combines washer drain/water softener

[Jeff409]

I am hooking up 2 water heaters and a new water softener. I have 24" water heater pans under each appliance. They have 1" drains, which I have combined together to drain into the existing washer machine drain. ( 1 1/2" existing drain ) I have installed a 1 1/2" drain 18" tall for the water softener to discharge into the existing washer drain as well.
I have a 1 1/2" existing drain for the washer machine discharge hose that is about 36" above the floor, roughly 36" long running horizontial with the wall. The problem I am having is when the washer machine pumps out after the soap cycle, I am getting soap suds backing up in the pipe stand as well as the drains from the water heater pans. I have P traps on both lines draining into the existing line. I am wondering that if the washer drain is too high and the speed of the water coming down the 36" pipe is forcing air back into the new drains. With the suds being lighter, maybe the air is forcing the the first thing it comes to back up. The drain that is under the floor exits from the house at a fairly good drop. So I need suggestions on what to change. Do I need to make the washer drain exit after the 2 new drains? Thanks

[HayZee518]

As water seeks it own level, having the secondary drain lower in the line than the first sure it'll back up! Even it its got a sanitary tee - it'll do the same thing. If they were of equal distance from the drain it may work. If you could use a branch tee-wye cut in before the tub trap it might work better. they'd share a common trap.

[LazyPup]

I see numerous problems and code violations in this design which I have listed below.

First, there is no mention of the T&P (Temperature & Pressure relief valve) discharge lines on the water heaters. I am assuming that they are probably set up to discharge into the water heater pans.

T&P DISCHARGE LINES:
The T&P discahrge line diameter must equal the T&P discharge port diameter and must run undiminished in size to the point of termination.

The code specifically prohibits T&P valves discharging into the pans.

T&P discharge lines must terminate outside of the building at least 6 inches above grade or into an indirect waste.

Each water heater is required to have a separate T&P discharge line, they may not be combined.

T&P discharge lines may not be trapped.

There can be no valves or threads on the discharge end of the line.

WATER HEATER DRIP PANS:
Water heater pans are required if the water heater is installed in an attic or over wood that can be damaged by water leakage.

Water heater drip pans are required to terminate outdoors at least 6 inches above grade or by means of an indirect waste.

Water heater drip pan drain lines may not be trapped.

WATER SOFTENER DRAIN:

An air gap (Minimum of two pipe diameters) is required on water treatment drains.

WASHING MACHINE STANDPIPE:

Minimum trap diameter is 2"
The washing machine standpipe must be a minimum of 18inch high but not more than 42inches high under the International Residential Code-IRC (30 inches high under the Uniform Plumbing Code-UPC)

NOTE: INDIRECT WASTE CONNECTION- A line required to be connected by means of an indirect waste may discharge into a sink, floor drain or other receptor providing the lowest point of the discharge line must remain a minimum of two (2) pipe diameters above the receptor.--I.E. an 1 1/2 line would have to terminate a minimum of 3 inches above the highest flood level rim of the receptor.