How to Install a Moen Posi-Temp Shower Valve…PEX and Copper Pipes — by Home Repair Tutor

How to Install a Moen Posi-Temp Shower Valve…PEX and Copper Pipes — by Home Repair Tutor


In today’s video, we’re going to share
several tips on how to install a Moen mixing valve in a tub/shower combo. So in this project,
we had to put in a basement bathroom. So in our prior videos, we shared how to level the
floor, how to put in the bathtub, and now we’re moving on to the Moen mixing valve.
This is the step right before installing the backer board. By the way, the backer board
that we used for this shower was HYDRO BAN Board. But in today’s video, we’re going
to share several tips, and at the end we’ve got a surprise for you that’ll help you
out with your project. Okay, so we’re going to install this Moen
Posi-Temp rough-in valve. And we’re obviously putting this on a tub. So one of the stipulations
Moen wants is that you can use PEX for everything else except for the tub spout. They want you
to use a threaded pipe, like a hard pipe, like a brass fitting or something or copper
for the spout. Now, to determine which one you can use on
that, it really relies on your finish trim. So this is our tub spout. And as you can see,
this is made to just slip over ½ inch copper. So to determine, you know, whether you have
to solder and use copper really relies on this tub spout. If you had a different type
that actually just threaded into the spout, then you could just use all hard pipe coming
out of the bottom of this. But since we have one for copper, we’re going to do a copper
adapter to it. Basically for the tub spout, you can go between
6 and 11 inches, 11 inches being the maximum amount to the tub spout. So I want to go with
the maximum on that. I kind of like having my tub spout a bit further away from my valve.
So we’re just using emery cloth to clean the inside of the fittings; super important
to do that. You can also use the emery cloth to clean the outside of the pipe.
Just make sure you sand all your ends. Now you want to apply flux to the inside of
the fitting and the outside of the pipe. So in this case, we’re just going to be
applying our solder. Notice how Steve created a little hook on the end of it. That way,
when you heat up the pipe using Map gas, which we totally recommend, that little hook can
reach around the angle portion of the pipe. And as it melts, it can go into all of the
areas that you fluxed. So in this case, we’re heating up our elbow.
Again, this only takes a few seconds. You want to hold the flame onto the elbow and
constantly dab with your solder until it goes into those joints. And in this case you can
do both joints. Now I will say here Steve is holding it with
his bare hand. You got to be careful doing that because the pipe may heat up, and it
could burn your hand. So just be careful when you’re doing that.
At that point, put some Teflon tape on it clockwise 6 or 7 revolutions. And you can
thread this in to the port. So this has a little arrow saying “up.” So it’s the
one opposite of that. We’re just going to hand-tighten this section
first. You don’t want to cross-thread it, that’s for sure. Because if you cross-thread
it, big problem with leaks later on. Just sit this flat on the wall and see if
you got it in the right position here. So we’ll get our two ports that connect to
our PEX. Just going to use these little elbow adapters.
Use about 6 to 7 revolutions of Teflon tape around these fittings because that’ll help
keep them nice and water-tight against the mixing valve. And we have these two fittings
that will supply us with the hot and the cold water to the valve. We’re going to be using
PEX in a moment here, but we’ll show you how to put that all together. So again, it’s
very, very important to hand-tighten those fittings first so you don’t cross-thread
them, and to use channel locks next to get them nice and tight.
Again in this case, we need them to face upward because we’re in a basement. The supply
lines are actually coming down on into the bathtub area.
Okay, then for the shower port you can use PEX. So we’re going to go ahead and put
an adapter for the shower head. Another 6 to 7 revolutions on this fitting.
And then use channel locks to tighten it down. Determine where you want to put your tub spout.
I typically recommend about 3 inches off the tub deck. That seems to be a normal location
for it. So we’ll put some blocking for behind this valve here, about 15 inches. And then
we’ll also get some blocking to secure this pipe for the tub spout as well.
So in this scenario we’re able to easily put blocking behind the wall. So we’re just
going to screw some blocking in behind this wall. Basically I’m just grabbing that from
the back of this 2×4. We’re just going to get some ¾ blocking to attach to that.
So each scenario is a little bit different. You want to get behind your wall.
Add some ½ inch paneling as well. So basically an inch and a quarter off the back of the
stud on this particular situation. So now that you see when I put that in place, we’ll
be about 1/8 inch outside of the area there. So right about there.
So for PEX, you just need a crimp ring. You put the crimp ring onto the pipe first. You
slide the pipe over your fitting. And then you use a crimper to crimp down on that. And
there actually is a go-no-go gauge that you can check all your fittings, but we didn’t
show you how to use that here. Again, we actually had to do a splice with our cold line. You
see here, we have a cold line coming down from the wall. So we had to make a splice
there, but that’s not a big deal with PEX. You can see why we use it in this situation.
There we’re just lining up how far down it needs to go over the mixing valve fittings.
So the blue is our cold water supply line. We’re just crimping it here. And then the
red is our hot water supply. So anchor this into our location here.
This is really important. You want to double-check that the valve is centered on the tub drain.
And then use galvanized screws to secure it to your wood blocking. So again, definitely
double-check that the valve is centered before you screw it to any wood. And the same thing
with your tub spout. We’re slightly off, so now we can adjust
this towards 15 1/8. As you can see here, the tub spout, the mixing
valve, they’re all centered on that waste overflow and the drain and the tub.
I would advise putting some blocking down here to attach. Just get something on this,
the tub spout. Here, we’re using 3 inch galvanized deck
screws to secure the wood blocking inside the stud wall. Remember, don’t ever use
drywall screws for this because drywall screws are not as strong as deck screws, and they
will rust out in a tub area. And then you just put a copper strap. And
this will make it sure that the spout is secure. So as you could see, we don’t have a lot
of head room in this bathroom at all. So I’m actually going to go with my standard height
of 78 inches for this. Anything more than that, I’m not going to be able to thread
on my elbow. And again, you just want to have this port recess behind your backer board.
So if you go even with your stud, then that’s far enough. So basically the spout from the
back to this is about an inch; just call it an inch. So just as long as your blocking
is an inch behind the front of our stud, that’s good.
So we’re just predrilling our 3 inch deck screw into this blocking before we move it
up where it needs to be. Again we’re just ensuring that it’s at the right depth and
then totally screwing it into the stud. Add a deck screw at all four corners of your
wood blocking: so top right, top left, bottom right, bottom left. Secure that. Make sure
that it’s at the right height. Mark the location for the drop elbow. Cut your PEX
to size. Add a crimp ring over top of the PEX. Slide your drop elbow over that, and
secure it using the crimper. Super easy. We love PEX. It’s awesome. And do the exact
same thing for the fitting that’s down in the mixing valve.
Okay, you can get one of these plugs from the home store. It kind of helps out to test
everything, but also helps kind of really figure out where the center is.
The drop elbow can also be secured to the wood blocking using galvanized screws.
Okay, then to test your whole system, I would just put a SharkBite cap on the end of this.
This will be nice and easy because you can remove it easily, or you could just cut the
pipe off. There you go. Give us a thumbs up if you like the tips in
today’s video. Now here’s the surprise that we mentioned
at the beginning, and that is we’re going to be making an online course that’ll show
you step-by-step how to build a shower, specifically a tub/shower combo. If you’re interested
in that course and you want to check it out and also get our free guide on how to build
a basement bathroom, you can click right here, enter your name and email address, and we’ll
send you the guide, and you’ll also get access to the different modules within the
online course. It’s awesome, it really goes into great detail, and we know that it’ll
help you out with your project. Thanks for watching today’s video, and we’ll
see you in the next one.

