Need to install a compact 2.3 cu.ft. washer/dryer combo next to my kitchen sink and a dishwasher in a multi-unit condo (not a house). Would like to use a double wye or something similar to connect all three fixtures (sink, dishwasher and W/D) to a single trap. Currently, the 2” x1-1/2” sink trap is connected to the main stack about two feet away without a separate vent. Now, I understand that the code says 2” and a standpipe and a trap and a vent but the code allows for huge washers, mine will be outputting max of 12-15 gal. Appreciate any suggestions.



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I'm not sure legally what your code would say about this, probably prohibited and also goes against good plumbing practices. But if you have no other reasonable choice and you are doing the work yourself then I'd say give it a try. It is your place, if it does work ok who's going to know how you did it? If you ever sell the place you can always put it back the way it was, take your washer/dryer combo with you or sell it separately when you move. The risk is that the washer discharge water could backup into the kitchen sink or into the dishwasher.

If the water tries to backup in the kitchen sink you may need to add a reducing insert (like a short copper or pvc tube clamped in place) to the washer discharge hose to reduce its flow. Contrary to popular opinion this does not harm the washer pump, just takes the washer a little longer to empty.



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use the double "Y" but put it on the pipe sticking out of the wall.
one side for kitchen sink and DW. other side for WM trap and standpipe. the straight part of the "Y" takes a cleanout fitting.

Hey stuckinlodi, any time you restrict a pumps designed outflow, I believe you do create stress on the pump motor. Can you share with me where the information regarding this is found. I need to know so I can give good advice to those who trust me. Thanks Stuckinlodi.

When you restrict a pump's output (NOT suction) it 'pushes' less gpm.

less gpm = less work = LESS amperage 'draw'

The ONLY risk is if the pump is 'water cooled' and you throttle TOO much.

Pump basic theory 101.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

"less gpm = less work = LESS amperage 'draw' " Hey Barney, could this not be interpreted as: less gpm could be caused by more friction loss causing more amperage draw. Not disputing your reply but just a consideration.

Hey PlumberLoren, do you drive a vehicle that has a water pump? It circulates coolant water thru the engine block and the heater core. In summer when you select "Max Cool" or "Max A/C" a water valve in the heater hose closes so no water runs thru the heater core. This is one less pathway for the coolant water to flow, ergo you have restricted the water flow. Also, whenever the engine has not warmed up the thermostat is closed so that almost no water flows from the engine block to the radiator so the engine will warm up faster. This means the water pump is pushing against a dead end. Do you really think this harms your vehicle's water pump?

Another example, people with backyard swimming pools adjust the return water nozzles or shut them down to get the water circulating so surface debris is directed toward the skimmer opening. That restricts and reduces the water flow from the pump somewhat, but does not injure the pool's water pump. Pool installers and maintenance people do this all the time.

Many pumps have a designed range of output pressure and flow, they aren't limited to just the max amount of flow. Washing machine pumps are pretty forgiving. For example, at the end of the rinse and wash cycles when the tub is nearly empty the pump is kept running, even though it is cavitating and drawing air. It doesn't hurt them.



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In my state you could not install that washer/dryer that way... kitchen sink shall connect independently to the sanitary drainage system.seen a million installed that way but wouldn't pass inspection.

Washing machine manufacturers state in their I & O manuals that the drain discharge hose cannot be elevated higher than 8' (may be more, may be less). Any distance above the stated maximum does not harm the pump, the pump is simply unable to overcome the friction loss/ head loss above that point. The same applies with restricting the discharge, the pump sees an increase in friction and the gpm is decreased but the pump is not harmed.

curious.. did you figure this situation out?

I have a similar scenario and would like to know if this is possible.

Thanks