No Hot Water Pressure in Shower (not the valve)

[Vdeloren]

I have a shower in one of my bathrooms that has absolutely no hot water pressure what so ever. Pipe is 1/2 copper with a moen single handle shower valve from 1955. I have just replaced the valve assembly and still have no hot water. The interesting part is that same hot water line goes to the sink in the bathroom and the sink has great hot water pressure. Last night I shut off the cold water to that bathroom and left the hot on. I removed the shower valve from the brass casing and not a single drop of water came out, hot water still flowed from the sink. Is it possible that the hot water line is completely clogged somewhere after the T joint? The setup is like this (sorry for the crude illustration):

shower sink
| |
__________|___________|

 

[hj]

Possibly, but more likely you have a Moentrol valve with a stuck pressure balancing spool. Remove the round trim plate and see if you have a large "nut" with a screwdriver slot in it to the right side of the valve. If so get a new one and then replace it. It will probably come apart when you unscrew it and then you have to work at getting the piece left in the valve removed.

 

[Sponsor]

 

[Reach4]

If so get a new one and then replace it. It will probably come apart when you unscrew it and then you have to work at getting the piece left in the valve removed.

You are an Ipad user?

 

[Jadnashua]

The pressure-balance function on most shower valves is designed to shut off when you do not have pressure on both sides, so with the cold off at the supply and only hot going in, it should not have passed any hot - that part was working properly. As HJ said, though, that pressure-balance valve can become stuck and reduce the flow all the time if it doesn't return to center.

 

[Vdeloren]

Here is a pic so just remove that top nut and replace?

 

[hj]

yes.

 

[FullySprinklered]

Looks like my ex-wife's chicken pot pie. Probably tastes about the same. She put Delta in hers.

 

[Vdeloren]

I removed that spool and it came out easily and looked like it was in pretty good shape. I put it in a vinegar water solution and added a little grease to the inside spool so that it was moving freely... Still absolutely no hot water. I then removed both the spool and the valve, shut off the cold water to that bathroom and turned the water back on. Still not even a trickle of hot water coming from the valve. Is it safe to say that there is some type of occlusion in the pipe past the T joint either at the joint or where the hot enters the brass valve assembly? I purchased this house about a year ago and have been renovating other rooms, it is possible this shower has not been used in 2-3 years.

 

[hj]

Remove that "gunk" around the valve, because you probably have "integral stops" on the valve and the hot one is closed.

 

[tchannell]

I have a moentrol with a balancing spool. I have replaced the cartridge and the spool (twice) with both of them out I have great pressure. When I put in the spool I have very low cold pressure but great hot pressure. I have cleaned the base and still low cold pressure.

 

[CountryBumkin]

This picture/diagram may help

1 Check Stops Spring-driven gaskets at the valve inlets prevent high-pressure hot water from crossing the valve into a cold supply line or vice versa. (Hot water is at higher pressure in recirculation systems.) Screws in the stops shut off hot and cold lines at the shower for work on the valve cartridge.

2 Pressure-Balancing Spool Hot and cold streams slide a graphite-composite piston in response to fluctuating hot and cold water pressure. In 0.1 seconds, the piston (inside the chrome sleeve) seals or opens inlets to maintain balanced pressure between the two flows, which are still unmixed. Lab tests to monitor internal movement show the piston constantly vibrating back and forth.

3 Cartridge Pulling the shower handle slides the cartridge forward, opening two inlets to let hot and cold water enter and converge. Turning the handle opens one inlet as it closes the other, allowing users to adjust the temperature.

4 Temperature Limit Stop Screwed into the cartridge's rod, this stop prevents a child from fully opening the valve to a scalding-hot setting

 

[tchannell]

I was unable to open the file. Thanks for the diagram though