I have a Rheem 86V in the up flow configuration.

I had some sewage backup in my basement and it looks like some of it went up my condensate line into the HVAC because there was no air gap. I noticed a few cupfuls of water on my air filter and at the bottom-front of the machine and when I opened the panel I saw about a quarter inch of water on the floor of each compartment.

I'm assuming the overflow come up from the condensate trap directly into the inducer blower chamber through the drain hose, and then it dripped down on top of the blower. How can I find out how far up the storm/sewage backflow went up into the machine?


I opened some of the yellow caps in the inducer motor and a cupful of water came out of it so it looks like it made it up into the inducer motor chamber and collector box.

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  • 1
    FYI, Alcohol although it kills a lot of things is not to effective in killing mold which is likely. A proper cleaning and misting with hydrogen peroxide, bleach or vinegar would kill any mold. Good Luck.
    – Gil
    Sep 19, 2022 at 14:42

1 Answer 1


It appears from the drawings that the condensate trap is on the floor of the burner compartment, ie above the blower compartment and above the floor by some 18 inches or so.

If the condensate tube is sealed to the drain plumbing then it's likely that reverse flow of sewage would have been capable of pushing liquid up that high. Also, if the sewage backup ejected from the drain plumbing with substantial force, it might have pushed up that high (though you'd probably also have sewage splattered on the ceiling!).

If the condensate-to-drain connection is done in any sane way, then sewage backflow might have wicked up the condensate tube a short distance -- but nowhere near far enough to reach up above the blower compartment and produce dripping down onto the blower.

Staining of the air filter is likely to reach much higher than the "high water mark" because of capillary action. Have a look at the other sides of the blower compartment. There'll be residue there too, and it will give better indication as to how high the sewage rose inside the equipment.

  • I just pulled off the little yellow plug at the bottom of the blower housing and about 10 oz of water flowed out. I imagine this means I will need to have the blower pulled out and sanitized - correct? Probably better to pull the blower out rather than sending a sanitizing alcohol mist into the same hole in the blower housing? Sep 20, 2022 at 10:01
  • These are valid points, but don't answer the question as it now stands. They did answer the more subjective title question prior to the edit. Ah, the joys of a changeable question...
    – FreeMan
    Sep 20, 2022 at 12:31
  • @MonkeyBonkey Well, I wouldn't want to eat off the blower now, but.. if the drainage was nearly clear and there's no evidence of residue or bacterial/fungal growth then I'd simply shrug, say "well that was kinda gross!" and leave it at that. Given that it's all metal the risks are lower than with drywall, insulation, carpets, etc. Considering the variety of things that float through the air, and that all of it passes through that blower regularly, the blower never was a particularly clean and sanitary object anyway.
    – Greg Hill
    Sep 20, 2022 at 18:32

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