My shower's temperature is really getting out of control. When I start the shower it is now almost impossible to get the exact hot water temperature I have been using for years. The water is either scalding hot, luke warm, or cold; there is no usable hot. After the shower runs for a while the temperature I am looking for finally becomes available. Later the temperature seems to change by itself and I then have to constantly readjust the temperature. I am assuming that change is due in part to less hot water in the water heater. One solution that has been working for a while has been to almost completely shut off the cold water valve in the shower. Doing so has, surprisingly, allowed for a wider range of temperatures. That fix seems to be working less often, however, it is still working better than setting the cold and hot water valves at equal levels. I have my water heater turned up to around 145 degrees, so when this began I thought maybe that has something to do with it but I seriously doubt it because turning down the cold water valve in the shower seems to have helped. We also do not have any thermostatic valves installed anywhere. The problem also occurs intermittently around the rest of the home (kitchen and bathroom faucets). Also, it takes quite a while for the hot water to come through kitchen and bathroom faucets. Anyone run into this problem before? Any fixes?