Mystery Shower Guest- A Plumbing Question

[Dobish]

We recently remodeled our house and put in all new plumbing. we have an upstairs shower stall that has suddenly started dripping when the downstairs bath is running. No other faucets do this in the house, and it is only when the water is running out of the bath spigot, not the shower head.

Thoughts on what this could be? it doesn't get used very often....

 

[begreen]

Sounds like a pressure drop might be causing a seal to weep. We had a crappy Moen faucet that did this sometimes when I was watering outside and then someone flushed the toilet. Has not happened since I replace that faucet with a good ceramic washer model.

Was the upstairs bath plumbed with a 3/4" feed line to upstairs or 1/2"?

 

[Dobish]

Sounds like a pressure drop might be causing a seal to weep. We had a crappy Moen faucet that did this sometimes when I was watering outside and then someone flushed the toilet. Has not happened since I replace that faucet with a good ceramic washer model.

Was the upstairs bath plumbed with a 3/4" feed line to upstairs or 1/2"?

both are 1/2" pex, running through a manifold. We have pretty high water pressure, and I wonder if it just blew a seal due to constant pressure changes. We used to have our whole system running through a dormant water heater (mainly for additional storage), but I removed that since we could not get any water pressure, despite having 120 psi coming into the house.

 

[begreen]

1/2" is pretty restrictive, but 120psi is major pressure. If the pressure drops very quickly as soon as a tap is opened that could indicate a blockage. Pressure can build up high when there's no draw, but drops quickly as soon as a tap is opened.

That said, a friend in Seattle replumbed their whole house in new copper piping. They replaced the water main line coming in too and have great city water pressure. Unfortunately they used 1/2 to feed the upstairs bathroom and have wimpy pressure upstairs if something downstairs is also using water. I plumbed our house with 3/4" to upstairs and even with our moderate house water pressure we get more volume upstairs.

 

[Dobish]

just to be clear, the upstairs shower drips when it is off. When they are both running at the same time, the pressure drops a little when running the bath, but that is mainly due to the on demand hot water heater.

i have a plumber buddy who is going to come take a look at it, but he was baffled by the phone call

 

[Ashful]

just to be clear, the upstairs shower drips when it is off. When they are both running at the same time, the pressure drops a little when running the bath, but that is mainly due to the on demand hot water heater.

i have a plumber buddy who is going to come take a look at it, but he was baffled by the phone call

I was baffled, too... until you reversed your initial statement. ;-)

120 psi is stupid high water pressure for residential. Typical is 50 PSI after borough regulator, or 40 - 60 PSI for a well (although you can sometimes find as high as 75 PSI). If your incoming is 120 PSI, you should be running a regulator.

I’m surprised that any plumber would leave that job with unregulated 120 PSI to the appliances. It’s asking for a failure. Are you SURE you have 120 PSI internal pressure, or is this measured upstream of your manifold?

The fact that it stops dripping when you’re running another appliance indicates that a small drop in pressure will indeed resolve your problem. You will typically see absolute maximum pressure ratings of 80 PSI on residential shower valves. 120 PSI would damn near blow you off your feet, in a first floor shower.

 

[begreen]

The fact that it stops dripping when you’re running another appliance indicates that a small drop in pressure will indeed resolve your problem. You will typically see absolute maximum pressure ratings of 80 PSI on residential shower valves. 120 PSI would damn near blow you off your feet, in a first floor shower.

That's my thinking too. Otherwise...

 

[Dobish]

I was baffled, too... until you reversed your initial statement. ;-)

120 psi is stupid high water pressure for residential. Typical is 50 PSI after borough regulator, or 40 - 60 PSI for a well (although you can sometimes find as high as 75 PSI). If your incoming is 120 PSI, you should be running a regulator.

I’m surprised that any plumber would leave that job with unregulated 120 PSI to the appliances. It’s asking for a failure. Are you SURE you have 120 PSI internal pressure, or is this measured upstream of your manifold?

The fact that it stops dripping when you’re running another appliance indicates that a small drop in pressure will indeed resolve your problem. You will typically see absolute maximum pressure ratings of 80 PSI on residential shower valves. 120 PSI would damn near blow you off your feet, in a first floor shower.

I have one of these that reads 118 coming out of the hose spigot. I have an inline regulator going to the washer, but we were having issues with severe pressure drops with the old water heater setup. Once that was removed, we haven't had any issues. It does not leak at all when nothing is running.

 

[begreen]

What does that gauge read if a tap is opened on the same feed line? If still high, I'd put a whole house regulator on the incoming water.

What is the water source? City or well?

