The shower is upstairs and worked fine this summer. Now we have a guest trying to take a shower and there is no hot water pressure or much hot water coming out of the faucet. We have a single dial for the temperature adjustment and a valve on the spiket to turn the shower on. Both sinks in the bathroom have hot water coming through them. We checked the valves under the sink and they are both turned on. We don't know where the valve for the shower is. Is it behind the wall so you have to tear out the wall to find it? The house is only three years old and that shower doesn't get used very ofen.

Hi Janice...

Sounds like something is clogging up the hot water inlet to the cartridge of the shower valve.

Here , you probably won't find shutoffs for the shower so you'll need to shut the water off at the water meter or if on a well, at/near the expansion tank. This will also shut the hot water off as cold water feeds the hot water system.

Once the water is shut down you need to remove the trim plate at the valve and gain access to the cartridge inside. Remove the cartridge assembly and inspect/clean it well. Now, while the cartridge is out cover the valve with a towel and have a friend PULSE the main water supply back on for a few short bursts to clear the lines of anything that could be blocking the hot water valve inlet.

Reassemble and check your work... hopefully improved!

If no improvement then you will probably need to replace the cartridge brand new or could have other issues so let us know what you discover, OK?

Questions?

Mark