WATER HEATER WARM WATER NOT HOT

Check this out....

https://www.youtube.com/watch?v=IsiXaMEneaY

Check your heater bypass valves

The the burner comes on,doesn't make the water warm

then the thermostat if you hear the burner come on. IF burner does not come on either control board or gas valve

Gas water heater,the outside shower is turned off under the sink

If you have an outside shower, make sure it is turned off at the faucets. The hot and cold will mix if it is only turned off at the head.

Perhaps a little more information. Like on gas or electric. Do you see or hear the burner ignite. Have you checked the thermostat do you have an outside shower and could one of the faucets be open with the shower head off this might allow bypass.