What is minimum distance between top of washer standpipe and main drain line?

[Maschi]

I'm installing a clothes washer in a basement. There's a 2" drain line running in the wall at about 43" above the basement floor. What is the minimum distance needed between the top of the standpipe and the top of the 2" drain line? Or does the trap at the bottom of the standpipe need to be above the main drain line? I'm planning on using an 18" (x 2") standpipe. I figure the machine should be able to pump up to the top of the standpipe, but want to make it as low as possible. Thanks.

 

[Jadnashua]

Depends on what code you are supposed to be using, but one of them calls for the standpipe to be no less than 30" and no more than 48" above the height of the floor, and the trap to be a minimum of 12" above the floor. With the pipe at 43", you wouldn't have enough height for the standpipe and still be within specs since it reference is the floor, not the height of the drain line.

You also need to vent the line to ensure other stuff draining doesn't siphon that trap dry in between uses.