Thread: Plumbing vent stacks

I was at a house today checking radiant heat in a driveway. The house was 10,000 sq ft with 9 bathrooms. The guy was showing me around and I mentioned it smelled like sewer gas in the home. I was curious about the venting so I looked walked the roof and they had one stack, that's it. The gentlement with me wanted to know if it was possible to have all the vents tied into one. Not likely. Have you seen anything like this.

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Never!

Originally Posted by mathew stouffer

I was at a house today checking radiant heat in a driveway. The house was 10,000 sq ft with 9 bathrooms. The guy was showing me around and I mentioned it smelled like sewer gas in the home. I was curious about the venting so I looked walked the roof and they had one stack, that's it. The gentlement with me wanted to know if it was possible to have all the vents tied into one. Not likely. Have you seen anything like this.

Not likely ... on that size house with 9 bathrooms. Possible, but the vent the others are tied into needs to be sized appropriately for all the vents connected to it.

More likely they have AAVs installed at the other places. And one or more AAVs may be off, not installed properly, etc., OR ... they may have tied all the vents back into just that one. Did you look in the attic?

I didn't really look for an attic, but the majority of the home had vaulted ceilings. The one vent stack was a three inch, i think. The roof was very slippery and it was raining so I could not get close. I was just killing time waiting for the driveway to heat up. The place was a money pit, 1 year old and they have put over 300k into it for repairs. The one vent stack was on the opposit side of the home and in the other side there were at least three bathrooms. So I told the guy there in no way they could be vented.

Originally Posted by mathew stouffer

So I told the guy there in no way they could be vented.

"no way they could be vented"

That is a very strong statement, one which I would not want to back up.

There are several ways it COULD be vented properly, so, *more likely* it they were vented - just not "vented properly".

Originally Posted by mathew stouffer

I was at a house today checking radiant heat in a driveway. The house was 10,000 sq ft with 9 bathrooms. The guy was showing me around and I mentioned it smelled like sewer gas in the home. I was curious about the venting so I looked walked the roof and they had one stack, that's it. The gentlement with me wanted to know if it was possible to have all the vents tied into one. Not likely. Have you seen anything like this.

The more likely reason for sewer gas smell is long term unused drains or baby spiders caught in AAV seals.

I have inspected several homes that have set empty for more than a year. Both toilet traps and laundry drain traps were dry, bad smell!

As an experiment I covered all of my vents with plastic grocery bags and rubber bands. I then filled all of the sinks and two tubs with water. Then I drained everything at once and flushed two toilets. The most I heard was a faint gurgle at one of the sinks, no smell. When that sink was drained by itself there was no gurgle. When the sink is used to wash hands or empty a glass of water there is not enough volume to siphon the trap. I grew up in a house that had S' traps and never had any problems.

My house is on city sewer but was originally on septic. When I was on septic the sewer smell was faint but obvious when standing on the roof and above the main vent stack. Now on the city sewer I can put my nose in the vent stack and not smell a thing. The flow of sewer down the main line in the street creates a negative pressure is my best guess.

Yes I will still follow plumbing code and report venting problems I find during inspections. Just sharing some of my observations.

Mathew

I agree with EC Jerry in that making positive statements to clients and their legal representatives while on the job without the benefit of proof through visual confirmation or other means would be like chumming in a sea filled with finned backed suits with "Esquire" after their names.

Well I did leave a little info out that would make more sense. It was a spec home and the guy ran out of money. I was not inspecting it just checking the driveway for radiant because they have to rip if up. When the management company went into the house and ran the sinks and jetted tubs water began to run out of the walls. The builder never completed the plumbing installation so the drain line just terminated behind the drywall. So that is how the conversation began and the guy asked about the smell. I wish I had had my camera to take a pic of the boiler room. You had to step over exposed radiant lines just to access the boiler room.