Dirt Streaks Around Supply Vents: What Causes It, How to Correct It
When dirt streaks appear around supply vents, a common assumption is that they are caused by dirty filters or ductwork. More often than not, however, this is not the case. So where is this dirt coming from? There are a few possibilities.
- The dirt is coming from the room itself. Air leaves a supply vent at high velocity, creating turbulence in the air. This turbulent air interacts with dust, candle soot, fibers, dander, or other impurities that might be present in the room, and louvers propel this air across a concentrated area surrounding the vent.
- The dirt is seeping from leaking supply boot penetrations. Supply boot penetrations that are not sealed properly allow particulates – insulation fibers, cellulose dust, etc. – from adjacent unconditioned space to be drawn into the airstream. The particles mix with the conditioned air are blown across surrounding surfaces.
Under both scenarios, dirt gradually adheres to wall and ceiling surfaces, especially in spaces where humidity levels are too high or too low.
Solving the Problem
Once dirty ductwork or filters have been ruled out, seal any gaps around the supply boot penetration. If the dirt source comes from within the space, and the problem can’t be easily eliminated (stop burning all those candles!), consider installing collars around the affected vent to direct the air downward instead of across the wall or ceiling.
About E.P. Homiek
E.P. Homiek Sheet Metal Fabrication & HVAC Supply, with two convenient locations in Lakewood, NJ and Union, NJ, provides one- to two-day turnaround on all residential and light commercial ductwork, as well as one- to two-hour emergency fabrication service, rapid delivery, and competitive prices. HVAC parts, supplies, and equipment lines include Goodman, Honeywell, Bryant, Bradford White, Crown Boiler, Daikin, Weil-McLain, Sea Breeze, Generac, Fantech, ZM, A.O. Smith, Hart & Cooley, Malco, Mueller, and many more.
