I'm fairly mechanically inclined, so this one has me for a loop. The shower worked fine the day (and years) prior. Next morning, I go to turn on the shower (single handle Moen) and the water only trickled out the hot side. The cold side has the normal pressure, hot side, a very small flow (trickle?). Ahhh Ha, I think I know this one. I need a new cartridge. Go to Home Depot, get the new cartridge, pull out old one, put in new one and... same thing, trickle of hot water. I turn off water to house again, pull new cartridge and inspect valve. Valve is a simple hot side, left side, shower riser (no pressure regulator, stop valve, etc). I look down the cartridge opening and it looks clean. I even gently take a brass hanger and snake it down through the hot water opening for about 3-4 inches, to see if there is an obstruction. Nothing. I then turn the main water back on for a few seconds to flush any debris (i.e. water shoots through open valve causing a little bit of a mess). I put the new cartridge back in and... again, no hot water. Hot water pressure is good to the sink in that bathroom and every other area of the house.

So, I believe there is a clog somewhere in the section of pipe that goes to the shower. It can't be something that built up over time or it would have gotten slower over time. Is there a device to "snake" a 1/2 inch brass pipe like a drain auger? Anything else I should consider? Thank you.

When you turned the water on to "flush any debris" from the line... was there full pressure from the hot.. If not then look for a shutoff to the hot water line of the shower (could be behind wall not readily accessible). Use a mirror and a flashlight to look down, inside the wall and see if you can see shutoffs.

IF you had full pressure after flushing the water line then I can only surmise that you have a defective cartridge replacement and will need to go get another one... though this rarely ever happens.

A few guys that really seem to know faucets are Doug238, Iamgrowler, and of course, speedball1 (I am sure I am forgetting a few... sorry guys! )... check with them by private message if you need too... seems they know shower valves a little better than me ( I won't admit that again.. *wink*)

Anyway, good luck.

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Well, I think I solved it, but don't understand the "why" behind it. In answer to massplumber2008 above, it was difficult to see if the pressure from the hot was the same, but I noticed the water was cold, so I could only assume there was a clog down the line from the valve. I devised a way to "unclog" it by routing the cold water inlet directly to the hot water inlet. I did this by taking the old cartridge and using duct tape to cover the spigot holes. I also turned of the hot water heater cold water inlet and opened the relief valve. I reinsterted the block cartridge, put water back on, and then pulled the valve open equal hot/cold. What this did was allowed the cold water to go full pressure through the cartridge (which was blocked from coming out the main spigot) and go through the hot water side (hopefully blowing any debris out). The pressure was allowed to back through the system into the hot water heater.

When I reversed everything, put the new cartridge back in... viola I had full pressure hot water! Well, this lasted about 30 seconds until I heard a "kaaathunkkkk!" I did the back flow again, reinstalled, and again, 30 seconds of fast hot water until "kaaaathunkkkk!

Now I had to cut. I went around to the wall behind the shower. I cut a hole in the wall to see what I was dealing with. I noticed the hot water inlet to the valve had a 12" riser that was capped off. I remember somewhere this was there to stop "hammering" but I began to wonder if air was being trapped in that area stopping water pressure from going to the valve. Not knowing much about it, I reached into the hole with vice grips and clamped the riser about half way up. Look, I was desperate, and had already started cutting holes. I went back to the shower, and the hot water has the old pressure and doesn't go "kaaathunkkk" anymore. I also don't hear hammering. So, I don't know what I did, but it seems to work. Took a shower with it this morning... does anyone know what the problem was??

NOPE... *laugh*... not likely that it had anything to do with clamping the bumper. BUT does not matter at this point.. it works! I imagine you flushed something out of line or the cartridge finally seated. Glad you are up and running again!

I would say that you have a drop of solder in you hot water line. When soldering copper, if too much solder is used it can run inside the pipe. Some times it forms into little round beads. Some times it falls, hits a cold surface and splatters into little flat thin wafers. Water movement later carries this solder to the next available valve, where, being to large to pass it blocks the port of the valve. This can take years. When you back flushed you move the solder back into the pipe (neat idea to back flush). Since it doesn't sound like you have a stop valve on this line it probably was lodged in the shower valve. Don't worry, it will come back. May be years but it will. When it does cut the line near the valve, back flush then reconnect the line.

Great point. What you are describing sounds correct. For the first few tries, the hot water would run and then I would hear something close shut inside the pipe. I was thinking either a pressure lock or some type of debris. Loose solder sounds like a prime suspect. If it happens again, I will cut and flush. Thank you.

I have similar problem - still have it - Moen pull on type shower valve wiith a 1125 cartridge. Pull on and then nothing. Had this happen before but went away on it's own. Yesterday it quit again no water hot or cold not even a drip.
Put in new valve.
No water.
Took out valve pondered if I had in wrong.
Put back in , no water.
Took valve/cartridge back out
Turned on water supply
NO WATER out of the empty hole
Took out the balancer or whatvever it's called - the thing under the large screw had that nearly could't get loose.
Turn on supply
NO WATER AGAIN
Removed both small shut off assemblies
Turn on Supply
NO WATER AGAIN
Put everything back together
New cartridge very smooth - no water
Left in on position hope it cures itself
Looks like only thing left is to have plumber come cut the lines on basement and back flush with high pressure air.
What a crock.

Hello Livingina,

You posted your problem in 5 years thread which it may be closed by now, please open a new thread of your own that it will have more visibility and one of the experts will respond to you, always check the date on left top corner of the post, good luck.

John

Had this happen before but went away on it's own

When that happened was it winter time?


Yesterday it quit again no water hot or cold not even a drip.

How cold is it now where you live?


Removed both small shut off assemblies

That sounds like integral stops (stops that are part of the valve assembly)


Left in on position hope it cures itself

You are an optimist aren't you?

As I read your post you got no water, hot or cold, with the cartridge removed. Neither did you get any water with the stops open up, whether they are integral stops of separate stop valves on the lines.

The chances of both hot and cold lines being blocked by some debris at the same time are slim and none.

You mentioned pipes in the basement which implies that all piping should be in heated areas.

If this occurred in the past during cold weather and if it is very cold now where you live, I would say that these pipes pass through an exterior wall and are freezing.

It started working . Left on for hours. I think you are right. Heated foamed basement , pipes very close to outside wall, up near the floor joist rim joist area pocket - found some cold are flow in that section - will manually foam the air leak.
Still glad to have the silky smooth new carttridge in plus the learning experience.