When we shower we find that the hot water tap will slowly shut itself off - though it never turns off completely. If we turn on the hot water until the tap is warmed up first, it sometimes helps but not all of the time. It didn't used to be like this and we can't figure out what to do to correct it. We have a gas hot water heater which is located directly behind the tap of concern. This is a shower in the tub, and the taps have been replaced with new ones, with no benefit from doing that.

What's the brand name of thr valve? Regards, tom

You may have high water pressure problem combined with very easily going stem. Measure your house pressure first... It should be around 45 to 55 psi.