According to the EPA, the air inside our home is regarded to have up to 5 times higher concentration of air pollutants. Like lungs in your body, your home needs to be able to breathe to make sure that fresh clean air is coming in, and old stale air is going out. Unfortunately, in modern day construction our buildings are built extremely airtight. A good thing, right? Yes, but only If the fresh air intake to the building has been properly engineered and the homeowners know and adhere to requirements involved in keeping that fresh air coming in. Most homeowners that own a home in Whatcom county with a forced air system have the following two components in order to bring in fresh air:

  1. A fresh air duct integrated with your forced air mechanical system (with a damper that can be opened or closed)
  2. A whole house exhaust fan on a timer that works in conjunction with the fresh air intake on the forced air furnace or air handler, in order to exhaust the stale air in the home and bring in fresh air at an equal rate. The air being brought in from the outside should also be filtered before being brought into your system.

The sad reality is that the following scenario likely happens… The homeowner buys the home, nobody ever informed them of the fresh air duct that is meant to be opened in order to allow for fresh air, and nobody every informed them that the pesky whole house fan that they have in their laundry room or main area, is in fact supposed to be running at a set rate to balance the house out. We see all too often that both of these primary functions of fresh air are not being used at all!

Air Circulation

The biggest issue with the filtration installed in HVAC systems is the fact that you need to run the air distribution blower constantly to continually filter and recirculate air. Most homeowners are not used to doing this, may not know how to do this, or may simply have an HVAC system that requires an immense power bill in order to run the fan constantly. For this reason, we highly suggest considering a high efficiency blower motor installation. These motors operate at an incredibly high efficiency (they use roughly the power of a 60 watt light bulb) and allow you to run your filtration 24/7 at lower and quieter speeds in order to bring in the proper amount of fresh air, filter the homes indoor air, and distribute clean air throughout the home at an even rate.

Duct System

Crawlspace environment riddled with fiberglass, moisture and dust

The arteries of your home’s air distribution system is your ductwork. It is well worth it to consider your duct system and the areas that your home may be drawing air from. The average house has a crawlspace or attic which is full of potential air contaminants such as but not limited to (mold, dust, fiberglass, rodent fecal matter etc.). In order to keep your home away from the risk of these pollutants entering your air stream, consider a ductwork evaluation to ensure the home does not have unnecessary duct leakage leading to severe indoor air contamination. This also brings us back to the point of your homes fresh air input. In general, we want our home to be under a very slight positive pressure in order to keep from drawing air in from places that it shouldn’t. That is why it is essential that the indoor stale air that is being exhausted, is also having fresh air brought in at an even rate. If fresh air is not being brought in, your home essentially enters a vacuum state and must draw air from anywhere it can grab, that means your nasty crawlspace or attic!


As an industry we have generally done a sub-par job at making sure we install a properly sized filter in a residential system for the amount of airflow the system is moving. On Marr’s Heating & Air Conditioning installations (unless simply impossible) we include a 4” media filter cabinet and a MERV 8  4” media filter. These filters have the following benefits:

1. Longer run time on one filter due to larger surface area

2. If sized properly, the air velocity across the filter is lower which means that air particulate is more likely to be trapped in the filter instead of making its way through the filter

3. Lower pressure drop on the system. Translated, this means that we generally have lower blood pressure on the equipment which is a good thing

4. When paired with an air scrubbing system and accompanied with proper fresh air input, there is no better system for both your indoor air, and your equipment

What Should You Do?

1. Make sure you have fresh air coming into the building and stale air exhausting out the building

2. Make sure you have a clean air filter and you are keeping up with filter changes on a regular basis

3. Consider the installation of a high efficiency blower motor which will allow for constant running of your HVAC fan at low speeds, which means constant filtration and air cleaning

4. Have your duct system evaluated for leakage and cleanliness to reduce the chance of indoor air pollution, and to optimize your systems ability to filter your air effectively

5. Consider adding a properly sized 4” thick media filter to your system in order to trap more particulate

6. Consider the addition of air scrubbing system to your HVAC system. This technology essentially does what the sun does naturally, including killing viruses, mold, bacteria, odors, dust reduction and can greatly contribute to the overall health and quality of your indoor air. These systems do this through the airborne release of ionized Hydro-Peroxides into the air stream. These systems naturally disinfect and have a 99% kill rate of viruses on surfaces. Though these systems have not had a chance to be tested on COVID-19, this system has been tested and confirmed to kill the following:

  • Mold
  • Tuberculosis
  • Norwalk
  • Listeria
  • Legionella
  • Bird Flu
  • Strep
  • MRSA

See Our full line of Indoor Air Quality products by clicking here!

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