Shower type mixer valve inside sink cabinet???

[FONT=Comic Sans MS]I came across something unknown was hoping someone may have an idea what it is and its function. During my inspection of the master bath, when inspecting inside the sink base cabinet I observed what appeared to be a single handle shower mixer valve mounted on the back wall inside the cabinet. The sink faucet above had the typical hot and cold control knobs and operated normally, even when turning the mixer valve no changes seem to occur. I am puzzled as to what this is. The home was built in 2012 and has PEX plumbing if that make any difference.[/FONT]

What kind of faucet did the master tub have?

Both the master and hallway bath used the same type of single handle control mixer valve in the showers

I’ve never seen that before.

Did the master TUB have a single handle faucet or two handle?

As mentioned above both the master and hallway bath used the same type of single handle control mixer valve in the showers.

I’m totally puzzled…

Also noted the valve only turns and does not pull in and out as with the shower mixer valves

Ask the owner?

Master tub???

The home was unoccupied, owner pass away…

Wanted to be sure that we were both taking about the same thing. I thought that it was going to turn out to be a poor approach to meeting the temperature limiting device requirement for two handled tub faucets that was introduced with the 2012 IRC.

The solution often involves a mixing valve installed under the master sink

Apparently it’s not.

Had one of those today.

[FONT=Comic Sans MS]I suspect your most likely right that it may have something to do regulating hot and cold, but for what. For all I know it may turn on a fountain in the back yard. [/FONT]

Just weird.

For an exterior hose bib. Can’t wash the car with cold water.

Gary’s in California. I don’t think your allowed to use water to wash the car, period. :mrgreen:

Maybe they wanted to control the maximum hot water temperature at that sink in particular for some other reason.

During the inspection I turned the valve all the way to one direction, then tried all the fixtures in master bath, then I turned it the other direction and once again tried all the fixtures, I could not see any difference.

That’s a plumber just messing with us. Just strange. Must control temp to something, outside faucet, tub,…

Here is my wild theory…here in NH I sometimes find hot water supplied to a tempering/mixing valve that supplies water to the toilet tank. Warm water in the tank keeps the tank from sweating during our humid periods. I don’t know your climate out in Cali but could it be a temperature control for the toilet water.