Moen cartridge


Last month I had to have a plumber come out to my rental to fix a dripping faucet and shower head, and to check on a leak into the unit below mine. He came and replaced the moen cartridge, but put it in wrong, reversing the hot and cold. He came back out to fix it and to check on the leak which had become worse than before. (the downstairs resident wasnt home the first time for him to check on it) After he reinstalled the moen cartridge, the leak stopped. So here is the question (enough with the run on sentences!!)… would the moen cartridge that was installed wrong have anything to do with the leak that miraculously stopped?

Thanks for the input,


If there was a pinched O-ring it could result in a leak, depending on what O-ring was pinched, missing… Raymond Wand Alton, ON

well seeings how he fixed the shower head too, i’m going to assume that the tub faucet was the other issue and not the sink faucet. anyway, if the stem was installed wrong, he should have caught it because the escusions probably would not have fit right and that will cause a leak. some models are different, but my experiences have been that they only fit “right” one way. hot and cold may have seemed switched but more likely the hot, cold, and off were all out of order due the the ports on the cartridge lining up differently when the handle twisted it, so he likely realligned the handle and called it good. hope that helps

How much you wanna bet he had the Hot & Cold lines reversed and didn’t want to tell you that he screwed up.

I have installed the cartridge backwards and got hot and cold reversed. Same in homes inspected. To ensure its not the cold/hot line reverse I feel the pipes and sure enough they are correct. That leaves the cartridge. Poor design if you ask me. The cartridges are not marked very well… and I am not fool proof. :wink:

Raymond Wand
Alton, ON

A good number of valve mfg. make shower valves reversible so that commercial back to back installations are kept straight in the plumbing walls.

Regards Bill

Thanks for the input on installation, but would the reversal have anything to do with the leak?



Pinched O-ring?

Raymond Wand
Alton, ON

also read my first post. it’s also first hand experience.

It could be a O-ring which is damaged, you may not even see the damage. If you miss an 0-ring you will get a leak. Some O-rings are very small and fine, and can be damaged and you would not know it.

Raymond Wand
Alton, ON

Reversal should not have anything to do with leak the other respondents have probably identified the situation though.

Regards Bill

A Moen cartridge can’t be installed wrong because either way it’s the same.
You only have to remove the handle and rotate the “center stem” part of the cartridge (or the handle) 180° to change cold/hot to left (or right.)

This was a big Moen sales promotion feature years ago, faucets can be installed back to back with hot/cold supplies conneced to either side then just install the handles 180° oposite.

not to mention the crazy oblong oval offset oring made for some of them. if it’s not on just right…headache.

To answer your question about the possibility of the hosed up shower causing the leak in your downstairs neighbors apartment the answer is Yes that could have been the source of the leak all along. If the plumbing was leaking inside the wall cavity where the shower controls are then there is a good chance the water was finding its way downstairs. Once the new cartridge was correctly installed and the leak upstairs stopped there was no longer a source of water getting downstairs. The water had to be coming from someplace.

As a licensed plumber for the past 30 years i can tell you from experance that all 1200 series moen cartridges will rotate to change hot & cold from left to right. Delta cartridges will also rotate to change.
As far as a leak You would have to take the esc. cover off and look for a wet wall.

I have one in my house right now that is installed backwards, and has been since I bought the place. It has never leaked.

I’ll fix it when it needs to be replaced.:wink:

All you need to do is remove one screw, pull the knob off, rotate it half way around and put it back on.

yeah but your more apt. to break it after you fix it, or get scolded because your used to it the other way.

I know how to fix it, but I don’t want to.

neener neener neener.