Bad smell in air ducts

By · April 25, 2010 · Filed in Industry News

What should you do if you have a bad smell coming from the air ducts? One interesting fact is, in spite of all the advances in science, the only smell detector is your nose. However, instruments can measure volatile organic compounds (VOC)s, which may be in order if an initial investigation still leaves questions. There are many potential sources of bad smells coming from the air ducts:

  • Odors drawn in from the a musty crawlspace or attic
  • Skunk spray or dead animals in the HVAC unit or ducts
  • Plumbing vents tied into HVAC
  • Dirty sock syndrome

Damp, musty crawlspaces can impact the living space and duct work, especially if the ducts are not air tight, and they usually are not. When the return duct is leaky, it can suck air from the crawlspace when the air is being pulled to the unit. When the supply ducts are leaky, they can actually suck air in through the venturi effect. A qualified inspection will determine if your duct system can be repaired or needs to be replaced.

Sometimes a dead animal smell in the ducts is, well, a dead animal. Dead animals leave behind nasty contamination and need to be handled accordingly. Similarly, a skunk can spray the AC unit or ducts. The smell can be very obnoxious and if not treated by trained professionals, can linger for a very long time affecting the whole house and all the contents.

While pretty unusual, and certainly not in accordance with building codes, sometimes the plumbing vent can be tied into the condensation line from the HVAC unit. The tale-tale sign is a sewer gas smell in the ducts when the unit comes on. The unit actually sucks sewer gas through the condensation line into the duct system. The fix is to disconnect the two and reroute the condensation line.

The dirty sock syndrome is when there is a strong smell of dirty socks when the AC unit is running. Clever name, huh. The cause is usually from standing water in the evaporator coil pan. This happens when the condensation line is clogged, when the pan is not tilted enough toward the drain end or when there is too much debris in the pan to let it drain properly.

As you can see, a bad odor in the ducts doesn’t always mean cleaning the ducts will solve the problem. Should you have your air ducts cleaned? Probably, but make sure you have addressed any other issues that may need to get fixed.

Call 615-371-5355 to schedule an inspection to identify the cause and get a price for the solution to the bad odor.

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