Many of our customers from the greater Omaha metropolitan area have questions about upgrading the existing standard 1 inch air filter found in residential applications with a more effective 5 inch pleated air filter. As each residence is different with different ventilation ducting, different HVAC equipment, different indoor conditions, and different individual indoor air quality needs, we like to come out and evaluate the system before making specific recommendations.

A standard fiberglass 1” air filter (with a typical MERV rating of about 2) will provide adequate air filtration to protect the HVAC system by filtering out larger dust particles and material that circulates with the air. This level of air filtration will help to prevent any larger materials or debris from getting into the blower fan, from adhering to either the primary heat exchanger or the secondary heat exchanger (for higher efficiency furnace models) or from adhering to the refrigerant coil. For installations with electric furnaces, the air filter also helps to prevent any material from adhering to the electric heating coils.

Some HVAC system installations have enough restrictions in their air flow of the ventilation ducts that the use of any air filter more restrictive than a standard fiberglass (MERV 2 or so) air filter will cause the HVAC system to not operate correctly. Too much restriction in the system can cause a furnace to shut down from overheating or result in an air conditioner coil freezing up. Adequate air flow is essential for the HVAC system to perform optimally.

For those HVAC systems with adequate air flow, then the homeowner can elect to use higher MERV rated air filters that do a better job of filtering out contaminants from the home.

There are a number of reasons why occupants may be interested in upgrading the efficiency of their air filter. Some individuals have an increased susceptibility to indoor air pollutants. Children younger than four can be more susceptible, as can people older than sixty. People that are confined to the home for one reason or another may also need higher indoor air quality. People undergoing chemotherapy and people with compromised immune systems may also want to enhance their air filtration. Many people suffer from allergies, from asthma, from bronchitis, emphysema, or heart conditions. Additionally, there may be a smoker in the house, or a wood burning stove may be used in the colder months, or a household may have a number of pets. All these reasons and many others lead people to want a higher MERV rated air filter.

Many homeowners find that installing a 4 inch or 5 inch pleated air filter with a typical MERV rating of 13 will adequately enhance the indoor air quality of their home. We will need to come out and evaluate the current HVAC system to see what is necessary for us to install a larger 4 or 5 inch pleated air filter. There is often enough room in the return line to accommodate a metal filter box that has a drawer that opens to receive the large pleated air filter. The return line is the large metal ventilation duct that brings air from the home back down to the furnace. The standard 1 inch air filter is often installed in this very location, between the return duct and the furnace. In some applications, there is not room between the return line and the furnace for the metal filter box to be installed. In these cases, it is possible to replace the return boot with a new return boot that has a filter rack built into it. The return boot is the part of the return ventilation duct that connects to the furnace. Still another option is to install a metal box underneath the furnace that will accommodate the larger pleated air filter. For this application to be an option, there must be enough room for the whole furnace to move up about 6 to 10 inches to accommodate the new metal filter box. There would be a lot of metal working labor for some of these options.

By the way, there are a variety of manufacturers who make these larger pleated air filter designs. Some manufacturers make a 4 inch wide air filter. Some manufacturers offer a 5 inch wide filter. We do not favor one particular manufacturer over another. We can usually get any particular air filter or filter box that a discriminating customer wants, but really, any wider pleated air filter with the desired MERV rating will work fine. For one design to achieve a MERV 13 rating, for example, that filter may need to be 4 inches wide. For another manufacturer’s design tom achieve the same MERV 13 rating, that filter may need to be 5 inches wide. They will both provide the same enhanced air filtration. It is not that one is better than the other design.

The video below shows a typical installation of a higher rated MERV pleated 4 inch air filter between the return duct and the furnace. The particular air filter shown in the video is a Honeywell design and is an outstanding filter option, however, homeowners will be just as happy with any of the other similar filter designs.

For more information on Honeywell air filters, refer to the Honeywellstore.com website.

Trane offers a similar 5 inch pleated air filter shown below. It would be recommended to let us evaluate the existing ductwork and identify a filter option that would fit with the least duct modifications necessary to produce the desired improvement in indoor air quality.

Another advantage of these larger pleated air filters is that they can often be changed out every 6 months or possibly longer. Of course the change out frequency is determined on a case by case basis. Some HVAC installations that have restricted air flow cannot support any air filter other than the simplest MERV 2 fiberglass air filter. Any other air filter provides too much resistance to the air flow and will cause problems with the furnace or air conditioner.

A disadvantage of these larger pleated air filters are their cost. They can cost ten times the cost of the simple 1 inch fiberglass air filter.

When installing this larger pleated air filter, or a basic 1 inch fiberglass filter, look on the cardboard border for an arrow that points in the direction of the furnace. This means that the air filter is installed into the air filter slot such that the arrow points to the furnace. It is also advisable to write the date that the new air filter was installed to aid in knowing when to change out the air filter.

There are some other things to consider for homeowners who want to improve their indoor air quality. Taking a proactive role will help to minimize indoor pollutants and improve indoor air quality.

  • Regularly change (or at least check) the furnace air filter.
  • Have an HVAC company out to perform regular maintenance on both the furnace, the air conditioner, the humidifier, and any other HVAC equipment in the home.
  • Use the least amount of household chemicals necessary for the job.
  • Select household chemicals that are the least toxic for the necessary purpose.
  • Clean living and working spaces within the home regularly.
  • Use vacuum cleaners with HEPA filters.
  • Clean carpets one to two times each year to remove allergens, mold, and dust.
  • Control sources of moisture by eliminating or removing them.
  • Have ventilation duct work cleaned periodically by a duct cleaning professional.
  • Install and use exhaust fans in bathrooms, kitchens, and other areas that produce excessive humidity and odors.
  • Repair any plumbing leaks immediately.
  • Remove lint around and under the clothes dryer on a regular basis.
  • With the tightness of newer built homes, it may be necessary to install a device that brings fresh outdoor air into the ventilation system and exhausts a small portion of the existing household air. There are a number of options ranging from a set of small air dampers to an energy efficient heat recovery ventilator (HRV).

For more information on MERV ratings for air filters, refer to this blog.

For more information on what air filter would be best, refer to this blog.

For more information on the Electrostatic Air Filter, refer to this blog.

For a list of HVAC maintenance items that homeowners can perform to help ensure their systems operate well, refer to this blog.

For technical material on troubleshooting a low voltage transformer failure, refer to this blog.

As a trusted HVAC contractor serving the Elkhorn, Omaha, Blair, Bellevue, La Vista, Papillion, Council Bluffs areas, we are happy to come out and install a larger pleated air filter in your residence or even in commercial establishment. We are licensed, bonded, insured, and experienced and we have the highest BBB rating. Call us today at 402-238-2425.

Accurate Heating & Cooling