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Preventative Maintenance Tip: AHU filters

This is the first post in a series of posts that will provide you with (mostly!) quick and easy ideas for increasing the performance of your building as well as detailing WHY these actions will help you.

When was the last time you had your maintenance staff check and change the filters in your air handling unit(s)? Perhaps you have one of these plans in place for when to change filters:

  • at a predetermined static pressure drop across the filter

  • based on visual inspections

  • time driven, i.e. once a year

If you do have a plan in place: GREAT! If not: it's time to start!

However, there are a few issues that can arise if now, or at some point in the past, filter maintenance has not been done in a timely manner.

Let's explore why you don't want your filters to get to this state!

Now this is a dirty filter!

It is important to keep the filters in rooftop and indoor air handling units (RTU/AHU) clean because dirty/plugged filters are responsible for the following:

  • An increase the pressure drop across the filters. This causes fans to work harder to maintain airflow to your building. This increasing energy use.

  • Increased fouling of the RTU/AHU heating and cooling coils causing increased maintenance and reduced efficiency.

  • If you have a variable air volume (VAV) box system in your building, the dirty air that gets past plugged and damaged filters can plug up multi-point pitot-tube sensors at the VAV inlet which measure airflow and can also plug VAV reheat coils. This reduces the performance of the individual zone control.

  • Increased allergens within your building. Regularly changing filters is an easy way to improve the air quality for your occupants!

  • If you have discharge air smoke detectors in your ductwork these sensing ports can become plugged from non-filtered airflow and limit functionality of these safety devices. Your smoke detectors may not work properly!

Is your current filter-replacement schedule up to par?

  • Do you have a plan in place for replacing filters? (Visual inspection, time-driven, pressure drop?)

  • Does it include ALL filters in the system?

  • Does maintenance even know WHERE all the filters in the system are?

  • If you find a filter has NOT been changed for a long time, do you have a plan for checking discharge air smoke detectors and other equipment to be sure they have not been damage?

Be sure to add filter inspections to your preventative maintenance plan! It costs much less in the long-run to keep up to date on maintenance.

We will be sending out more tips in this series. Click here to subscribe to our mailing list to receive these posts to help you increase the performance and efficiency of your building!

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