Just because it doesn’t have temperature markings doesn’t mean it can’t maintain a constant temperature (selectable from a wide band). These are mechanical devices without any electronics. They work by maintaining the pressure ratio you set between the hot and cold supplies. When they seize up they become “100% cold or 100% hot, no in between” devices. In other words, a cold/hot toggle switch.
Just because it doesn’t have temperature markings doesn’t mean it can’t maintain a constant temperature (selectable from a wide band). These are mechanical devices without any electronics. They work by maintaining the pressure ratio you set between the hot and cold supplies. When they seize up they become “100% cold or 100% hot, no in between” devices. In other words, a cold/hot toggle switch.
My apartments hot water supply is really hot, so the band is still pretty narrow.
All hot is about 60° C, so you need comparatively little hot water, at least in relation to every other place I’ve showered…