Water Heater Replacement Most problems with a water heater can be fixed without calling a plumber. In most cases, you will need to replace your water heater instead of repairing the existing one. If the water heater has an electrical problem or is very old, it might be best to replace the entire unit. You might want to replace your water heater if: Water is slightly cold when turned on . If the water temperature is still too high after turning on the hot water, the first thing to check is the heat setting's adjustment switch. It may be too low, or it may have been worn out. Suppose the water temperature takes a while to get up to an average temperature after turning it on. In that case, the water heater may not regulate temperatures, and the thermostat is probably broken. The drain in the tub is clogged with mineral deposits and hard deposits . These minerals will cause your hot water to come out a bit cold. Sometimes this problem can simply be cleaned out by using some chemica...