Shower mixing valve –All showers have a mixing valve that combines hot and colder water supplies. If you’re only getting cold water, start by ensuring both water supplies are turned on all the way. If they are, you may need to replace the mixing valve. What if There’s No Hot Water...
check that all shutoff valves are fully open and verify the water pressure with your water supplier. For low hot water pressure only, inspect for partially closed valves, mineral deposits, or blockages in the hot water pipes. Clean or replace clogged shower heads and faucet aerators if needed...