On the side of most water heaters, you will be able to see a small valve and pipe system, known as the water heater pressure relief valve. This little device is vital for the maintenance of your water heater, as it prevents it from overheating, and becoming excessively pressurized. Without your water heater pressure relief valve, your heater can turn into a bomb which can even demolish your home.
What It Is
The water heater pressure relief valve can be found on the side of the heater, and usually consists of a short pipe, which is not connected to anything. You may occasionally find it dripping. This is the mechanism by which the pressure relief valve allows excessive pressure to escape. If you find that your water heater regularly leaks water in this way, you may need to replace the thermostat, or turn it down to a more suitable temperature.
What It Does
During times of considerable use, the water heater has a great deal of steam and moisture inside. This amount of steam increases the amount of pressurization in the heater. You may find that it rumbles or shakes, and this is a sign that it is near its pressure overload point. When it reaches this amount of pressure, the relief valve opens, allowing steam and moisture to escape, thereby relieving the pressure inside the heater.