# Automatic Clothes Washer Waste Connection



## jar546 (Jul 17, 2020)

There seems to be a big difference between Commercial and Residential requirements for an Automatic Clothes Washing Machine (comm) and a Clothes Washing Machine (res).

While the plumbing code for commercial (406.2) requires that: 

The waste from an automatic clothes washer shall discharge through an air break into a standpipe in accordance with Section 802.3.3 or into a laundry sink. The trap and fixture drain for an automatic clothes washer standpipe shall be not less than 2 inches (51 mm) in diameter. The fixture drain for the standpipe serving an automatic clothes washer shall connect to a 3-inch (76 mm) or larger diameter fixture branch or stack. Automatic clothes washers that discharge by gravity shall be permitted to drain to a waste receptor or an approved trench drain.

Meanwhile, the residential code simply states:

The discharge from a clothes washing machine shall be through an air break.

The commercial code has more requirements since you must connect the _fixture drain _to a 3" or larger _fixture branch _or _stack.  _The residential code does not have that requirement.

Do you think this is unnecessary language due to standard practices?  How often do you see a 2" fixture drain going into another 2" or 2-1/2" branch anyway?


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## steveray (Jul 17, 2020)

I fail it all the time....


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## Keystone (Jul 17, 2020)

I’d say the transition into a 3” branch or stack for commercial is necessary, commercial usage is typically  higher hence the use of commercial equipment vs residential equipment.   I can also assume the discharge volume of a commercial washer is greater vs residential..


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## jar546 (Jul 17, 2020)

So how long is too long for a fixture drain before you make them change it over to 3"?


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## Min Lim (Nov 15, 2020)

jar546 said:


> So how long is too long for a fixture drain before you make them change it over to 3"?


CPC (or UPC) 804.1 - Trap must be not more than 18" above the floor, and shall not be installed below the floor.  It won't allow a long distance if you consider a pipe slope for drain.


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