Bathtub Drain Sizing

[Cobalt]

My ceiling is open and I have the opportunity to improve some plumbing.

My bath empties into a 1 1/2" P-trap and connects into a 2" branch. (see diagram)

Would there be an advantage to re-plump the highlit section of 11/2" drain pipe to 2" after the 1 1/2" P-trap to the 2" Tee? Would the drain flow faster?

Thanks

 

[WorthFlorida]

Tubs drain slow because of the design of the drain shoe to the trap and the type of stopper used. All tubs are 1.5". It won't hurt to increase the drain line since you have access but also replace the trap with a 2". If your tub is now draining slow, somewhere there could be a clog usually from hair. BTW, all traps below the floor level, bath tubs and showers must have cemented joints. No slip joints except at the vertical tub drain pipe depending on the material it is made of. Some are cemented, other are threaded.

 

[Sponsor]

 

[Cobalt]

thanks for your informative reply. i will check for clogs

i find changing the P trap a little daunting because of the space. if i just changed the section of pipe do you think would it make a difference or am i just wasting my time?

 

[John Gayewski]

Your drain should change as you have it drawn. That would be what code requires here. As far as how much improvement? Not sure

 

[Jeff H Young]

I dont think changing trap arm size but leaving the p trap at 1 1/2" will help. but my code requires a 2 inch trap arm and p trap when over 42" long