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The very popular general plumbing, toilets, sinks, faucets, pump problems, questions and answers discussion Forum
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Author:
sum (FL)
I need to tie a laundry sink and a washing machine drain into a 3" stack.
I intend to place the laundry sink 1-1/2" trap arm at 12.5" above the concrete floor, which will make it 12" above the finished floor after the tiles are laid.
Above the laundry sink sanitary tee, I will add another sanitary tee for the washing machine trap arm, probably about 6" above (unless I use a street san-tee to lower it some), so that will make the washing machine trap arm at 18" above finished floor.
Since the washing machine stand pipe is 18" minimum in length, that would mean the top of the stand pipe will be about 36" above finished floor.
Is the top of the stand pipe 36" above the floor too high to "hook" the flexible line from the washing machine into? 36" happens to be the height of my washer so it sounds ok.
If it is too high then I will reverse the two san-tees but if I put the washing machine line below the bottom of the trap may touch the bottom plate.
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Author:
steve (CA)
No, it's not too high. I've seen a manufacturer specification for a washer before, that allowed the drain to be as high 7'.
I just checked Whirpool website and found an 8' maximum drain height.
Edited 1 times.
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Author:
packy
the laundry sink is usually a pretty deep sink so the drain must be roughed in low. 12" off finished floor is about right.
both will need to be vented individually but the vents can be tied together 6" above the washer stand pipe.
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Author:
sum (FL)
7' wow, that means the pipe could be all the way up near the ceiling? I know it's pressurized but had no idea it could be this high.
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Author:
hj
A 3" stack implies that it is the drain for some higher fixtures, which means that you CANNOT just insert the tees and connect the sink or washer drain. There is additional vent piping which has to be considered, and an AAV is not sufficient for that location.
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Author:
sum (FL)
Since my laundry sink is only about 36" from the 3" stack, and the washing machine is right next to it, I am not going to tie them back together but instead each will have a trap arm that goes to the 3" stack, I will just have two sanitary tees one above the other, one being a 3x3x3x2 for the washing machine (and a CO) and the other 3x3x1-1/2 for the laundry sink.
I was just deciding which is goes below and which one goes above. Seems the laundry sink needs to go below.
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Author:
sum (FL)
hj there is no higher fixture, the fixture is the washing machine and that is it. It is single story and this is the most upstream point hence it was required to be 3". That stack serves to vent only the washing machine in the past and I am adding a laundry sink to it, nothing more.
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Author:
dlh (TX)
you need to reverse them anyway since the washer is considered a major fixture and you can not dump a major over a minor with a wet vent
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PLUMBERS "Protecting The Health Of The Nation"
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Author:
sum (FL)
dlh are you saying this is no good because if the washing machine dumps at a high rate of speed to that flows saturates in the entire 3" pipe it will suck the water out of the 1.5" lav line and break the trap seal?
The san tees are only several inches apart and it's a 3" line. Can it happen?
If I have to reverse the two, and keep the laundry sink at 12", the washing machine line will have to be very low. I am not sure I have enough room for that 2" p-trap as it may be in the way of the bottom plate.
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Author:
hj
Theoretically possible, but not likely with a 3" vent.
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Author:
dlh (TX)
in theory yes
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PLUMBERS "Protecting The Health Of The Nation"
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Author:
North Carolina Plumber (NC)
The tee for the washing machine drain needs to be closest to the floor, then the tee for the laundry sink. Here in NC the minimum standpipe for washing machines is 24".
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Author:
waukeshaplumbing (WI)
they can be vented together with a vertical wet vent...
i run my washerboxes 42" off the floor, so your low in my opinion...id go 42-48 high
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Author:
waukeshaplumbing (WI)
your drawing is code legal in WI, but would need a 3" cleanout T
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Author:
sum (FL)
The top san tee actually would be a 3x3x3x2, where the 3" branch would be a CO opening facing towards the other side (the garage).
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Author:
LemonPlumber (FL)
You still cannot drop the washing machine past the lessor lt drain.Unless you revent the lt.It may work but may very well siphon the lt trap dry.And effect your health!If you feel stuck with this configuration change the lt drain through the trap to three inch.At least you will legally poison your family.Sum ???:?Would you flush a toilet past this lt drain?The washing machine has a much better chance of pulling the trap dry!!!!!
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Good Luck. Insulate your hot piping, although costly, it will pay you back every day.
Edited 1 times.
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Author:
sum (FL)
Lemon, but the 2" is dumping straight down into a 3", with the laundry tub drain only a few inches below, can it really create a negative pressure to siphon off water in the trap from the laundry tub?
May be it's easier if I only tie the laundry tub in and forget about the washing machine, I can hook the washing machine discharge pipe to the edge of the tub, and use a 2" line instead of the 1-1/2".
or get a wall mount laundry tub that I can mount higher then the 12", to clear room for the washing machine drain to go below it.
Right now it will not fit because on the face of the concrete wall, is a series of 2x3 studs. They are not structural, just a way to fur out the wall to accmmodate electrical boxes, pipes, conduits etc...so, I have a bottom plate 2x3 at the base, the p-trap of the washing machine drain wants to go lower than the top of the bottom plate.
Edited 1 times.
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Author:
LemonPlumber (FL)
I might try coming off the stack lower with a wye fitting then another wye on top of that .It may be low enough to allow you to get the lt on top of the wm discharge .
Uploaded with ImageShack.usI would prefer this.
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Good Luck. Insulate your hot piping, although costly, it will pay you back every day.
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