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Article Originally Posted on WaterHeaterStore.co
Gas Water Heaters


Gas water heaters come in all shapes and sizes. If you’ve been around long enough, you’ve likely seen all kinds of colors and unique designs. But most gas water heaters have basic components that are all the same. The systems work very similarly, even if the parts are very different.

In this article we’ll walk you through the anatomy of a gas water heater and basic components. Understanding the basics of the design can help with all forms of troubleshooting and problem-solving.

Gas Water Heater Systems

Gas water heaters have several basic systems that make them function and these systems are common to nearly all tank-based water heaters:

  • Water tank
  • Heating elements
  • Water intake/output
  • Safety systems

Depending upon the age of the gas water heater, the biggest differences are the sophistication of the safety systems and the controls.

How Gas Water Heater Work

Let’s take a quick look at how gas water heaters make hot water. This is important to know so you can do a quick fix or troubleshooting checklist.

  1. Cold water is pumped into the water reservoir/tank
  2. Heater turns on at the bottom of the tank
  3. Hot water rises to the top
  4. Cold water circulates to the bottom of the tank where it is heated
  5. Hot water is pulled from the top of the tank to supply heated water

Pretty simple, right? Now lets look at the components to see just how each general part functions in this process.

Gas Water Heater Tank

Tanks have evolved to be more efficient than ever for storing hot water. The more efficient the tank, the less you’ll have to reheat the water to keep it hot.

The tank is also your biggest bottleneck if you need lots of hot water. If you find that you are running out of hot water fast, you may need a larger tank, faster recovery (the amount of time it takes to reheat a tank of water) or possibly to turn the thermostat on the water heater up a bit.

Gas Water Heater Heating Element

The gas water heater uses a burner underneath the tank to heat up water. Gas, whether natural gas or propane, is piped to the burner where it lights up – and much like a gas stove – heats the water.

A temperature regulator (consisting of a thermostat and switch) connects to the gas burner to help control how much gas is burned. The more gas, the hotter the water.

Gas Water Heater Intake/Output

There is typically a simple system of two water pipes running into any gas water heater. The one at or near the bottom of the tank is the cold water intake. This feeds directly from a cold water line into the base of the gas water heater where the water gets heated.

Near or into the top of the gas water heater is the hot water output. This pumps the hot water throughout the building.

Gas Water Heater Safety Systems

Again, this will depend on the age of your gas water heater, but all modern gas water heaters have a series of passive and automated safety systems. You want passive safety systems in place in the event that the gas water heater loses electricity, but not gas. This prevents the gas water heater from heating the water up to dangerous temperatures because the automated safety systems are not functioning.

Passive safety systems in gas water heaters typically involve a pressure relief valve. If too much pressure builds up in the gas water heater then the pressure is relieved by the valve opening and releasing water and steam. Too much pressure can build up either by too much pressure in the cold water supply or by the water heating up too much.

Automated gas water heater safety systems use a thermostat to will shut off the gas when the proper water temperature is reached. The thermostat is connected to the heating element.

Knowledge of Basic Gas Water Heaters

Knowing these basic principles about gas water heaters, whether natural gas water heaters or propane water heaters, will help you to maintain and service your own gas water heater system.