What causes the slow drain?

[froddan]

I recently changed the plumbing for a tub-shower from the old galvanized pipes to ABS pipes. I changed the entire drain from the Overflow to P-trap, vent connection and past the sinks.
Everything seems fine, I pretty much configured it in the same way the old pipes had been, but it drains pretty slowly.

I used 1 1/2 inch pipes, same as before, and I think there is enough slope to the entire drain.
There are certainly no clogs as the pipes are new.

I did a test by filling a 5 gallon bucket with water, poured it into the tub, and it took 62 seconds for it to completely drain, vs only 28 seconds fror the 5 gallons to drain from my kitchen sink, which has a 1 1/4 inch pipe.

It drains evenly slow (if that makes sense).
I removed the overflow puck to see if that blocked anything, but it didn't change it at all.
The only thing I could guess would be if it is clogged further down the pipe.
Would "not enough slope" create this problem?
Could it be a vent issue? There is a vent about a foot from the tub.

Any suggestions would help!

Thank you!

[LazyPup]

First off, let me make a clarification. Your kitchen sink pipe is not a 1-1/4” pipe; it is a 1-1/2” pipe the same as the tub drain. The only drain in a residential structure that is permitted to be 1-1/4” is the lavatory drain, however the code will allow us to increase a trap or drain by one nominal trade size, therefore most plumbers today opt to make the lavatory drain lines 1-1/2” in order to eliminate the need of maintaining a complete inventory of 1-1/4” pipe and fittings for the limited use of a lavatory drain.

I can think of a number of possibilities that might be causing your problem.

If you have a standard lever type drain stopper the linkage from the lever to the stopper may be too long and the stopper is not lifting completely above the side opening of the Waste & Overflow tee. If you remove the overflow cover and examine the drain linkage you will see that it is adjustable.

If you have a lift and turn or toe-tap stopper, the stopper may not be lifting high enough to allow full flow to the drain. To test first pour a bucket of water and time it as you did before, then remove the stopper and pour another bucket of water to see if you get the same results.

QUOTE” I pretty much configured it in the same way the old pipes had been, but it drains pretty slowly.”

For gravity flow pitch is very critical. All pipes 3” or less in diameter MUST HAVE a minimum of ¼ “ per foot pitch.

All connections to a horizontal drain line MUST BE made by means of a Wye or Wye & 1/8 bend. Sanitary Tee’s are prohibited on a horizontal line.

[froddan]

Lazypup,

Thanks for your answer.
First of all, you are right about the kitchen pipe, it is 1.5 inch.

I have completely removed the stopper to see if that caused the problem in the tub, but that was not the case. I poured the 5 gallons - and the same problem occurs.

What really bugs me is that before I changed the galv pipes to ABS, it drained ok, with somewhat rusty and blocked pipes. (I realized this after I cut the galv pipe and saw all the rust and junk in there).
The only change I made was to put the new P-trap about 2 inches higher up towards the tub drain, which should create some more slope and therefore improve drainage. Other than that, everything is put together in the same manner as before, but with clean new pipes.
Would the location of the P-trap affect drainage for a tub?
For example, if the vertical drainpipe under the tub only extends 2 inches down before it reaches the P-trap, vs if the vertical pipe is longer before it reaches the P-trap?

The vent is the same as before- located about 1 foot away from the tub after the P-trap.

I guess there could have been some debris that got stuck in the pipe that I didn't see.

Would it be wise to snake it with a small auger? Is there one that would make it through a 1.5 inch pipe and P-trap?

Thanks again!!!

[LazyPup]

The illustration shows the tub vent in the walk space in front of the tub. How were you able to put a vertical vent riser there?

[froddan]

I guess I am not very good at drawing...)
There is a wall right by the head of the tub, and the vent is in that wall, going vertically. Sorry about the confusion in the drawing.
The red dot should be moved slightly...but the vent is currently less than a foot away from the P-trap, going vertically up into the attic where it makes a slight bend and then up through the roof.

Both the vent and the drain is 1 1/2 inches

[LazyPup]

I suspect that you have a bottleneck at the 90 deg turn by the lavatory but i would need to see the layout to be sure. Would it be possible to post a picture of the pipe layout at that corner?

[froddan]

The turn by the lavatory is a long sweep of two 45* turns, but it is definitely possible that this is where the bottle neck is.
I can't take a picuture of it at this time as the ceiling has been closed up after my repair.
To avoid this turn, would it be a better idea to have the tub drain turn 45* earlier and meet up with the sink closer to the main stack?

[froddan]

Fixed it!
The problem was the overflow tube...it was too small and the connection in the cross was very tiny. Unbelievable that they can manufacture and sell that kind of stuff.
Thanks for all the help!