Stack vent size and number of fixtures

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Stack vent size and number of fixtures

Author: ericsarratt (NC)

I am trying to figure out the stack vent size for a home I am working on. I want to know if the stack vent meets the minimum size code requirements. I tried to read the DFU chart in the North Carolina code book, but I got confused.

I am a septic installer and do a little plumbing repair; I am building up hours to take my plumbing exam. DFU's are not an area with which I am familiar.

The home has upstairs:
Bathroom--sink, toilet, shower-tub
Kitchen--sink w/disposal and dishwasher
Bathroom--sink, toilet

The home has downstairs:
Clothes washer
Bathroom--sink, toilet, shower-tub

The goal of all this is to help me troubleshoot an odor problem for the homeowner.

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Re: Stack vent size and number of fixtures
Author: bsipps (PA) Odors are usually caused by cracked pipe or bad toilet seal Toilet 3 dfu Bidet 1 dfu Tub 1dfu Tub shower combo 1 dfu Shower 2 dfu Kitchen sink 2 dfu Washer 2 dfu
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Re: Stack vent size and number of fixtures
Author: hj (AZ) Odors are seldom caused by a "vent problem". Often they are caused by an unused tub in a room which also has an often used shower.
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Re: Stack vent size and number of fixtures

Author: ericsarratt (NC)

Thank you.

I am just trying to eliminate every possible reason by looking at stack vent size.

***What is the minimum sized stack vent for that number of DFUs? That is where I got stuck on the charts.***

Yeah, I have been thinking toilet seal. I am going to try the rock it the next time I am out there.

I have also considered a dead animal in the HVAC system or the wall.

Edited 5 times.

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Re: Stack vent size and number of fixtures
Author: ericsarratt (NC) I already eliminated the unused tub/fixture. All of them had been used recently and had water in the trap. I did smell a slight sewerish odor when I was there. It is real faint. The home owner really has a sensitive nose.
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Re: Stack vent size and number of fixtures
Author: hj (AZ) does the A/C have a condensate drain attached to the drain system?
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Re: Stack vent size and number of fixtures
Author: ericsarratt (NC) I don't know. I will put it on my list to check.
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Re: Stack vent size and number of fixtures
Author: tomas_churizoe (CA) Often times when I demo a cast iron tub located over a crawlspace I find a dead/mummified rodent or skeletal remains of something that was using the space between the subfloor and the tub as a nesting area. just my 2 cents
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Re: Stack vent size and number of fixtures
Author: ericsarratt (NC) Could you elaborate more on how an AC condensate drain would cause odors? Moldy odor smell perhaps? Thanks.
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Re: Stack vent size and number of fixtures
Author: bernabeu (SC) untrapped or trap seal evaporated cross connection with sanitary piping when a/c runs it sucks up any gasses in the piping and spews them into the air ============================================== "Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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