Leak only when shower is used a very long time


Old 08-08-17, 01:31 PM
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Leak only when shower is used a very long time

I hope to get some feedback on a plumbing problem, as well as an issue with my plumber.

When someone takes a veerryyyy long shower in the third floor bath, water drips down the side of the HVAC duct into the basement. I have seen a few trickles and heard the dripping sound when I am downstairs. However, this doesn't happen during short showers or during a bath - only if the shower is running for a very long time.

I have run the following tests:
Ran the bath until full with drain stopped up - no dripping sounds
Drained the tub - no dripping sound
Ran the shower til the tub was full, with drain stopped up - no dripping sound

This is a cast iron bathtub, not a fiberglass shower, so I do not believe there is an issue with the flexing of the floor pan.

I had the shower valve cartridge and handle replaced about 6 months ago (but not the valve behind the wall). That valve is an old Moentrol but the plumber said the valve itself was fine at that time. This seemed to fix the dripping behind the wall during long showers, but is now re-occurring.

I had the plumbers come last week and he looked behind the valve with a camera and didn't see any leak. His conclusion was that there must be a leak in the bathtub drain. The plan was to come back another day with a helper, and rip out drywall under the tub.

They stood me up on that return visit, which was supposed to be today. They have not been very apologetic at all. Meanwhile I have had lingering doubts about this diagnosis and plan, which is sure to be expensive. There is no access panel so they want to rip out the ceiling in my living room to get to the tub drain.

I'm thinking maybe I should switch plumbers to get another opinion. It seems logical that I should try replacing the tub spout/diverter and shower arm first. I have read that you can get leaks behind the wall if there is not a good seal behind either fixture. Since they are both original to the house (1974) it seems sensible to try replacing those first.

Thoughts? Thnk you very much!
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Old 08-08-17, 02:26 PM
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I would look at the caulking around the tiles & tub first. Your tests were done with no one in the shower so water wasn't bouncing off anyone. Also look at the plate behind the mixing valve. Pour water on top of it.
Old 08-08-17, 06:19 PM
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I know you have run the bath to fill the tub and probably have eliminated the drain and supply valve. I would also run the shower head for a while to see if there is a leak where it connects to the drop elbow behind the wall. The shower arm is just screwed in and could be a leak there. Next, concentrate on the caulking in the vertical corners of the shower. Many are just grouted when they should be caulked. Then put a level on the tub to see if it has settled and water is drifting toward the outside of the tub when splash hits the deck. Do you have a shower curtain or sliding door?
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