[jetterjet]

The issue is the soap suds, but not water, are overflowing the standpipe. The standpipe has virtually no height as the trap is immediately below where washer hose enters, and then horizontals over to tie into house sewer. This was done because the garage floor level is a couple of feet below the floor level of the house (40 yrs old). I'm thinking of raising the standpipe 12"-18" to give it more capacity above the trap.

How high can I go with the standpipe before the washing machine has problems pumping the water UP that high? (if necessary, I can raise the washing machine on a platform a foot or so as well to give the stand pipe even more height)

Would it help to also go oversize on the standpipe, say to 3" or so, to give it more capacity for the soap suds?

I also read what has been said about HE laundry detergent and I'll give that a try too to reduce sudsing.

[Milo Dolezal]

If space permits - and for the optimal performance - you should install stand pipe that is between 30" - 36" tall. Stand pipe and trap should be 2" in diameter.

If you continue experiencing "soap suds" problem than switch to low suds detergent.

[speedball1]

ow high can I go with the standpipe before the washing maching has problems pumping the water UP that high? (if necessary, I can raise the washing machine on a platform a foot or so as well to give the stand pipe even more height)
Would it help to also go oversize on the standpipe, say to 3" or so, to give it more capacity for the soap suds?

Both would work. There would be no problem with the pump if you raised the stand pipe. Also over sizing the stand pipe would give it more volume. But6 the surest way would be to make it a closed system by making the connection between the stand pipe and the washer hose a closed connection. This can be done in several ways. You could install a permanent connection, (see images) with one of these or simply duct tape the hose to the stand pipe. Good luck, Tom