Sewer Smells In Building

What’s you thoughts?..Here’s what I have been told…My sister works at an accounting office building…She tells me that each morning when she arrives for work and opens the door to enter, there is a very strong sewer smell, and it gets much worse when the furnace is running…She has to open windows to air it out…From what I’m told, it’s a concrete floor, no crawlspace. The furnace ducts are through the floor. There’s been a plumbing/heating company there a few times. They have apparently ran cameras through the furnace ducts and the sewer lines, but never found anything. There are no cleanouts to be found. They removed the toilets to access pipes, etc. They’ve been on the roof checking vents, etc. They tried saying maybe it was from the building sitting empty over the weekends, toilets not getting used, etc…However, my sister has been working through weekends lately, tax season, etc…She’s been there for quite a few years, this is the first year it has happened…She’s thinking on asking the owner about getting another plumbing/heating company out there, as she feels the other guys may be wasting time, trying to soak up a few dollars, etc…Any ideas?

Floor drains anywhere in building? If those are dry that smell will come up.

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The floor is all carpet from what I’m told. They’ve moved furniture, looking etc…

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I was thinking in bathrooms.

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I will message her.

Junior, maybe a floor drain somewhere e.g. bathroom, utility room, mechanical room, etc., may have dried out and is now open to the sewer.

Mineral oil works well as it doesn’t get rancid and doesn’t evaporate.

But, you would think that the company they had in there would have checked that/those.

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You would think! :grinning: I sent her a message.

Would it make sense to smell stronger when the furnace kicks in?

It depends on where the floor drains are relative to the return air grills and probably something else that I can’t think of right now. :smile:

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Thanks guys! I’ll see what she comes back with and/or see if she can take pictures if needed! :grinning:

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I am thinking floor drains also. One of our large manufacturing plants had that problem in the office. It was a couple of floor drains hidden by the carpet that dried out.

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Talking to her now. She said the plumbing/heating guy tried pouring something down the floor drain in the furnace room. It’s the only floor drain they know of. Apparently, they checked all pipes, checked for vent blockages, etc…Ran cameras…Changed the wax seals on toilets, etc…

I’ll mention this as well. They had moved furniture, etc, but may have missed something if buried under carpet. Thanks Joe!

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Joe has a good point. Have them look for any slight circular slope in the floor under the carpet.

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Message is sent! :grinning:

Check the condensation drain trap. Maybe dried out sucking sewer gas back into the furnace

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Thanks Randy!

The floor drains and HVAC drain are all good spots to check. Are there any wall cleanouts? Around here they are usually covered with a 6 to 9 inch diameter chrome disk. They can often be hidden behind heavy furniture and have seen the actual clean out not reinstalled…

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Apparently, they didn’t find any cleanouts. They moved furniture around, etc. It’s a building my sister works at in Alberta. I’m not there to look around. I text her a list of extras to look out for, etc. She was asking, because the plumbing/heating guys been there a few times and haven’t solved it.

Does the furnace get combustion air from inside the office and exhaust it to the outdoors, creating a lower pressure indoors? Are there any AAV’s (studor valves) under sinks or other locations?

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