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How to Install Moen Shower Valves

Tips for Posi-Temp Valves

As Seen On
by Jeff Patterson in Bathroom Plumbing, DIY Bathroom Remodel

In today’s video you’ll see how to install Moen shower valves, specifically the Posi-Temp valve.

What mistakes can be make this a nightmare?

There are many and that’s why we made the step-by-step video.

Let’s dive in!

What Does Moen Posi-Temp Mean?

What happens when the toilet is flushed while someone takes a shower (and I’ll be the first to admit this happens all the time in our home!)?

Toilets use cold water and reduce cold water flow from shower valves. Thus, it’s easier to get scalded from hot water when the toilet is flushed.

Moen Posi-Temp shower valves are pressure-balancing. The valve on the Posi-Temp shower faucet balances pressure to maintain a consistent water temperature if the pressure from hot or cold pipes increases or decreases.

Balancing water flow and temperature makes showering more comfortable.

That’s how the Moen Posi-Temp works in a nutshell!


How to Install Moen Shower Valves

Step one is to determine if the tub spout requires copper or threaded pipe. In this example the spout needed just a straight piece of copper.

Moen shower valves have specific tips for how long the copper should be that extends from the bottom of the Posi-Temp valve.

Solder copper pipes together for the tub spout and allow them to cool. Then connect them to the Posi-Temp valve using teflon tape.

Step two is to figure out how deep to set the Moen valve inside the stud wall. This is SUPER important. If shower valves are too deep or too shallow this will affect the look of the trim kit.

So it’s critical to know the thickness of

  1. Tile backer boards (typically 1/2″)
  2. Thin-set mortar (roughly 1/8″ for 1/4″ tile)
  3. Tile (usually 1/4″ or 3/8″ or 1/2″)

Most tile backer boards like cement board, KERDI-BOARD, Hydro Ban Board, and Wedi are 1/2″ thick. Using liquid waterproofing membranes like RedGard also add another layer of thickness, so don’t forget that.

One these variables are know then wood blocking can be set inside the stud wall.

Finally, Moen shower valves allow the use of PEX and copper pipes. That makes installation much MUCH easier because crimping PEX connections is simpler inside shower walls versus soldering copper.

Watch our video for all the details


Moen Shower Valve Installation (Option 2)

This next tutorial shares a second option for doing a Moen shower valve installation.

Instead of the tub shower being in a basement, it’s on a second floor.

Also, we used copper for both the tub spout and riser going to the drop elbow.

Some installers prefer copper for both these sections of the shower valve.

In addition, this particular Moen valve had PEX barbs for the hot and cold water supply lines.

The Apollo Pro Crimp Rings make PEX installation much easier. They are definitely worth checking out.

It’s always nice to see different Moen shower valve installation methods.


What’s Next

Moen shower valves are just one part of our latest bathroom remodel.

If you’re doing a bathroom remodel and want to simplify the process enroll into Bathroom Repair Tutor’s Video Library

We show how to build showers (Schluter, Wedi, Curbless, etc.), install tile, upgrade basement bathrooms, and more.

The extra guidance is invaluable

Enroll Today



Jeff Patterson

  1. Len says:

    Thanks for the insightful tips.

  2. Thanks Len, hope they help

  3. w jordan says:

    Why don’t you have your stuff fixed where we can save to out Pintrest accounts. I have one set up just for house things. Would love to have you stuff there.Thanks

    1. Thanks for asking, you can install the Pinterest button in your browser and hover over the pictures and save that way. It’s super easy to install, I even did it, lol

  4. Tim Brogdon says:

    I had the perfect rough out depth for a positemp (3/8″ proud of wedi board) until my wife decided she wanted 12×24 tile and I used a 1/2″ square trowel. So instead of a final 3/8″ of tile from wedi board, I now have 1/2″+ and the moen rough out cover plate is 1/8″+ behind face of finish wall. Is this going to be a problem? How much tolerance does the valve have?



  5. Peter J Stock says:

    that was an awesome video, the best video presentation I’ve seen for a while. (brisk audio, and the fast motion video saves a ton of viewing time.)
    A) what is the black plastic ring for? you didn’t seem to use it.
    B) it looks easy (well easy-ish) when you are working from an as yet untiled.tub area. How about a video for retrofitting a valve like this into an already tiled/finished bathroom?

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