Plumbing question for the pros?

[wet hull]

On a job we just completed about 3 months ago. Master bathroom remodel with dual sink vanity. When owners turn on water to sink on left side we get a bad sewer smell immediately for about 5 seconds. Here are the facts

Everything outward from initial plumbing stack going to downstairs is brand new pipe, traps, drains.

Right sink tied into vent to roof. Left sink has a stutter vent do to HVAC duct in way of attaching both together and staying code compliant.

Water flows freely

No smell when water not running

No clogs, pipes still look new. P traps holding water as they should when water off.

Plumbers pulled all drains, traps just to see if they missed something. They are absolutely baffled. Smell doesn't happen on 2nd sink or showet drain.

Have any of you pros experienced this before?

 

[Ultra...Good]

Sounds like something is up with the drain line and when you first turn on the one, it temporarily sucks the trap on ther side dry which would explain why it is a temporary sewer gas smell.

Whether it is not piped right or pitched right it is hard to tell without seeing it.

 

[cofooter]

Or there is bacteria trapped down there and only smells when it first gets wet.

 

[DirtyWhiteDog]

Change the stutor valve, its letting too much air out. Drain line from legft sink is probably long enough to trap the sewer gas, then when the pressure changes from trap water running stutor stays open instead of burping small amounts of air in.
Not a professional plumber, just how I understand how the valve works.

 

[NicPaus]

Change studor vent and see if it fixes it.

 

[wet hull]

All my thinking was towards studor vent as well. Only issue is getting to it now without destroying all finish work.

 

[Justfishing]

Post pictures. Is the water from one drain sucking water from the other trap?

 

[DirtyWhiteDog]

Stutor is "supposed" to be accessible, for that reason make the that installed it fix it.

 

[wet hull]

Stutor is "supposed" to be accessible, for that reason make the that installed it fix it.

They will fix it. No worries there. Looking for pics. Not sure I grabbed one of that stage. Im the worst at grabbing progress pics