I have a shower/bath which doesn't stay hot. It has Moen fixtures. What happens is, when I run the hot water in the shower/bath, it gets hot/warm then goes cold for a while. It will repeatedly do this, giving a tepid to cold bath/shower.

Looking it up, I am seeing it may be a mixing valve? Does this seem right, and should replacing this be my first step? Is there a way I can be sure this is it, and if so, would this be something I could do myself? The sink in the same bathroom works fine (until you run the shower, then it seems to get the same problem).

Thanks.

 

How is the hot water from other fixtures in the house? Do they also run out of hot water?

Specifically what brand and model faucet are you having trouble with? There are many different brands and styles. Most modern ones have a simple balancing valve but some have other more "active" forms of temperature control.

 

Everywhere else in the house is fine. This only happens in this bathroom (we have 2) and when we run the bath/shower. It's Moen.