Re: Trap type and diameter for clothes washer...
Posted by hj on April 04, 2004 at 22:46:37:
In response to Re: Trap type and diameter for clothes washer...
: Folks:
Get a plumber. A "P" trap and an "S" trap, if you really have one, have the same "lift" dimension. The difference between the two is how the pipe after the "bend" is arranged. Your description is very convoluted and appears to be making a simple task into a major project.

: My clothes washer is backing up occasionally and spilling from the top of the drain pipe. Since I know nothing about plumbing, I hope you can help... My questions are as follows:

: - Should I replace the S trap with a P trap
: - Can I replace the 1.5" trap and pipe with 2" or larger diameter (is there a maximum or recommended size).

: The top of the 1.5" washer drain pipe is around 4' from the floor which connects down to a 1.5" diameter S trap which is around 18" from the floor. This connects directly to a 90� connector which then goes to a short horizontal run of 1.5" pipe (only 8-10" long) to a Tee connector in a 1.5" vent stack. I am thinking that the extra loop in the S trap makes it difficult for the rush of water to get through when the washer starts to drain. I think a P trap would need less force required to get the water over to the vent stack, as it wouldn't have to climb the extra 3-4" that the S trap has. Can I use a P trap on a washer connection? or will suction (back-pressure)cause a P trap to clear out when the pipe drains?

: I am thinking of replacing the 1.5" T in the vent line with a 2" one and using a section of 2" pipe with reducers above and below a 2-3 foot length. That would then allow me to use a 2" diameter trap and pipe which would carry more water from the washer. I would be switching to a 2" P trap (from a 1.5" S trap) at the same time which I assume should make the water run much faster/easier. Also, since the vertical pipe below the T connection is then 2", it should be able to buffer up a gallon or so more water in case my 50 year old buried drains are slow...

: Any ideas you might have are greatly appreciated and thanks in advance.

: I even thought of replacing the 1.5" Tee with a 2" cleanout and use a 45� connector to go horizontal to the new trap so the falling water leaving the trap would already be pointing downwards when it goes into the vent stack, I am not sure if that is approved in the local code and/or if it makes much sense. I just guessed that venting air is easier than water and a 90� T would restrict water flow more than a downward pointing 45� connector would. Since the total weight of the water plus piping in this system is only around 5 pounds, the 2" Tee or 45� should have no problem.

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