My shower head leaks water while water is coming out of the tub spout. It only leaks when the hot and cold water are mixing. It is a Moen valve. I have already replaced the cartridge and diverter- no change. Copper was not used for the riser, plastic tubing (peks?) was used- could this make a difference?

There should be a restricter in the valve that keeps the water rising up in to the shower riser. So if anything has been done laely except changing the cartridge, that could affect the flow.

Also it the tub spout is corroded in any way that may make the water rise into the shower riser and out the shower head, so maybe changing the tub spout might change the problem.

LetmetellU,
You never fail to amaze me. I once advised you to check with a working plumber before you posted. Remember? That was back when you informed us that a attic revent coluldn't be snaked. Now you did it again!

There should be a restricter in the valve that keeps the water rising up in to the shower riser.
Had you ever installed a Moen tub/shower valve yourself you would have know what prevents water from leaking out the shower head when filling the tub. Sorry Charly! But there is no restricter in a Moen tub/shower valve
While I guess a faulty diverter spout might divert somthat affects the shower.e water up the shower raiser but that's already been replaced, ( go back and read the complaint) . What does stop the water from climbing up the shower raiser when you fill the tub? Pay attention,LetmetellU!! There will be a test and questions later. Why it's simple head pressure that keeps the water pouring out of the shower head when filling the tub. From
Let me explain. Water, like electricity, will always seek the path of least resistance. Think about it! When you open the valve to fill your tub water under pressure goes down 8 inches and out the open spout. When you close the spout diverter the water has to clime up 28 inches to exit the shower head. That 28 inches presents a back pressure of a little over 1 PSI. Not very much but enough back pressure to keep the water flowing out of the spout which has no backpressure at all.
And that completes your lesson LetmetellU. You may own a plumbing shop but t5hat sure don't make you a plumber. One more time! Check with your plumbers before you embarrass yourself by posting here!!
Which brings us to your problem Mat22 and the solution to repair it.
About the only thing left is the house pressure itself. If your house pressure's over the top it will overpower the raiser back pressure and send water up the raiser out the shower head.
Do you have a PRV( pressure reducing valve) installed where the water enters the house? Do this, purchase a hose bib pressure gage ,(see image) and check your house pressure. It should fall within 40 and 60 PSI with the average 45PSI.
Bring your house pressure down and I'll bet your leak goes bye-bye. Good luck, Tom

Matt22,
Please answer my questions and let me know what your house pressure is. Regards, Tom

speedball1

I have not had achance to check my house pressure yet. I will let you know when I get it. Thank you for your help. mat22

speedball1

I finally checked my pressure-69 psi. I put on a prv set at 50 psi and it solved the leaking shower head problem. Thanks for your help.

Thanks for the update. I'd like to take credit for solving your problem but outside of a faulty diverter spout too much pressure was the only answer. Easy solution/ easy fix! Thanks again Tom

speedball1

Iwould like to post a comment for your help but it says to click on the "scales above". I don't see any scales to click on. I know this is'nt a plumbing question but maybe you can help me here too. Thanks again.

I come on board a long time ago and still use the old skin. I guess there are more then a few to choose from. I appreciate the gesture but your thanks are good enough for me. Thanks, tom

Matt your main problem was the use of the plastic tubing peks, it won't work with the tub spout deverter when the h/c water is mixing, you will always have a small amount of water leaking back into the tub while showering. Hope this is helpful, it worked for me. Paulwin25

I don't think I agree with paulwin25. I think Tom gave an excellent, and right on, advice to Matt's problem...

Thanks Milio!

Paulwin,
In addition to piggybacking on a closed thread that was over a month old if you had read the the posts you would have realized the problem had already been taken care of. And what in the world did you mean by this?
Matt your main problem was the use of the plastic tubing peks,.
Another error on your part was in not reading the complaint. You answered,
you will always have a small amount of water leaking back into the tub while showering. His complaint was exactly the opposite. His complaint was that water came out of the shower head while he was filling the tub.
Your third error was in double posting and your forth was in posting here at all.
Have yoursaelf a great week end, Tom

Paulwin25
I think you are right. I put a PRG on and it helped but did not correct the problem. The Moen rep said that it was the peks coming off the tub spout creating "stacking". I don't want to tear out tile to replace the peks, so I might have to live with dripping. Thanks for your help.

I have to put me 2 cents in after reading all the posts. I installed a new Moen shower/tub spout. My shower head also leaked while the tub was filling,, it turned out the when I screwed the spout on I had to use a PVC bushing between the copper pipe and the spout to add length. This length was so the spout would set flush when screwed in, trouble is the ID diameter on the PVC was somewhat smaller than the copper and caused restriction/back pressure and hence a leaking shower.

Oscar,

Welcome to the plumbing web site, Please read the post you are responding to a closed thread that is over 11 months old and the problem had already been taken care of, Thanks.
John