Help tracking down sewer smell

Old 02-28-17, 11:55 AM
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Help tracking down sewer smell

Hi Folks,

Attached is a pano shot of my utility room which has an on again / off again sewer smell that gets in to the hvac and permeates through sections of the house above it.

Starting from the left is the hot water heater (direct vent), furnace, sink and washer. Furnace condensate pump, furnace mounted humidifier and washer empty in to the sink. I suspect that the problem here is the lack of a vent in the sink drainage. There is a trap, but it probably gets overwhelmed when the washer runs. Any other opinions on what could be causing the odour?

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Thank you!
Old 02-28-17, 12:19 PM
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The lack of vent in the sink may mean that all the water is getting sucked out of the drain. You can install an air admittance valve under the sink above the trap level.
Old 02-28-17, 03:21 PM
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Do you have any floor drains? Without a ball system installed, and no water in the trap, you could have emissions from there.
Old 03-07-17, 10:26 AM
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I ran into a similar situation with mold growth in the condensate drain line. When the AC turned on, it would suck the smell, and smell like dead something.

Some bleach poured down the condensate line every few months solved the problem. The condensate pan inside the unit probably should have been cleaned too.
Old 03-07-17, 10:35 AM
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You may be right that this is a venting issue.

But this question comes up now and then... and as I recall, in some cases it boils down to a dirty, stinky trap. For some people, just cleaning the trap hasn't done the trick / isn't enough... but replacing it with a new clean one has helped them. If the trap is the problem, its cheap and easy to replace. Adding the AAV shouldn't be a big deal, just be sure you install it at a level as high as possible near or above the top of the sink.

And i agree floor drains are another obvious place to check.

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