16 Comments

  1. Great video-I’m in the process of a complete bathroom renovation and have been using many of your guides (VERY useful-thank you!).

    Would love to see a video of finishing this bath over that valve (I’m using the same one).

    Also, do you have any tips to help get the valve to the correct depth (ie not too deep, not too shallow)?

  2. You can avoid sweating copper pipes by shopping for 12" and 6" threaded brass pipes. This deal on Amazon made my setup affordable and eliminated any risk of bending due due to the tub spout being whacked. And unlike copper it will last well beyond 30 years. https://www.amazon.com/Chrome-Plated-Brass-Fitting-Nipple-Schedule-x/dp/B00K0D30MC/ref=sr_1_3?ie=UTF8&qid=1540857271&sr=8-3&keywords=brass+pipe+12%22

  3. How "deep" into the wall to set the valve is very difficult to figure out from vague instructions that come with mixing valves 5:25 in video. The black plastic mud ring and the "thin / thick" wall options all make it pretty confusing to the DIY world. It looks like you aimed to get face of the black ring to be flush with future tile surface and achieved that by building up behind with blocking. I generally put 2×6 blocking at back of wall so there is a 2" space for the valve and it works out well (3.5" stud minus 1.5" thick 2×4). Seems you achieved almost same thing by using 1/2 plus 3/4 OSB built onto the 2×4. This is an excellent video series btw — I've renovated many bathrooms but in every video I see ways to fine tune the work I do 🙂

  4. Very sloppy job applying Teflon tape. Any tape left inside the threaded area will eventually break off and clog the valve. All tape should be on the threads only and not inside that tubing.

  5. Awesome info. It is difficult finding vids on unique circumstances. I have a very similar setup and my biggest issue was determining the depth of setting fixtures with a tub surround. The installation instructions never seem to be set for my conditions. Thanks!

  6. I love PEX, but gotta ask what brand crimpers those are. I use rings also (DIY'er) and my crimper is so much harder to close than those seem. It looks like little effort where mine requires some serious pec skills.

  7. Why would you use Galvanized screws to hold the valve in place? If it gets wet the crappy wood you used will be the first thing to go leaving the screw with nothing to hold it in. I'm no plumber to be judging your work but I would have blocked that a little  better for a valve that will be getting used daily.  I admit have a tendency to over kill in areas I don't want to come back to.

  8. Great video are Moen all the same I have mid -90's and don't want change the Mix Valve we going to order 2 Moen T2153EPORB Brantford PosiTemp Tub and Shower Trim Kit your thoughts thanks in advance. Steven

  9. Nice clear audio on red=hot, blue=cold. obviously.

    Mumbling at crucial step on how to set depth of mud ring vs finished tile surface.

  10. Something to keep in mind, if the branch going out the top of the mix valve to the shower head isn't long enough, you'll have water leak out the shower head even if the stopper to the tub spout is open. It has to do with how much pressure you have in your lines. Sometimes there's a bit more water in the lines that can come out of the tub spout so it'll want to go up that too pipe. If it's long enough, the water stack gets heavy enough to push back down and prevent it from spilling out the top. Just go higher, rather than lower on your shower head. Source: am not a plumber, I'm a carpenter. But I have seen this happen on 2 jobs before and asked a plumber how to stop it.

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