Moen Posi Temp Shower Cartridge Valve Plugged

[Etbrown4]

Like most municipal water systems, and private wells, we have plenty of sediment which eventually plugs a shower valve. Some of the passages appear to be 1/4" or less, so we find that with typical sediment you can have very limited flow in 10 years or so.

Interested what the old pros like Terry suggest, other than valve replacement.

 

[Jeff H Young]

Won't it blast out removing cartridge ? Perhaps replacing the cartridge but the valve body itself is closing up?

 

[Sponsor]

 

[Etbrown4]

wont it blast out removing cartridge ? perhaps replacing the cartridge but the valve body itself is closing up?

The cartridge area is clear. There are some obvious small passage ways on the right side if I remember correctly and they can easily close up.
Guessing the usual cure is new valve.

About 20 years ago, I decided one was mostly full of sediment so thought I'd experiment. Drilled a 3/16" or so hole in an obvious passage and cleared it well with coat hanger and air. Tapped the hole and inserted the correct size stainless hex Allen. screw. I have the sizes written somewhere. Started working well.

It's not difficult once you figure it out. Was curious what others have done.

 

[Nebojsa]

Is there a way to install a filtration system.

 

[Etbrown4]

Is there a way to install a filtration system.

There are plenty of inline water filters available.
Still curious what Terry has done in these situations.

 

[Terry]

hj has mentioned the fact that most shower valves have four ports. The water first goes down, in case there is a tub spout, and if it's shower only, that gets capped and the leg on the bottom can fill with sediment.

 

[Etbrown4]

hj has mentioned the fact that most shower valves have four ports. The water first goes down, in case there is a tub spout, and if it's shower only, that gets capped and the leg on the bottom can fill with sediment.

The valve looks like this. Pretty sure the bottom leg would supply the tub if you have one.
When these plug with sediment and the flow is poor, is there any alternative but to replace them? (other than the drilled hole I mentioned)

 

[Toshbu]

The valve looks like this. Pretty sure the bottom leg would supply the tub if you have one.
When these plug with sediment and the flow is poor, is there any alternative but to replace them? (other than the drilled hole I mentioned)

Hello ETBrown4 and Terry too!
Did you get a resolution to this issue? I'm having a similar issue with no significant flow out of the shower arm/neck. We verified the shower head wasn't plugged. Flushed valve body with cartridge removed, even blew air through Shower arm/neck which comes out strong out of the hole in the bottom of the cartridge chamber. Yet after all that, still no significant flow upward. I'm stumped!

Would appreciate any advice or help from anyone. I joined the forum today after being a long time reader as I have not been able to overcome this flow issue out of the shower on Moen Posi-Temp valve even after 3 cartridge changes.

Thanks in advance!

 

[Jeff H Young]

so with shower head removed little water comes out. did water blast out through hot and cold port? its pressure balanced so if the hot or cold is restricted both will be reduced. piping plugged on way or at your valve might be the problem

 

[Toshbu]

so with shower head removed little water comes out. did water blast out through hot and cold port? its pressure balanced so if the hot or cold is restricted both will be reduced. piping plugged on way or at your valve might be the problem

Hey Jeff,
Yes, with the shower head removed, little water comes out of the arm. When we turned on the main, with the cartridge removed, we get full flow shooting across the shower to the back wall from the valve.

I've connected air line with 110 PSI through the shower arm, and I get a very strong flow of air out of the bottom hole in the valve body. So much so, I cannot hold my finger over the hole to stop the air. So why water doesn't flow up to arm is a puzzle. I agree something seems to be blocking the flow of water, upward to the shower circuit.

I've noted the cap on the bottom/tub outlet of the valve is very close to the valve. I do not see any 1/2" copper pipe hanging out of the port, with a cap on it as I expected. Seems like it's an internal cap in the port opening. Maybe only a 3 port valve but speaking with Moen, the only 3 port (shower only valves, have isolation stops on the valve. This one doesn't. Looks like a 2520.

I've thought about trying to adapt a garden hose to the end of the shower arm and try back-flushing that direction since the air didn't blow anything out.

I also liked the suggestion I read in a thread about using Sulfamic Acid to try to dissolve any debris that may stuck in the internal circuit that runs from the bottom (tub outlet) of the valve to the top (shower outlet).

I am open to any other ideas as changing the valve out will be extremely challenging due to access.

