Adjusting washer standpipe position

[DanFL]

In order to keep my washer standpipe and trap in a single stud bay and meet the minimum trap arm length requirement, can I do what is shown in the diagram? It would be preferable to shift the drain position instead of the standpipe, but not sure if that's allowed (IPC).

 

[Reach4]

Yes, but two 22.5s may be plenty, instead of two 45s.

Street 22.5 shown.

Traps don't usually have that long sweep exiting the U. That pipe glued between the trap and the santee does not have to be very long at all.

Picture from https://terrylove.com/forums/index.php?threads/is-this-steep-slope-ok-on-the-main-drain-line.90212/

 

[Sponsor]

 

[Terry]

Change of direction on the vertical is fine. Don't forget a cleanout.

Typical washer rough in new construction, two inlets on the drain, one for the condensation off the furnace.

The dryer box is nice too, and the hammer arrestors for the water supply on the washer.

 

[Jeff H Young]

both illustrations are fine. 2 times diametor is not the minimum length of trap arm in upc but minimum distance edge of vent to wier of trap there is a differance your piece can be less than 4 inches long. if its castiron it can go fitting to fitting plastic might need a small gap between fittings

 

[Reach4]

both illustrations are fine. 2 times diametor is not the minimum length of trap arm in upc but minimum distance edge of vent to wier of trap there is a difference your piece can be less than 4 inches long. if its castiron it can go fitting to fitting plastic might need a small gap between fittings

If I get to wandering around stores again, I might hold a 2-inch plastic P-trap up against a plastic santee, and measure how long the resulting pipe-to-weir distance is. If I call that distance D, the minimum pipe showing between fittings will be (4-D) inches.

That may differ between PVC and ABS fittings. The Charlotte catalog does not provide the socket depth for traps and santees. And for a coupling, there is a small difference for ABS and PVC.

 

[wwhitney]

Standard socket depth is 3/4" for 2" fittings, as it says at the beginning of the Charlotte catalog (page 12 on my version). 2" san-tee shows a vertical center-line to base of socket measurement of 2-5/16"; the p-trap diagram doesn't give a measurement from weir to base of socket, so it may be as low as 0" but I think it has to be positive, so I'm going to call it 3/16".

That means hub to hub p-trap to san-tee would give 4" from vent center-line to weir. If we assume the "two diameters" rule refers to nominal diameter and is measured from the edge of the interior of the vent, that would be 3" for hub to hub. So at least 1" of plastic pipe should be showing between the hubs for a 2" p-trap to 2" san-tee in plastic.

Cheers, Wayne

 

[Reach4]

I attempted to put numbers to this. Dimension F would be the shortest the pipe (nipple) between fixtures would be to avoid a crown vent, assuming 4 inch (2x nominal pipe diameter) weir to pipe.
Cut your pipe to the longer of dimension F or that which will let the pipe fully seat in the two sockets.

If the sockets were both 0.75 each, a crown vent would be possible if the nipple is shorter than 2.711 inches. Let's make that 2.75 and have a bit of margin.

 

[wwhitney]

I think you pulled the wrong dimension from the Charlotte catalog, A should be 2-5/16" for both PVC and ABS. And the socket hub depth is 3/4".

Cheers, Wayne

 

[Reach4]

I think you pulled the wrong dimension from the Charlotte catalog, A should be 2-5/16" for both PVC and ABS. And the socket hub depth is 3/4".

Cheers, Wayne

Thanks. I revised a few times.

 

[Jeff H Young]

Ok that looks reasonable reach 4 working in stud bay a 2 3/4 inch trap arm can definately be a big differance than 4 inches and save you offsets or just some PIA work you dont want to do bunch of extra fittings and pieces. never seen anything in a chart but held the fittings up and kind of guessing. Its a minor detail that gets overlooked but obviously it dosent need to be a 4 inch piece .
By the same rule a 2 inch trap arm cannot be 5 foot long in upc code but shorter by I guess 1.289" dont think Ive realy pushed the envelope on that but if your over 5 foot by more than a inch 2 someone going to say something if theres any plumbers or a real inspector around