Mixing valve in shower

[jneiberger]

From time to time, when I get up to shower in the morning the water

doesn't get as hot as it should. I can turn it all the way to hot but it's still not as hot as I'd like it. On most days, I'd get scalded shortly after turning it all the way to hot. I used to think this was because of our water heater, but I just replaced that a couple of days ago because it sprung a leak. Is the next likely culprit the mixing valve in the shower? Could it be corroded or gunked up or something? I know nothing about them but I can't think of anything else that could cause this problem.

Thanks, John

[RayV]

Any idea what model valve you have? I have an old Delta that you take the knob off and there is a 'limiting wheel' that you can reposition to get more hot water. Some have a screw under the knob to adjust the 'max hot'.

[Malcolm Hoar]

Rather likely. Do you have normal hot water at the closest regular faucet (e.g. nearby sink)? If so, it's almost certain the shower mixer.

[colinberry1]

If you don't have a thermostat valve, but only a manual hot and cold taps it would be probably difference in water pressures.

Try turning on the hot only and gradually feeding in the cold.

[e-mail] wrote:

[jneiberger]

This is the sort of valve that starts out cold and gets hotter as you turn it counter-clockwise. There's only one knob, unfortunately. I'll have to look and see what model it is. I can probably find a replacement at Home Depot or Lowe's, if that's the problem.

I've never taken one of these apart before. Is this a pretty easy job or can it be tricky?

[krw]

Moen single knob mixing valves tend to fail this way. AIUI, the cartridge develops a leak from the cold side to the hot. I'm told a bad Moen valve anywhere in the house can do this to the entire system. I have one that needs replacement, but other more pressing things first.

They have a lifetime warranty so if it's a Moen you might try calling them.

[Pat Coghlan]

[jneiberger]

I have no idea what brand it is. There are no markings on the outside that provide any clues. I'm sure it was the cheapest valve available when the contractor built this house six years ago.

What's weird is that it's very intermittent. I can have very hot water for many days and then have one or two days where it doesn't get much past warm. Very strange.

[colinberry1]

[jneiberger]

I looked a little closer and see that it is a Moen. They must not be proud of it, though, because the lettering is very tiny. :)

[colinberry1]

Here is a link for you. There is an acrobat reader file, name "parts" below, download it so you will get an idea, of what a "Thermostatic Cartridge" looks like, that you will have to replace, don't let the diagrams intimidate you because if you print a copy and remember the sequence you remove each part by numbering it on your printed copy.

What you will have to do is to find the correct model that you need on their Web site or phone them for help.

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