It is up to the customer to make decisions such as which filter to buy, how many to install, and where to install. We are not responsible for misuse of our products. But, with our testing and research we have some recommendations for the most practical and safe use of these filters in your application.
Where to Install
The AIROTRUST Building Mask magnetically attaches to any air vent (supply or cold air return) that sits inside of a 2'x2' ceiling tile. These types of air vents are very popular, especially in office buildings and small businesses.
There are a few different approaches you can take when installing your AIROTRUST units.
Cold Air Returns:
One of the ways we recommend installing this unit is on the cold air return vents only. When you install an AIROTRUST Building Mask to a cold air return vent, you are pre-filtering the air before it is sent back to the HVAC unit where it is again filtered by your furnace filter. This method is great when improving overall air quality and keeping air ducts clean is most important. This method is the safest for your system when you have an ECM motor that will adjust its speed to make up for the increased air restriction.
Note: Since most cold air returns have no obstructions, we recommend using a 4" air filter for best airflow. Also, we recommend covering ALL cold air returns to ensure a balanced system.
Another method we suggest, is placing the AIROTRUST unit on supply vents which can be perfect for small businesses. This is a good way to target the specific needs of an individual or area of your building. This can ensure your customer or employee that the air blowing out of the vents directly towards them has an extra layer of safety.
Note: Since supply vents typically have diffusers hanging below the ceiling, 4" filters usually will not fit. In this scenario, you must use 2" filters. We recommend covering all of the supply vents to ensure a balanced system.
A main concern that our customers have when installing an air filter directly to their system at the ceiling is the added airflow restriction of these filters. Many are worried that with the added airflow restriction, the evaporation coils on their AC unit could freeze. Our findings, that have been backed up by HVAC testing companies, have determined that this is rarely an issue. Especially since most modern HVAC motors are ECM's (Electronically Controlled Motor) allowing the motor to automatically run faster when it detects a restriction in airflow. With an ECM motor, our testing showed that the airflow over the coils is nearly the same even with our most restrictive filters covering all of the cold air return vents. Even for customers without ECM motors who are concerned, an AiroTrust Building Mask with a high efficiency filter are typically very low risk. For customers who need to be as safe as possible, AiroTrust Building Mask's can be used as a seasonal solution during flu and allergy seasons. Furthermore, choosing one of our least restrictive, yet highly effective, filters such as the 30/30 Dual 9 would be a great choice for anyone with concerns. Lastly, choosing a thicker 4" filter (when there are no obstructions) causes much less restriction by increasing the surface area of the filter without loosing the filtration efficiency.
How to Choose the best filter for your application