What is the correct height for the washing machine drain standpipe or outlet box?
Tuesday, May 21, 2019
Manufacturers specify a height in their installation manual. Whirlpool recommends a minimum of 39” above the floor, and GE has a 30” minimum, except that GE allows the top of the drain pipe opening to be lower if you secure the hose to the back of the machine near the top at a place the manufacturer indicates using a plastic “anti-siphon clip” Both manufacturers have a maximum height recommendation of 96”. Shown below is the Whirlpool diagram and the GE clip.
And the standard height for a washing machine outlet box is 42” in our area. So now you have three different numbers. But the important thing is to get the drain, or the drain hose loop in the case of GE’s anti-siphon clip, above the flood level of the rim of the washer tub. When the drain is below the rim you risk the possibility that the drain hose will suck the water out of the washer tub just as fast as it goes in as the tub fills during the first cycle.
The only code standard is that the top of the standpipe above the trap weir (top level of standing water in the trap below) can’t be less than 18” or or more than 42” according to the Residenital Edition of the Florida Building Code (P2706.1.2) and the International Residential Code. But the trap at the bottom of the standpipe is usually not visible for vertification in a modern house.
Also, see our blog posts What are the most common problems with washing machine installation and maintenance? and What is the maximum length for a washing machine drain hose? and Why are rubber washing machine hoses a safety risk?
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