Code Question for Plumbers

Zman

I ran into this situation in a condo building I do consulting for. Would any of the plumbers out there be willing to weigh in on the situation? Basically, a contractor tied a washing machine into a dry vent stack that is capped off the bottom for future use. When the washer discharges, the water finds its way (sometimes) through the vanity vent on the floor below. What are the code implications of turning the dry vent into a wet vent?
TIA
Carl

Alan (California Radiant) Forbes

The UPC is pretty specific on wet venting and what you have there wouldn't fly. Clothes washers are 3 fixture unit fixtures and max on a wet vent is 2 fixture units. There are fixtures on different stories using the vent (not allowed) and there are more than 4 fixtures vented.
Would it work? I don't feels comfortable saying yes on this one. When the clothes washer is discharging, it would very likely disrupt proper venting of the other fixtures and cause some traps to be siphoned.

Intplm.

Tying into the vent where it is [ capped ] as in your drawing is code-compliant.
The vent above should then be extended/tied into the above vent stack shown.

Alan (California Radiant) Forbes

Yes, there's nothing wrong with venting the building drain. They do it in multi-residential buildings to reduce sudsing from clothes washers.

Mad Dog_2

Misdemeanor...felony...Easy...Doing something shady with Natural gas, yes. I'm going to take a good look now.  Mad Dog 🐕 

Danny Scully

How close is the washing machine to the lav @Zman ? 

Mad Dog_2

Yeah...A clothes washer is pushing it on the D.F.U.s (Drainage Fixture Units). On high rises in NYC we sometimes  dump a small load like a Drinking fountain down on every floor in to  a Vent stack to flush scale over the years.  We call it "Washing the vent stack."

That being said, Clothes washers waste Hair, Lint, Strings, et cetera in to the waste line.  This will eventually become a stoppage issue IN THE VENT STACK! This could cut air flow to many other fixtures and cause big drainage problems.

Additionally, tying in to The "suds pressure zone" can cause Soapy foam showing up in fixtures, unwanted. NYS & NYC code (ICC-based) wants one full sized stack from the base of the Main horizontal building house drain FULL size through to the Roof vent (outside air).  This is where we start our Vent Stack in multi-story Buildings.  

If you can, I'd drop a Dedicated 3" Vented Waste Stack for the Clothes washer and tie it in as far away from the base of the drop in the basement as possible, 40 Pipe diameters is good. Good Luck Mad Dog 🐕 

Zman

Danny Scully said:

How close is the washing machine to the lav @Zman ? 

It’s the next room over. About 8’ way

Danny Scully

Putting it next to the lav isn’t feasible, right @Zman?

kcopp

I was under the impression that clothes washers we only supposed to be tied into the building drain.
Cant tie into a wet vent or dry vent or bathroom group....
Yes I can see that would be a real pain in that situation.

Zman

Danny Scully said:

Putting it next to the lav isn’t feasible, right @Zman?

Correct

Danny Scully

@Zman, It’s also not near that 2” or 3” waste line right? How feasible is it to actually run another line? 

Mad Dog_2

In NYS, the only real rules on it that matter is that The Branch drain is connected to a Minimum of a 3" Drain OR you can dump in to a Slop Sink. So, I always use a 2" Washing Machine Standpipe, 2" Trap and as soon as I can get it in  to a 3" Drain.  
I wouldn't really call that Text book "Wet Venting" dumping in to a Vent stack.
Wet venting is using the waste of an adjacent fixture as a vent for said fixture...i.e., using the vertical Lavatory waste as the  "Wet"  Vent for the Bathtub 🛀 .  Mad dog 🐕 

Intplm.

Years ago, the way the plumber hooked the washing machine. It probably would have been fine. The pumps back then were not as powerful as much as they are nowadays.
Appliance manufacturers have been making pumps with a lot more pumping capacity creating more lift and velocity.

hot_rod

Is it code compliant?
Or will it work safely?
Which answer do you want

Search around and you can find the code and the also interpretation version of the code. Which better explains the intent. Interpretation is in blue print, typically.


https://forms.iapmo.org/email_marketing/codespotlight/2020/june4.htm

Mad Dog_2

Don't rip rhe build apart over this...Mad Dog 🐕