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dirty sock syndrome with gas heat?

zepfan Member Posts: 398
I have a customer that has a home with gas, forced air heat. Recently the home smells musky even in the middle of winter with reasonable humidity levels (40%) and the furnace, which was verified with a combustion test to be operating safely. As soon as you walk into the home you smell a musky odor that is like a dirty sock syndrome, even though the home is heated with a non condensing draft induced furnace. The furnace, and water heater which are located in the same area, do not seem to smell of this odor at all, and I have checked all plumbing traps, and floor drains, and they are all primed. I have also checked the dryer vent for obstructions. There is no signs of moisture, on the walls floors, etc. I know that odors, along with noises are extremely hard to diagnose on site, and are even harder over a forum such as this. I was posting to see if any one else had every come across this condition, and what was their course of action was. Any ideas would be much appreciated. If it helps the house is located on a non wooded lot, was built in 1970, and is brick with some siding.Thanks to all.


  • Fred
    Fred Member Posts: 8,542
    Have you checked the flue passages in the furnace/water heater for a cooking squirrel, bird or other animal?
  • kcopp
    kcopp Member Posts: 4,441
    How about all the plumbing traps? has one dried out? Floor drain? Its possible w/ the heat on and the humidity low that one trap is letting in sewer gas....
  • Gordy
    Gordy Member Posts: 9,546
    edited January 2017
    Been there done that with a squirrel. Poor **** made it all the way to the WH.....yuck!
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,335
    Hello, If the drain lines are cast iron, you may have rusting at the water line in the vents. I've seen this a few times where the lines rust through at that spot. Does the house sit on a slab or does it have a crawl space? If there is a crawl, there may be some relevant info lurking down there, just waiting for you to find it. :#

    Yours, Larry
  • Jamie Hall
    Jamie Hall Member Posts: 23,433
    All of the above! And check all the duct work.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • BillW
    BillW Member Posts: 198
    If the system has ac, check the condensate pan and the line for the drain from it, also the coil. If the trap has dried out, sewer gas can come in, if the condensate line goes to a sewer. It could be dirty with left-over, dried on biofilm (algae, etc) from the pan not draining properly. A water leak in the ductwork is also one of the usual suspects. Clean the coil and the pan, and consider installing a UV light above the coil. Is the laundry area nearby? It could be "real" dirty socks!