Can Whole House Air Filters Damage HVAC Equipment?

This question came up in a recent Green Builder Media webinar on Building Science from listeners concerned about the impacts of various filter media on airflow through ducted systems.

carrier MERV 15 filter

Q: I’ve heard that certain air filters cause airflow restriction and damage to HVAC equipment.  I read that if the face area of a filter medium is larger, and an ECM motor is used, the flow reduction is less significant.

We asked the technical experts at Carrier to respond Here’s what they had to say:

We do not have specific test data showing that restrictive air filters can damage an HVAC system, or that a deeper filter and ECM motor will limit airflow reduction from the filter. That said, we agree that restricting airflow can cause wear on the blower motor, increase energy use and potentially damage other components. An air filter that minimally reduces airflow is generally a better option.

There are a number of factors to consider when it comes to airflow through a filter –

  • pressure drop (resistance to airflow – lower is better),
  • filter depth (deeper media infer more surface area)
  • construction/type of media and efficiency (MERV rating).

These factors all affect filter performance. For example, a high pressure drop can result in the blower motor having to work harder to move the air through the filter, which could cause more wear on the blower and higher energy costs. Filter depth can also affect initial pressure drop – by increasing the depth of the filter, the surface area is increased allowing more room for the air to pass through.

By comparison, the Carrier Infinity air purifier uses electrostatic charging of particles in the airstream entering the air purifier, and electrostatic charging of the media to capture particles on the filter.

The charged particles are attracted to the fibers of the media in our filter, rather than relying on the chance they will collide with or not fit between fibers. The attraction principle of the particles to the filter media fibers enables us to have more loosely constructed fibers in the media, which allows more airflow through the filter, while still achieving a very high efficiency of MERV 15. This results in a highly efficient filter with a very low initial pressure drop and a long filter life.

Another advantage to our technology is that it kills viruses and bacteria that are captured on our filter media.* There are filters on the market that come with an electrostatic charge from the factory, but the charge can wear off over time. Our Infinity system provides a continuous charge for the life of the filter.

To learn more, click here.

* Based on third-party testing (2012) showing 95% of particles size 1.0 to 3.0 microns captured. Based on third-party testing (2012, 2007) showing >99% kill rate for common cold surrogate, Streptococcus pyogenes and human influenza.

Source: Kristoffer Nielsen, Carrier