly efficient filters. Using a filter above MERV 13 in a home is unnecessary and can restrict airflow and damage the HVAC system.
ASHRAE has similar guidance, which is to "use combinations of filters and air cleaners that achieve MERV 13 or better levels of performance for air recirculated by HVAC systems." The simplest way to meet this guidance is to use a MERV 13 filter in your appropriately-designed HVAC system, if the system is able to ...
Yes, higher MERV filters are more restrictive and reduce airflow. If you make adjustments to the HVAC system it can eventually handle the increased resistance.
A home with no pets, smoke, or allergies will do just fine with a MERV value of 1-7. If you have pets or someone in your home has significant allergy problems, you may want to consider a higher MERV value, between 8-10. Homes with smokers or a wood-burning fireplace should have a filter in the MERV 11-13.
Because not all HVAC systems can use HEPA filters, air filters with a MERV rating of 13 to 16 are the best option to trap pollen, pet dander, mold spores, and dust mites, and they're highly effective for reducing allergens and improving indoor air quality.
These high-quality filters trap particles as small as one micron, including Legionella and humidifier dust. MERV 9 to 12 filters are the best filters that a residential HVAC system will accommodate without serious system modifications.
Generally, this is how long a filter lasts based on MERV ratings: MERV 1-4 furnace filters should be replaced once a month. MERV 5-8 filters need to be changed roughly every 3 months. MERV 9-11 filters require replacement every 6 months.
ASHRAE currently recommends using a minimum MERV 13 filter, which is at least 85% efficient at capturing particles in 1 µm to 3 µm size range. A MERV 14 filter is at least 90% efficient at capturing those same particles.
You may not need a MERV 11 filter or higher unless you have specific air quality issues or allergies. For the average household, a MERV 8 air filter can be good enough. You'll want to think about factors like how often you want to change your filters and what type of material do you want filtered out of your air.
The MERV 11 air filter is the wrong choice for people who do not own pets and do not have any breathing trouble; this is because it can lead to restricted airflow. Air filters with higher ratings can also have negative effects on HVAC components.
Furnace filters with a MERV 8 rating or higher can effectively remove pet dander from the air. On average, MERV 8 filters remove 85% of large air particles and 50% of small particles. The higher you go the better the filtration will be, but we don't recommend going higher than MERV 13.
How Often Should You Replace Air Filters? The short answer is, you should at least change your filters once a year, preferably every three to six months. But it also depends on how many people are in your home, the appliance in question, if you have pets, and if you or others living with you are sensitive to allergies.
Air filters with higher efficiency ratings may do a better job clearing the air. Still, they'll also force your HVAC system to work harder, resulting in performance challenges and higher energy bills.
A MERV rating between 9-12 or even higher would be good if someone in your family suffers from allergies or asthma. A MERV 11 filter can trap particles such as dust, dust mites, pollen, pet dander, mold spores, lint, and larger particles.
High-MERV filters increase the static pressure of your system, and if the ductwork is already marginal, this can cause the airflow to drop to a level where the temperature exceeds the furnace's limit.
Disadvantages of a High Flow Air Filter:
It can also increase the amount of dirt/dust in your engine oil that can increase the wear of the engine's moving parts. Another problem with the High Flow Air Filters is that water splashed from the road can be soaked by this kind of filters.
A 1” MERV 13 pleated filter has a pressure drop of around 0.27, and a 1” MERV 8 has a pressure drop of around 0.14.
Pleated filters with MERV ratings from 5 to 8 are classified as medium filters and are the most common in residential HVAC systems.
1“ Throw Away Filter
1” throw away filters are typically a MERV 2 rating. Most Bard products can use either a 1” throw away or a 2” throw away filter. Upgrading from a 1” filter to a 2” filter will give you a higher filtration value. Remember to reference your manual for what your Bard product is capable of handling.
In some cases, using an air filter that is too restrictive for your system may cause low air flow problems as well. MERV 13 is the highest MERV value safe for residential furnaces; the higher ratings are used primarily in commercial units.