 

[Jeff H Young]

not 100 percent but I think your barking up the wrong tree with the tub port plugged theory.
if for example the hot water pipe on way to valve or at valve was plugged (or the cold) water would blast out the valve body with cartridge removed. spraying out mostly from the good side . before proceeding a call to Moen tech might confirm whether a clogged tub port would effect shower operation

 

[Toshbu]

not 100 percent but I think your barking up the wrong tree with the tub port plugged theory.
if for example the hot water pipe on way to valve or at valve was plugged (or the cold) water would blast out the valve body with cartridge removed. spraying out mostly From the good side . before proceeding a call to Moen tech might confirm whether a clogged tub port would effect shower operation

I see that Moen has a test plug #101975, but I can't find it in stock anywhere. I was thinking that might be another way to flush the tub/shower circuit within the valve. Any thoughts? I was thinking of building one with an existing cartridge by taking out the guts, cutting short and filling with silicone. Good thing this is an extra shower for us and not a priority to resolve otherwise I think I'd be cutting out and replacing the valve.

 

[Jeff H Young]

Toshbu, You can blow air down shower arm and it blasts through to the valve . Perfect! no problem there. With cartridge removed, water turned on water BLOWS THROUGH BOTH HOT AND COLD PORTS valve has no problem your in perfect shape!
other possible problem is water is NOT coming through Both and one side of valve or piping is plugged somewhere possibly right at the connection to the valve . or of course a problem with cartridge

 

[Tuttles Revenge]

What we know:
Water flows freely from the cold out of the open valve. Cold OK.
Air flows freely from the shower to the open valve. Shower passage OK.

What we don't Know:
Does water flow from the Hot side through the open valve. Introduce air to the hot side of your water system, likely at the water heater or washing machine connection (garden hose threads=easy) to verify,.

 

[Jeff H Young]

was not specific if hot and cold water was flowing through the ports . I suspect not as if it did there would be no problem

 

[Toshbu]

was not specific if hot and cold water was flowing through the ports . I suspect not as if it did there would be no problem

Hey thanks for the contribution to the discussion Gentlemen.
To answer Tuttles Revenge, yes, both hot and cold water, come out of the sides of the valve while the cartridge is removed. I also get both hot and cold out of the shower arm but at a very reduced pressure.

This photo shows my understanding of the waters path from the mixing chamber. Initially downward, then, because tub circuit is blocked the water will naturally follow the circuit upward and into the shower circuit. The area I've marked is where I suspect there may be a partial blockage.

Thoughts?

 

[Terry]

I had one instance where soldering on the vertical, solder had flowed downward and blocked most of the bypass channel. I wound up replacing the valve. I now solder those on the horizontal first whenever I can.

 

[Jeff H Young]

Tosbu, in post #10 you mention about not seeing pipe sticking out bottom , I can't remember specifically which brands but they used to come with a plug in box to be used for shower only operation so we didn't have to solder a short piece of copper and then put cap on that.
Also in post 10 you mention air blasts out the bottom hole, please don't put your body in front of 110 psi with suspected debris or shrapnel inside, but evidently that s not clogged. So it seems your describing everything normal , just gotta be sure the hot and cold are blasting through freely and not just one side

 

[Toshbu]

I had one instance where soldering on the vertical, solder had flowed downward and blocked most of the bypass channel. I wound up replacing the valve. I now solder those on the horizontal first whenever I can.

Thanks Terry! In this case, the shower worked fine for years. Then sat un-used for several years until I found it wasn't working. Changing the cartridge was my first step, and that didn't resolve. Then I started looking for ways to test the circuit and began my posting on your forum. Thank you for this forum. I've learned much and appreciate those who contribute!
Cheers!

 

[Toshbu]

Tosbu, in post #10 you mention about not seeing pipe sticking out bottom , I can't remember specifically which brands but they used to come with a plug in box to be used for shower only operation so we didn't have to solder a short piece of copper and then put cap on that.
Also in post 10 you mention air blasts out the bottom hole, please don't put your body in front of 110 psi with suspected debris or shrapnel inside, but evidently that s not clogged. So it seems your describing everything normal , just gotta be sure the hot and cold are blasting through freely and not just one side

Thank you for the safety advice Jeff! A very good reminder for sure. With your prompting, I will plan to test full flow without cartridge again. Do I simply place my finger inside the barrel over each of the ports (H & C) to determine if the flow is there?
When done initially, I did so by feeling the water that was coming out, however outside of the barrel, where I was able to feel distinctly both hot and cold.

Thanks again!