If you’ve been living in an air conditioned home for a few years there’s a chance that you’ve noticed lines of dirt around the supply vents in the ceiling. These lines of dirt are often said to be caused by a dirty filter but this is usually not the case.

What causes the dirt lines?

There a few sources that can be responsible for dirt streaking around AC vents but the most common source is actually the room where the streaking is occurring. The air that enters the room from the supply vent comes in at such a high velocity that it creates turbulence in the air. Streaking often occurs when the turbulent conditioned air interacts with the dust, dirt, or pet dander that is present in the room. This interaction causes the dirt to adhere to the walls that the conditioned air is being propelled across.

Another source of dirt streaking is unsealed openings after supply boot penetrations. Insulation particles and other contaminants are drawn into the stream and then mix with the conditioned leading to streaks just like the first scenario.

Dirt streaking can be exacerbated by factors such as excessive moisture (can cause certain particles to develop a sticky quality) or very little moisture (causes particles to be attracted to surfaces)

Get rid of the dirt lines

Finding the source of the dirt is the very first step to solving the problem. Inspect the the AC ducts to see if they are dirty or not. If they are clean then you can rule out duct and filter issues. Now you have to figure out whether the dirt is stemming from the room or an unsealed supply boot. If the dirt is coming from the room, anti-smudge rings can be installed to direct the air downward instead horizontally across the ceiling. If the dirt source is external then you the sealing any gaps around the supply boot penetration will usually alleviate the problem

If you are experiencing dirt lines or having any kind of problem with your air conditioning unit, contact us to schedule an appointment. At ACS, we are dedicated keeping you Absolutely Cool, and to provide our customers with the best AC services at affordable prices