Anatomy of a Gas Water Heater

You’ve no doubt turned the water on in the shower to have what feels like pins of ice descending upon you. When the pilot on the hot water heater goes out, everyone suffers. The anatomy of a gas water heater is actually rather straight forward. Most homes have what is called a “tank style” heater. A tank style heater takes cold water, heats it, and stores the warm water for use.

Any child can tell you to stop drop and roll because heat and smoke rise. This is exactly what your hot water heater does. Physics states that hotter materials will rise. In a tank style heater, a gas burner is located at the very bottom of the heater. Cold water is supplied to the tank through a cold water supply line. Controlling this cold water source is the shut off valve. If you ever need to shut off your water source, you would use this valve to do so.

Cold water is then injected into your water heater near the bottom, through a dip tube, the water is essentially boiled. The hot water rises to the top of the tank at the hot water discharge, and more cold water enters in it’s place. Supplying hot water to your home is the hot water line.

A hot water heater is made of steel and encased in an insulation to maintain hot water temperatures. If you were able to saw the top off your tank, you would see the dip tube that supplies cold water. If you tank has a glass lining, you will also see a metal rod made of magnesium or aluminum which is called a sacrificial anode. This metal rod draws corrosion to itself so it doesn’t stick to the sides of the steel tank. If your tank is wrapped in plastic, the sacrificial anode is usually not present.

At the very bottom of your heater is the gas burner responsible for heating your water. The gas is supplied to the tank by a pipe. If you ever need to shut off your gas source, there is a shut off valve attached to this pipe. The gas burner control module is what controls the temperature of the water, and is responsible for igniting the pilot light. You will know if your pilot light is lit if you see a small flame with blue tips about 1/2 inch high.

At the very top of your hot water heater is the gas combustion exhaust flue. This flue captures excess gases and keeps the water heated at a constant temperature. If you are putting in your own water heater be aware that there are very strict guidelines for the flue.

Also at the top of the tank is the pressure relief valve. The name is indicative of it’s responsibility. If hot water causes too much steam or pressure to build, the valve will release this extra pressure maintaining a safe operation level. It operates much like the radiator cap does for your car.

Last but not lease, near the bottom of your tank is a tank drain valve. Although our water is purified, it still has chemicals and sediment. Without a tank drain valve, this sediment would build up in the bottom of our hot water tank. The tank drain valve ensures that our water is fresh and your tank operates optimally.