New LG washer in 1995 built home. Installer ran drain test and said drain over flowed indicating a possible clogged drain. I used DRANO and hot water followed by inserting a garden hose with a high pressure nozzle. The water flowed thru with no problem. Ran another drain test and the water expelled from the machine fine until the spin rate increased at which time the water backed up (syphoned) and out into the laundry floor. It appears that the washer is expelling water faster than the drain can process the inflow. Any ideas on how to resolve this problem?

discharge the washer into a laundry 'tray sink' which will act as a 'reservoir/buffer' for the hi flow discharge of a 'modern' he machine

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

Sometimes reworking the existing drain line will enable a 1 1/2 in line to handle the high flow from a current machine. Increasing the height of the standpipe also helps.

I had a customer with the laundry drain overflowing after she bought a new washer. This was 1 1/2 in copper drain which is even more restrictive than 1 1/2 ABS or PVC. I changed the fitting at the stack from a tee to a wye (drain was vented) and also increased the height of the standpipe and there were no more overflows.