How To Turn Off Hot Water Heater Water Supply. (4) shut off the cold water supply to the hot water tank. (1) for working on water pipes or draining the tank, turn the gas valve control to pilot.
If you have a hot water cylinder with a cold water storage cistern. For ball valves, turn the lever clockwise 90 degrees. When you get home, you’ll be without hot water and might run into issues with turning the unit back on.
To turn off the gas supply to the water heater:
The guaranteed issue will be that your water heater will take a long time to heat the tank water back up. That being said shutting down the water supply can change the pressure in the system as temperatures of the water change. Turn the water supply off. A water heater has one or two thermostats depending on the size of the water heater.