Latest Discussions : Plumbing


08:06AM | 08/28/03
Member Since: 02/12/03
19 lifetime posts
Having vexed the fine people at Moen, I turn now to the collective wisdom of the B.V. Bulletin Board for thoughts on this problem.

A quick picture of the issue: New construction, 2nd floor, full bath. Brand new Moen Posi-Temp shower assembly. All copper pipes.

After installation (done by our plumbing subcontractor) turning on the water caused a steady stream of water to come out of the spout and a very steady flow from the shower head.

Plumber diagnosed that we had a water pressure problem. This was confirmed with use of a water pressure guage (90 psi). This problem was resolved with a pressure regulator. Now the house water pressure is about 50 psi.

Unfortunately, the shower problem persists. I spoke with the fine folks at Moen (we otherwise love their products) and confirmed that the distances from the valve to the spout and shower head were within the ranges for this product.

The Moen folks thought perhaps the cartridge for inside the valve was faulty. A replacement was sent and installed - still...same problem.

Exasperated, the Moen folks suggested perhaps the pipe from the valve to the spout had a blockage of some sort. We removed the pipe...looked insde with a flashlight, no blockages.

Any thoughts? Anything obvious we've missed.

In order to mitigate the problem, Moen sold us a very nice flow control valve for the shower head - this stop the water from coming out of the shower head, but there's still a trickle and frankly the flow coming out of the spout is not very strong (IMHO).


05:35AM | 08/29/03
Member Since: 06/30/03
2 lifetime posts
Unfortunately, I can only offer my experiences with the same thing. I bought a new tub spigot (not Moen) and installed it and had the same thing happen. So off to the hardware store to change for another one... Rats! Same thing! I asked everyone I could and got the same answer you got. Water pressure! But if that is so, why didn't my old spigot leak? My temporary solution was installing a shower head valve also. It seems to me that this ought to be an easy fix however nobody seems to know what that would be... I'll keep watching here for help gems...

erik peterson

04:28AM | 11/24/03
Member Since: 06/23/03
223 lifetime posts
Install what is called a "double-ell" between the valve and the shower riser (inside wall) this will take care of the must go to a professional plumbing supply store and make sure the clerk has the experiance to know what this device is (obscure these days, used to more common) erik


06:04PM | 06/20/15
I use pex pipe and shark bite fittings for many showers with success. The last one i plumbed i experienced the above problem. The shark elbow for the tub spout had a reduced opening inside and once i changed it and the pex for the spout only, no more problem. Diverted too much water up due to the restricted opening. I dont think the pex was the problem because it acted the same way after only changing that piece of pex for copper.


07:29AM | 07/24/15
change the valve up
side down


08:23PM | 07/25/15
The moderator will not allow me to give the correct answer as they keep blocking me from signing on.

Contact me Tieger plumbing my E mail is readily available and I will tell you how to alleviate the problem

Seems then new moderator does not like to be corrected


12:23PM | 01/14/18
Our Stacking issue fixed with above suggestion to remove the shark bite elbow and replace with copper fitting, leaving all other pex in place! Thanks!


06:44PM | 03/06/18
According to Delta Faucet, it is called shower rise. It is caused by the spigot discharge pipe being to short of distance from the valve body. According to Delta it has to have a minimum drop of 8" from the valve and no more than 18". Just installed a new Delta faucet and have the same issue and they said it was because of incorrect installation.
My drop is constructed of 1/2 copper pipe and is 7.5 from the valve to the elbow. I could not find anything in the faucet installation instructions that came with the faucet, but was told this by their HELP team. Unfortunately my new shower is ceramic and I will have to live with this issue. Or perhaps try to find a cut off valve to install at the shower head.


05:04PM | 03/10/18
Changed shower heads


05:04PM | 04/07/18
Sounds to me like the Shower valve is installed upside down. Been a Plumber for 24 years.


11:47AM | 04/29/18
Hi all - found this forum when trying to install a Moen INS2153C tub/shower valve, and experiencing "stacking", or flows from the shower head while the tub fill is running at maximum. My distance from the valve to the shower arm was the prescribed 46", the valve was installed proper side up/down, and the lines had been flushed prior to hookup.

While the inside diameter of Pex is the same as the opening in the tub spout (and therefore it seems like Pex should be OK), the actual flow capacity of the FITTINGS that Pex uses, is less than the flow capacity of the Pex pipe itself.

IMHO, the Engineering of valve assemblies like this one (any that rely on blocking the flow at the tub spout to activate diversion of the water to the shower arm), should be re-thought, given the popularity and ease of use of Pex.

My solution was to purchase one of the newer design shower panels, which require only a single standard Hot stub and a single standard Cold stub. I brought those out of the 4.5" circle I had cut for the Moen valve. These new models have the same type of connection as a sink tap, dead simple. Upside: 1) Nicer functionality (because the show panel has more choices of water flow; 2) No need to break into the wall and undo existing work; and 3) I finally understand why they say to use copper to the tub spout. IMHO this is a restriction that could be eliminated if the mixing valve manufacturers would re-think the existing design in light of popularity and ease of use of Pex. It's not like the panels are materially more expensive that the mixing value, certainly as a % of the bath reno project overall it's a rounding error.


06:47PM | 10/02/18
I am a master pllumber in Houston, Tx and have seen this problem present itself a couple of times. The 1st time the issues was that the installer used what we call a drop ear 90 to stub out the tub spout. This caused too much resistance causing water to back flush to the head. The 2nd time was that the spout distance was stub out too far from the valve causing the water to travel upward out the shower.


04:30PM | 04/08/19
I have this problem with a new Moen posi-temp, also (from model kit 82603). Valve to tub spout tube is: Shark-bite > Copper > Shark-bite 90 > Iron Pipe (PEX everywhere else). Valve drop to spout tube is within the 6-11 inch tolerance.

There is no stacking issue with the threaded spout uninstalled...

Moen support guy said valve must be 32 inches from tub floor (mine is 29). ??? >:(

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