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Old 07-20-2010, 09:26 PM   #1
nickb7
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Default Washing machine plumbing

I have a washing machine in my basement. The existing drain line is higher than the machine.

The existing drain line is 2" ABS pipe mounted on the wall 5 feet above the floor and behind the washer. The drain line is a horizontal 2" line that connects to a 2" P-trap with 12" long vertcal riser. The flexible drain hose from the machine is hooked over the top the riser. 5 feet from the P-trap the horizontal 2" pipe connects to a vertical vent pipe that drops immediately (6"drop) into the 4" building sewer. The building sewer exists through the foundation wall and connects to the side sewer.

The riser top overflowed recently, probably due to some lint build up, and this caused me to review the situation. It seems to me that the short riser is a weak point in my drain. It really can't be lengthened because the pump is already pumping up to a height of 6 feet. I was thinking of making a closed connection.

What I was thinking of doing was sawing a few inches off the riser and fitting a wye piece. I would connect the flex hose to the branch using a nipple and clamp, and whatever reducers. To the top of the wye I was going to connect an air admitance valve. The valve is to break the suction if it ever gets into a syhpon back into the washer mode.

Does this sound like it will work? Also I am a little worried about forcing the water out of the P-trap - do you think that could happen?



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Old 07-20-2010, 10:23 PM   #2
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The description is somewhat confusing without pictures but I do get the gist of the situation.

I would recommend eliminating the wye, and find the coupling I once used with great success. This coupling was pliable gray rubber, fits the rim of the riser, and sealed with a hose clamp. Your washer discharge line is inserted onto the side of this coupling, which is also secured with a hose clamp, and it had a built in air valve on top of it. A Sears appliance repairman provided it to me, and said with the amount of pressure my new washer was emitting, this was the only way to prevent backflowing.

I'm sorry for my lousy description but hope you get somewhat of an idea. If you have a Sears Appliance Center close to you, you may have luck picking one up.



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Old 07-20-2010, 10:47 PM   #3
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Is the air valve one-way? Can water spew out through it?

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Old 07-21-2010, 12:48 AM   #4
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If I understand what you guys are discussing correctly, there is no flood level established for the washing machine drain, and any such arrangement would create the potential for backflow.

I could have completely the wrong idea, but my Spidey Senses are going off right now.

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Old 07-21-2010, 12:56 AM   #5
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Quote:
Originally Posted by nickb7 View Post
Is the air valve one-way? Can water spew out through it?
Yes, it's a one way valve. Also, keep in mind what Phish is saying. My home (one story only) is conventionally set, with the flood level well below the pipe, so please take this into consideration.
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Old 07-21-2010, 10:38 AM   #6
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You are correct Phish. By making it a closed system you are connecting the water supply of the house to the sewer.

The "Air Break", is a necessary design for backflow prevention, not letting air into the line. Your existing vent is already enough for that.

Secondly, how will you know if something is wrong in the future?

Thirdly, what happens when (not if, we are all susceptible) your sewer backs up? Now the poo can be forced into your clothes washer.

Have you read the manual on the washer to find out the maximum vertical distance of the pumps capacity. Six feet is high, but I'm betting you could go another foot or two. And add a lint trap to that thing.

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Old 07-21-2010, 07:28 PM   #7
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Thanks guys for the helpful responses.

havasu: the fitting that you are describing sounds like what I am trying to manufacture out of fittings. Sounds good. Seems like I am reinventing the wheel maybe.

phish: Yes the situation is not good but it is an existing condition and I cannot get arouind it. If I wanted to really fix it to code, and make it fail safe, I woulld move the waser upstairs, rebuild the laundary up there and cap off everything downstairs. Are you thinking that I should leave the drain connection open and let the sewer overflow over the top of the standpipe rather than into the washer? How about a check valve on the flex drain line? (the lint would probably mess it up, right?)

Reedwalker: Not sure what you mean by connecting the water supply to the sewer. Do you mean there is a potential for crossconnection and contamination of the water supply? Seems that would make the havasu fitting illegal. The water supply pipes are above the washer, I dont think we will get a suction into the water pipes under any circumstances.
Yes about he air-break, that was my intention with the AAV.
Good thought about the lint trap.

How about this: what if I cut into the horizontal pipe downstream of the P-trap install a backflow preventor. And a lint trap on top of the riser.

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Old 07-22-2010, 11:29 PM   #8
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Quote:
Originally Posted by nickb7 View Post
The existing drain line is 2" ABS pipe mounted on the wall 5 feet above the floor and behind the washer. The drain line is a horizontal 2" line that connects to a 2" P-trap with 12" long vertcal riser. The flexible drain hose from the machine is hooked over the top the riser. 5 feet from the P-trap the horizontal 2" pipe connects to a vertical vent pipe that drops immediately (6"drop) into the 4" building sewer. The building sewer exists through the foundation wall and connects to the side sewer.
Alright, I had the chance to reread your original post. I think that there might be a solution that will work well without running the risk of cross-connection.

Can you cut out the 4"x 2" fitting that attaches to the main sewer and replace it with one that points to the side? If you can do that, then use a 2" combination wye & 1/8th bend fitting pointing up to reattach the vent to, then add a 2" P trap directly underneath the point that the flexible drain hose drops into the drain line. Use as long as possible a piece of pipe between the P trap and the flexible drain hose. Just those changes right there will give you 18" of drop from the flex line to the P trap As Reedwalker mentioned, check out the specs for your machine to determine how high it can pump the wastewater.

Also, am I understanding you correctly that your current drain line is horizontal until it drops into the P trap? If so, that is very bad design, and it is not surprising that it has backed up. You want the wastewater to drop straight downwards for a distance as soon as it exits the flexline, to build momentum to allow it to flush out through the trap as rapidly as possible.
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Old 07-24-2010, 04:40 AM   #9
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Yes, that would give me a bigger drop to the P-trap and would increase the flow capacity. I am back in town now so I am able to take a picture just so everything is clear. Dont ask me about the duct tape - it was there when I bought the house. Your idea would increase the capacity but I would still have Problem B which is the specter of general sewer back-up,

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Old 07-24-2010, 04:43 AM   #10
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Other end -connection to mainline.



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