View Full Version : shower and tub water at the same time

05-23-2010, 08:42 PM
In a new bathroom installation in the basement, I installed a new shower and tub faucet ( Moen brand ).
I followed all installation instructions including the sizing of the pipes , height and placement of various parts.
The problem is that when the water is supposed to come out from the tub spout only, there is some amount of water coming from the shower head also. This happens in 2 or 3 points as you rotate the handle from off to cold and to hot.

I tought I got a defective item. I then replaced everything with a Delta brand shower and tub faucet.
However I got the exact same problem. The water comes from the shower head at exact those 2 or 3 points in the rotation arc.

What is the reason?
Can someone please explain how is this supposed to work ( setting to spout only vs setting to shower only - what makes it work one way or the other )?


05-24-2010, 06:36 AM
Tell us what type of pipe material is used to connect from the valve to the tub spout. IF it is PEX or CPVC, go back to read the installation instructions for the valves and you will have your answer.

If you installed the valve correctly, then too-high water pressure in the building can also cause that symptom. Can you get a gauge and check the pressure at a hose bibb?

05-24-2010, 10:11 AM
If you were able to replace the valve, then it should be visible so you can show us a picture of what you did. "Too high pressure" is almost NEVER the cause of your symptoms, nor have I ever seen it happen.

05-24-2010, 11:56 AM
As you turn the valve through the temperature range, there will be points when you have both the hot and cold at near full volume. I'm guessing it is then that you get the spill-over to the shower. If the valve is not installed upside down, or you don't have one that says you can only use one or the other of the outlets, then the piping that you used has too much flow restriction to the spout, and it is backing up and spilling over to the shower. Some valves require you to cap one of the outlets, and use a twin el to branch off to the shower, if needed. Some valves have one outlet that is larger than the other (it should go to the tub), and if you get them mixed up, you'll get that problem. Pex and CPVC wall thickness is too large, and it restricts things too much, and is the most likely reason it is spilling over into the shower. Water takes the least restrictive path. If the pipe going to the tub is restricted, there's enough flow so it will also go out to the shower...just like if you pulled up the divertor.

05-24-2010, 08:55 PM
Thanks for all the answers.
Yes, I used Pex ( plastic ) pipe for all connections ( 1/2 inch pex ).
Yes I think the reason for my problem is that the pipe from the valve to the tub spout should be copper instead of pex - I can see it now specified in the instructions.

At this point, what do you think if I replace the pipe to the tub spout from 1/2 inch pex with 3/4 inch pex.
That should allow a proper flow to the tub spout and chances are 100% that it will solve my problem, right?

Using 3/4 inch pex would be best cost for me since I do not have the tools to install copper.

05-24-2010, 09:31 PM
In addition to having a smaller internal diameter, pex adapters have further restrictions, so no, it probably won't make a difference because the adapter to get it into the valve and the spout will restrict it back to the same diameter. Bite the bullet, either pay a plumber to solder it in, or buy the tools and some pipe and fittings and practice a little. A third option is to find a friend that can solder it for you. Also, how did you get the spout to be stable if you used pex? It is floppy - the spout needs to be stable.

05-24-2010, 10:47 PM
Here is a picture.

You can see that the spout is stable because all the fittings are metal and the one at the end is screwed in the 2x4 wood.

The valve ( the big piece in the picture ) comes with the 4 openings threaded ( you need to screw in an adaptor anyway ).
I was thinking that instead of the 1/2" adapter to buy a 3/4" adapter. And then the piece that is screwed into the 2x4 and it connects to the spout, to buy one with a 3/4" entry instead with a 1/2".

Do you still think that it won't solve the problem?

05-25-2010, 05:42 AM
If you cannot solder, then get two 1/2" brass nipples of the appropriate length and join them with a brass coupling. Then screw a brass elbow on the end and use that for the drop pipe.

05-25-2010, 10:47 AM
And yes it will solve your problem...
To use the tubing specified in the directions you disregarded...

05-25-2010, 12:27 PM
You guys can be hard....

05-25-2010, 12:28 PM
But cool at the same time. ;-)

05-25-2010, 01:14 PM
Oh yes you are all tough ha ha.

So anyway you didn't answer my question.

Given my options, I'll try to find "two 1/2" brass nipples of the appropriate length and join them with a brass coupling"
but if I cannot find these, my next option is to use 3/4" pex tubing and fittings for 3/4" .

The 3/4" tubing and fittings are plenty enough larger than the 1/2" copper pipe and fittings.
So I think it will work. What do you think?

05-26-2010, 08:29 AM
I think if you cannot find brass nipples, a coupling, and an elbow you are not looking very hard, and you WILL need a brass nipple when you attach the spout.