Moentrol, School me on this old 12178 shower valve

[Old_Smokey]

Hi guys,

I'm part-way through my first bathroom renovation - ripped everything out to the studs and starting over. This forum has been a super resource for all kinds of questions. Just yesterday I got my Maax Bosca tub installed and set in a bed of mortar. Everything went great.

Since I've got the walls open I was considering replacing all the copper plumbing and the shower valve. But I'm second guessing it now. It appears to be a Moen-trol valve as it has the stops and pressure balancing system in it. It's never leaked on me and works fine. Looks like the cold water stop might need to be inspected closer, but that has replaceable seals I think.

The number "12178" is stamped into the top. Is that the model number? I can't find much about it online.

My questions are:

1 - does this valve use a 1200-series cartridge?

2 -There are no tabs to mount the valve to the studs. I guess just use some copper pipe clamps and copper nails then?

3 - I can't find any specs on how far from the finished wall I should set the valve. The old shower was a bath fitter style insert. My new finished wall will be about 1/2" deeper than before, so I have to remove the angled pipe elbows here and reposition the valve. Meaning I'm removing it anyway. But I don't want to spend $175 for the exact same part if these things have a rep for lasting a long time.

I'm thinking don't replace if parts are still available. Let me know if that's a bad decision

 

[Tuttles Revenge]

Here is the link to the Moentrol on Moen dot com

https://www.moen.com/products/MPact...cludes_pressure_balancing_volume_control/3520

I didn't see any spec for depth of valve.. and the link to spec sucks.. click on the SUPPORT tab and you find some better info. Odd for Moen to not have good info for this.

 

[Sponsor]

 

[Gsmith22]

the larger round valve with what looks like a horizontal slot for a flat blade screwdriver to the right of the mixing valve is the anti-scald/pressure balancing valve. check out this video: for what is behind that.

It is this weird cartridge assembly with two hole filled tubes and may o-rings that slide past one another that is supposed to be the heart of the anti-scald/pressure balancing mechanism. It will eventually lock up (dirt, rust, sediment) and all you will have is cold water. Ask me how I know The part is available (I got one at Ferguson) but not widely available and it was $100. I had two showers with this same problem but I wasn't prepared to rip out the shower and plumbing so I had to pony up. If I were you, and in this far, I would pull that valve in a heartbeat and get something modern that doesn't have this part that is bound to fail and will probably eventually be not available. Oh, and the brass parts corrode/don't hold up well and become nearly impossible to get this valve out with just a screwdriver

The two check valves to either side will also corrode and leak and I think they may have been available but I don't remember their cost - they were cheaper than the tube thing.

For me, it would be a no brainer and already ripped out given my history!

 

[Old_Smokey]

Check valves are $30 and the balancing mechanism is about $80 here. So yeah, not cheap. A complete new Moentrol valve is about $180.

To remove the valve from the piping and reposition it, I'll have to remove both stops, the pressure valve and the cartridge for soldering, right? Or else I could torch the seals. That means likely replacing at least the cartridge and one stop, possibly the other stop and pressure unit. That's about the price of a new valve. Hmm answered my own question I see.

 

[Gsmith22]

the check valves have flats on them that you can put a wrench on so they should come out relatively easy. my pressure balancing valve had flats too but yours doesn't seem to have that (maybe I just can't see it the pictures?). the biggest problem is the brass of these things deforms when trying to take the valves out as they get corroded/stuck in place so even if you intend to keep the valve, you might need these parts anyway if they get damaged upon removal. One of my check valves looked fine from the exterior but was internally corroded and had a hole in the valve stem that broke as I took it out (the stem is hollow). Your pressure balance valve might end up in worse shape then mine only because it looks like you can only use a flat head screwdriver (or something similar) to get it out. that brass deforms easily.

I guess it can't hurt to try and take it apart as you have to do that anyway to remove the valve and reposition it, but I personally wouldn't keep an antiquated design that parts aren't readily available for. I assume these things will break on me on Sunday night with no way to rectify timely.

 

[Old_Smokey]

Thanks. Decided to replace it. I have plaster walls and no way do I want to cut into it again to replace this down the road. Picked up a new Moen valve and trim kit package for just a bit more than replacing the current internals.