What to Know About Gas Water Heaters

Most households have standard gas or electric tank-style water heaters. 

How it Works

A tank-type water heater warms cold water and keeps it warm until different household appliances and plumbing fixtures require it. The convection rule of physics governs how heat rises and how a gas water heater operates. Cold water is forced into the tank via a cold water supply tube to maintain a steady flow. A gas burner is situated underneath the sealed tank, heating the cold water at the bottom. The hot water discharge line draws the rising water from the tank as it becomes hotter so that it may be used wherever hot water is needed. The hot water discharge pipe’s function is to channel off the hottest water, so it is located at the top of the tank. 

A gas regulator assembly on the water heater’s side controls the gas burner that warms the water. A thermostat monitors the tank’s water temperature and switches the burner on and off as necessary.

Exhaust gases go up through the tank and out of the home via a chimney or vent pipe due to an exhaust flue that runs through the middle of the tank. To increase the appliance’s effectiveness, the hollow flue is equipped with a spiral metal baffle that collects and transfers heat nearby.

The Tank

A steel outer jacket encloses a pressure-tested tank. A glass or plastic covering lines a steel interior to avoid corrosion. Burner exhaust gases pass via a hollow exhaust flue in the middle of the tank and rise to an exhaust vent. The exhaust heat is captured by a spiral metal baffle within the flue and transferred to the tank next to it. Insulation between the inner storage tank and the outer tank jacket prevents heat loss. The hot water heater’s exterior may optionally be fitted with a fiberglass insulation tank jacket to improve the insulation further. 

Additional parts include a long dip tube that provides cold water to the tank and a shorter hot water output pipe that allows hot water to enter the plumbing system.

A metal rod, often made of magnesium or aluminum, will be present in glass-lined tanks. The anode rod attracts rust-inducing ions from the water to itself, protecting the metal tank from corrosion. Some types include a hot water exit pipe coated with magnesium or aluminum to act as an anode instead of a separate anode rod. 

The Pipes

Two water pipes are attached to the top of the tank. A shutdown valve manages the cold water supply line that delivers the cold water to the tank. Be aware of the location of the water supply shutdown valve so you can stop it when repairs are necessary. Since the pressure from the cold water entering the tank keeps the hot water flowing outward, turning off the cold water supply stops all water flow. The hot water output line, which distributes hot water to all of your sinks, tubs, showers, and appliances that need hot water, is the operational end of the hot water heater.