Washing Machine Drain

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jpm6621

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Does a washing machine drain need a vent when its tapped into the main stack? Or does the vent of the stack act as a vent for the washing machine drain too?

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If there are other fixtures on the stack above it, then in most cases "Yes" it does need a vent.

With more detailed information as to what fixtures drain into the stack and where, I could possibly be of more help.
 
Yeah if there's a toilet draining in the same stack above your laundry then yes you need to vent the laundry. Toilet has to be the lowest connected fixture on a wet vent (at least that's what I was taught in school)
 
how did you seal the pvc pipe in the cast iron hub , with silcone ?
 
PVC Pipe into Hub is sealed with oakum. I use to have Hercules Plastic Seal around that, but i have changed some things and have not got any more yet. The pipe you seein the picture is the main stack on the left, and the pipe with the drop is for the washer only, it rises up out of the picture where the washer hose hooks in. All of this is in the basement, the picture and the washing machine, so it's all below the toilet b/c thats on the first floor, draining into the main stack above what you see. Does this mean that the drain in my picture needs to vent up and into the main stack above where the toilet drain enters the stack? What about an Air Admittance Valve for the washer drain, just after the trap before it enters the stack? or is that completely wrong?
 
You could do an AAV, ideally a proper vent tied in above flood level rim of the upstairs sink is best but AAV may be the most practical option for you. And yes after the trap but before the tie into the stack is perfect
 
Personally i would have cut off the cast iron hub and used a no-hub band to go from cast iron to abs pipe. I personally dont trust silicone like that. And john is right you should have a clean out some where especially since it is in your basement.
 
Heres another picture. You can see the washer drain and the drain below that goes over to a sink, and that sink has a AAV on it just after the trap. The low spot or "pit" has a lead plug for a cleanout, in which i need to install a sump pump since any outside water that enters the basement ends up here. The sink im talking about use to just drain into that "pit" and there was no plug, letting sewer gas into the house. I installed a plug then tapped into the main stack for the sink. That washing machine machine does't get vented from the main stack? Even being so close?

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It does get vented technically but when you flush the toilet it could siphon the trap out or cause trap blowout, if you had an AAV it would protect that trap. The chances of it actually blowing out is unlikely cause of the Stand pipe but like I said toilet has to be the lowest connected fixture on the wet vent. Whereas now your laundry is.
 
Yup i understand, but im leaving it for now b/c to add an AAV i would have to re-do what i just did since i don't have enough room on the 2" washer drain to cut it and glue a tee in for the AAV. I would have to buy another 3x3x1 1/2 tee for the sink and another 3x3x2 tee for the washer and start over, unless someone has an idea. As you can see in the picture, just after the trap theres only an inch or a little more of pipe but not enough to cut it and glue a new tee for the AAV.
 
Can i use a tee that is 2" on each end but 1 1/2" up to the AAV?
 
Definitely can use a 2x2x1 1/2 up to the AAV. And since its PVC and i haven't worked with PVC much, don't quote me but i believe you can use a Hacksaw blade and make 3 or 4 cuts through the pipe but don't cut the fitting. The basically chip it out. I've done it before with ABS and it worked, so that may be worth a try instead of cutting it all out. Other than that you're SOL. But yeah if it hasn't given you any trouble you could leave it for now I suppose
 
Yes you can but it must be between the stack and the washer trap. It's not totally necessary but I would but the AAV up higher then the stand pipe on the washer trap.

John
 
The AAV's i have bought say to install 6" above top of horizontal pipe, so thats how i would install it. If i install above the standpipe like you suggest it would be like 4' up!
 
The fixtures that drain into the line above the washer can choke the washing machine off from venting through the main drain stack. Distance from the stack isn't the issue, a vent independant of the main stack is what is needed.
 
The AAV's i have bought say to install 6" above top of horizontal pipe, so thats how i would install it. If i install above the standpipe like you suggest it would be like 4' up!

Like I said it's not necessary. But my reasoning is if the AAV should fail when the washer is draining it could spill out through the AAV if it is lower then the stand pipe.

John
 
johnjh2o said:
Like I said it's not necessary. But my reasoning is if the AAV should fail when the washer is draining it could spill out through the AAV if it is lower then the stand pipe.

John

I agree with John. It does kinda look goofy on laundry stand pipes but its a good practice. That's like tying in any vent, you do it above flood level rim of the fixture it serves so if the drain backs up, the vent cannot serve as a drain. But again you don't have to with the AAV if you don't want to
 
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