 

[Ashful]

I have one of these that reads 118 coming out of the hose spigot. I have an inline regulator going to the washer, but we were having issues with severe pressure drops with the old water heater setup. Once that was removed, we haven't had any issues. It does not leak at all when nothing is running.
View attachment 217224

Pressure drop indicates a restriction, and while increasing incoming pressure will increase the pressure downstream of the restriction by some amount, it is never the proper fix. Find the restriction, and resolve it, then get that pressure back down to where you’re not destroying your appliances. The borough must run high pressure to account for changes in elevation, and multi-story buildings, but there is not typically any good reason for having 120 psi in a single-family dwelling.

Are you saying you had a restriction on the hot water side only, and it was resolved by removing the water heater? A water heater should not have any effect on the cold water dynamic pressure.

 

[Ashful]

we have an upstairs shower stall that has suddenly started dripping when the downstairs bath is running.

just to be clear, the upstairs shower drips when it is off.

It does not leak at all when nothing is running.

Okay, now I’m confused, again. It seems you’ve gone back and forth 3x, but maybe you’re just changing what “it” is, each time.

Are you saying the upstairs shower only drips when the downstairs bath IS running, or when it IS NOT running?

Either way, while running that crazy high pressure, all bets are off. I’d resolve that, and maybe replace the potentially damaged cartridges, before chasing anything else.

 

[Dobish]

Okay, now I’m confused, again. It seems you’ve gone back and forth 3x, but maybe you’re just changing what “it” is, each time.

"it" is the upstairs shower.

Are you saying the upstairs shower only drips when the downstairs bath IS running, or when it IS NOT running?

upstairs shower only leaks [still turned off] when downstairs bath IS running

Either way, while running that crazy high pressure, all bets are off. I’d resolve that, and maybe replace the potentially damaged cartridges, before chasing anything else.

I agree... the whole plumbing in this place has been all over since we moved in.

City water- whole house regulator on order. will be tearing the cartridges apart shortly. I haven't tried testing the pressure with the tap wide open. I will do that tonight.

 

[Dobish]

The borough must run high pressure to account for changes in elevation, and multi-story buildings, but there is not typically any good reason for having 120 psi in a single-family dwelling.

We are at the top of the hill, very close to where it starts.... a few blocks south, it is significantly less.

Are you saying you had a restriction on the hot water side only, and it was resolved by removing the water heater? A water heater should not have any effect on the cold water dynamic pressure.

the way that the previous plumber (who left an unfinished job) had it set up was to split the line off of the main, running 1 line to the cold water manifold/shutoff and another into a water heater tank that was being utilized as a storage tank. The on demand water heater was pulling water from the "storage tank". Because there was no pump, and the split was basically off of the main, it was constantly filling the water tank. When the second plumber came in, he realized that the water heater "storage" tank was causing a lot of the issues.

 

[semipro]

Strange.
It looks like your PEX is run in a home-run configuration with shut-off valves at the manifold. Just for grins you could shut off the cold water supply valve to the upstairs bath to see if that makes a difference. I get that it should but... I'm not sure how your hot water to the upstairs bath is run but if it has a separate shutoff valve you could try that also.

My guess is the what BeGreen said; you have a bad faucet upstairs and somehow the pressure drop is resulting in leakage at the valve. I can't help but wonder if this isn't related to the anti-scald circuitry in the valve (assuming it has that). The really strange thing is that it only happens when you use the shower faucet downstairs rather than the shower head.

Edit: I also agree your pressure needs reducing. Many time municipal water supply pressures are wholly dependent upon the height of water in the storage tower and system demand. They have to design the system so that the farthest and highest houses still get adequate pressure. This often results in excessive pressure at house that are closer/lower.

 

[zrock]

You may want to check but most hot water tanks that i have ever seen have a label on them that state 100psi max.

 

[Dobish]

You may want to check but most hot water tanks that i have ever seen have a label on them that state 100psi max.

don't have a hot water tank, it is an on demand. I pulled the cartridge out of the shower, and that was the culprit. I just turned off the water to the shower until I can get around to buying the new one (we don't the the shower very often, so its not a big deal)

 

[zrock]

I would still check on demand has a max psi as well... most city systems are set in the 50psi range

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[Dobish]

inlet pressure is good to 150psi, tested to 300psi

 

[Dobish]

i pulled the cartridge out, and replaced it. that was the problem! When it was put in,it was crooked, and it looks like one of the pieces was all messed up.

of course i lost the set screw for the handle, so I need to order one of those for $12 (or just drill and re-tap the handle for a normal size screw!)