How do you replace the pressure relief valve on a water heater?

To replace the pressure relief valve on a water heater, first, turn off the power and water supply to the heater. Allow the water to cool down. Next, locate the valve on the top or side of the heater and unscrew it using a wrench. Replace it with a new valve of the same size and pressure rating. Finally, turn the water and power back on and check for leaks.