Plumbing problem -Auto Vent?

[Junior]

I had a washer & dryer relocated to my basement several months ago and just recently have had a flooding problem. The washer drain tees into an existing kitchen sink drain, coming from the floor above. We rarley fill the kitchen sink because we have a dishwasher, but the wife gave the dogs a bath, filling then draining the sink. This caused water to pour out of the washing machine drain in the basement below. I was wondering if an automatic vent placed somewhere in line could solve this problem. I think the sink itself is vented because I can see a vent pipe coming out of the roof in it's general location. If an auto vent might help, where would be a good location for installation? The washing machine has no problem draining. The problem only occurs when draining a full kitchen sink.

I have created a crude illustration of the situation here:

Thanks for any advice.

[Paul Franklin]

I was going to say to snake the line, that your drain was partially blocked, but that doesn't jibe with the washer draining fine.

So, SWAG no. 2. It's possible the glug of water (technical term) from the sink is temporarily pressurizing the line enough to blow the water in the washer leg trap out the washer stand pipe. If that's the case, an autovent won't help...it won't open on pressure, only on suction. A real vent would help though. Is it just a little water that leaks out? Try adding food coloring to the water in the sink and see if the water that comes out is clear or colored. If it's the trap water, it will be clear.

HTH,

Paul

[DanG]

An additional vent won't help. A check valve in the washing machine line would.

[Secretia Green]

Thank you for the response. Alot of water is spouting out, definetly more than just the contents of the washer's trap.......

[Junior]

I wondered about that myself, wasn't sure if that was common/proper. Is there a particular type of valve I should locate? Are such valves available at the big box stores? The lines are standard 2" black PVC.

Thank you for the response.

[jim]

Put a check valve on the washer and make sure the stand pipe is 4 ft high also uses a y to enter the other pipe what size is the other pipe from sink and washer ,are you using a single sink

[Joe]

here:

The washer needs a vent well below the wye inlet to the main line. Since air is more easly displaced than water, the trap at the washer will then hold as it should and the massive sink discharge will meekly flow down the line. You may want to check your sink vent for blockage, if indeed tthe vent you see is connected to the sink. Your plumbing system already has one error, so there may be another involving the sink. HTH

Joe

[Robert Allison]

There is no such thing as standard black PVC. There is black ABS.

I second the installation of the check valve. BUT, I would snake out the drain first. It is most likely that you have a restriction in the drain line which can allow for the slow discharge of water, but backs up when the line is flooded such as from the sink being drained. A standard 2" drain should be able to easily handle a sink draining. Also, check the vents to make sure that they are not stopped up, but I doubt that they are. It is most likely a restriction in the drain.

An auto vent would not help at all as the opening of the washing machine drain line is a vent in itself.

[Steve Barker LT]

You're downstream is partly plugged i would say. To back up, there must be a restriction down past your clean out in your drawing.

s

[Steve Barker LT]

Yes, you should be able to get a 2" sump pump check valve and do the job.

s

[John]

Install a check valve in your horizotal drain line that services your washer.