Gas hot water heaters are relatively simple in their construction. The gas valve and pilot light sit below the heating element, which is located at the bottom of the water storage tank. A single thermostat is located inside of the tank, monitoring the temperature of the water that is being stored so that the heating element can be turned on and off as needed. Two water lines are connected to the hot water heater, with a cold water line bringing water into the tank and a hot water line taking water out.
Gas Hot Water Heater Construction
Gas hot water heaters are relatively simple in their construction. The gas valve and pilot light sit below the heating element, which is located at the bottom of the water storage tank. A single thermostat is located inside of the tank, monitoring the temperature of the water that is being stored so that the heating element can be turned on and off as needed. Two water lines are connected to the hot water heater, with a cold water line bringing water into the tank and a hot water line taking water out.
Detecting Water Temperature
The thermostat in a gas hot water heater is used to detect the temperature of the water held within the water heater's tank. By monitoring the temperature, the water heater can heat cold water as it fills the tank or stop heating the water once a specified temperature has been reached. This is especially important as hot water is used, as the water which replaces it in the tank will be significantly colder and will begin lowering the overall temperature of the water that is being held in the hot water tank.
Controlling Gas Flow
When a gas hot water heater's thermostat detects a drop in water temperature that puts the water in the tank below the water heater's minimum temperature, it activates a circuit to increase the heater's gas flow to warm up the heating element in the tank. If the temperature of the water reaches the upper limit that the thermostat is set to, it will break the circuit to decrease the gas flow and let the heating element begin to cool. It should be noted that even when the gas has been turned off, the pilot light will continue to burn; if the pilot light is extinguished, then a safety mechanism will prevent the gas valve from opening again until the pilot light has been re-lit.
Thermostat Adjustment
Most water heaters are designed so that the thermostat can be adjusted manually using a dial or screws located on the outside of the water heater unit. In most cases, users can adjust both the upper and lower limits of the water heater, determining the point at which the gas turns on and off in order to maintain a desired temperature. It is recommended that the minimum temperature of a water heater be at least 130 Fahrenheit degrees in order to avoid bacterial growth within the tank, though some users may prefer to keep their tank closer to 140 Fahrenheit degrees. The temperature dial or screws to the thermostat of a gas hot water heater are generally located near the bottom of the heater close to the heating element, though in some cases they may be concealed beneath a panel.
