Why does my shower water temperature gradually get cooler?

[rhliberman]

When I set the water temperature before stepping into the shower, within a minute or so I can feel the water getting cooler. I have to continuously keep increasing the hot water.

I have plenty of hot water, the temperature just will not stay constant.

This only occurs in the master bathroom, not the others.

Thanks

[patrick88]

What brand is the valve? Do the other fixtures in the bathroom have problems?

[fidodie]

your expansion tank is in a warm area, and the water coming from the water main is colder and mixing with it. the result is the cold water gets colder. This assumes you have a well, and expansion tank and the well is kicking in.

other possibility is your dip tube on your water heater is broken off.
cold water gets into the top of your water heater, instead of the bottom...here's a visual.



it directs cold to the bottom, and pushes hot out the top...

condo/apartment or home? well or city service?

[rhliberman]

What brand is the valve? Do the other fixtures in the bathroom have problems?

I replaced the compression valves myself a couple of years ago. I picked up the valves from a local plumbing supplier. Knowing me, I must have done something wrong - so, it could be the valves?

[rhliberman]

your expansion tank is in a warm area, and the water coming from the water main is colder and mixing with it. the result is the cold water gets colder. This assumes you have a well, and expansion tank and the well is kicking in.

Thanks, but since this only happens in the master bathroom I don't think it's a water heater problem.

[fidodie]

My Bad - missed that last line......