Did you know your filters are not there to give you clean indoor air?

The primary purpose of a filter is to protect HVAC equipment, not to improve indoor air quality, as many homeowners have been led to believe. Many furnace manufacturers recommend that you use a low-cost fiberglass filter, but when I asked a representative of one major maker, his response was “no comment.”

Perhaps this was because high-efficiency filters that are too good may actually slow airflow across the heat exchanger, reducing the unit’s efficiency, raising your energy bills, and causing furnace damage due to overheating. Similarly, a high-efficiency filter can freeze the condensing coils on an AC unit. (A dirty filter can do the same thing.)


Are you surprised that the filter in your HVAC unit isn’t there to give YOU cleaner indoor air but only to protect your HVAC system? What can you do to get cleaner air you ask, many homeowners are also purchasing air filters for their vents. These optional filters are bought in sheets which may be then cut to fit both register and air return vents throughout the house, a timely chore to say the least. VentMask filters eliminate the need to trim and remove the vent regiter to be used, our Peel-N-Stick application make them easy to use and more importantly change when they need to be.  Keep in mind that while helpful, vent filters are not ideal for all homes and may or may not be worth the investment.

Many folks ask, “What is the difference between a vent register and a vent grill?”   If your home has central heating and air, it contains a series of openings used to transfer air to and from the air conditioner and furnace. These openings are the grilles, vents, and registers. 


How Air Registers Work

Air registers have slatted openings in the floor, wall, or ceiling that a user can control using an adjustable damper. Typically, a rolling guide or a lever on one side of the vent, the damper opens or closes access to the air duct for airflow management. These openings do not bring air back to the HVAC system, but deliver heated or cooled air into a space.


Vent register…has slider or arm that allows you to open or close vent.

Vent register…has slider or arm that allows you to open or close vent.


Heating and Air Grilles

Grilles are permanent, unmovable fixtures that may serve an air supply or return function. Grilles are found in residential ceilings and walls, but a company may install them in floors in certain cases. Depending on the system setup, a home may have one larger return grille or several small ones throughout the home. The air return is a grille that serves one purpose – to pull air back into the HVAC system for reuse.



Vent grille….no fin adjustments.

Vent grille….no fin adjustments.


Weighing the Pros and Cons

As with any optional component of an HVAC system, vent filters have both positive and negative qualities which may affect whether they will benefit your home. Knowing these qualities will help you make a more informed decision before making a purchase.

Benefits of Vent Filters

Adding vent filters to your home serves as an extra line of defense against dust and allergens. These particles can enter the ducts through cracks and bypass the main furnace filter. Dust can also accumulate in the vents during periods of inactivity, further polluting your home.

Drawbacks of Vent Filters

The biggest drawback of vent filters is restricted airflow. Filters slow the passage of air. As particles build up on them, the amount of obstruction increases. This can cause your system to work harder, using up more power and potentially overheating components.

In addition, these filters will require regular changing, just as your main filter does. This, in turn, requires you to access each vent that contains a filter several times per year. While that might not be difficult in some cases, it can pose problems when the target vent is in a difficult-to-reach location, such as high on a wall above furniture.

Consider the MERV Rating

When choosing a vent filter, you should always aim for a MERV (Minimum Efficiency Reporting Value) rating of 6 to 8. The lower the number, the less air is obstructed, although it will also allow more particles through. This rating scale is an industry standard and is an excellent way to balance filtration and airflow restriction.


Filters with a MERV rating of 6 are the lowest quality recommended for household use. Compared to a basic fiberglass filter, MERV 6 filters perform approximately eight times better. Filters at this rating can filter out numerous large particles, including:

·       Allergens such as pet dander, pollen, and dust mite debris

·       dirt and dust

·       lint

·       random small debris

MERV 8 (What VentMask filters are rated!)

While air filters for your home may have a MERV rating of up to 13, MERV 8 is the highest recommended for vent filters. These filters still allow for good airflow, but are approximately 20 times more efficient than fiberglass filters, making them an excellent choice for homes where family members smoke or people are more allergy-sensitive.

However, these do not eliminate all allergens, only large-particle ones.

Are Filters Right for Your Home?


Air filters can make a big difference in some situations, but do not always solve air quality problems. Air quality can be caused by a number of sources, and your furnace filter does a good job of protecting from airborne particles under normal circumstances.

VentMask Clean White

VentMask Clean White

When to Get Vent Filters

Vent filters can be an excellent way to augment your main filter, and are useful for homes where your HVAC system remains off for much of the year.

In such places, the filters help to reduce dust accumulation in the vents themselves. This may also help reduce the heated dust smell which occurs when your furnace is first turned on after sitting for a long time.

While they cannot eliminate the problem entirely, vent filters can also help reduce airborne allergens such as pet dander and pollen. These particles normally get pulled into the return vents and are caught in the furnace filter, but they can also be pulled into cracks in your ductwork and forced into rooms through the registers.

When to Avoid Vent Filters

Sometimes, using vent filters in an older home is no better than placing a bandage over a broken bone. The ductwork may accumulate holes or cracks over time, and seals can break. A common symptom of this is a home where rooms gather dust quickly, while the furnace filter stays relatively clean.

In such cases, vent filters can catch a large percentage of particles, but the leaks in your ducts will also be impacting your heating bills. Getting the ductwork checked and repaired is the best solution and may prove cheaper long-term.

Another problem in older houses is often the furnace itself. Furnaces must be fed air in order to keep from overheating or struggling to remain active. In such cases, adding filters to your air returns may reduce the amount of airflow enough to affect the furnace.

VentMask realizes this, however providing clean indoor air for your family is our top priority. Our solution is to use filters in the most strategic areas of your home. Use a vent filter in your bed rooms, living rooms, library or study and TV room. Do not use a vent register filter in your bath room, kitchen or laundry room. This means the rooms you spend the most time in will have filtered air and the rooms that you do not filter provide a open unobstructed back flow for any resistance caused by the added filtration.