Cause 1

Thermocouple

The thermocouple detects the pilot flame. If the thermocouple does not detect a flame, the ignition process will stall, and the burner will not light.

Cause 2

Pressure Switch

The pressure switch closes when the proper airflow is achieved, signaling the control board to continue the ignition process. If the pressure switch is defective, the ignition process will stall, and the water heater will not light.

Cause 3

Igniter

Some water heaters use an igniter to ignite the gas. If the igniter fails, the burner will not light. To determine if the igniter is defective, first make sure the igniter is getting voltage. If the igniter is getting voltage, but it doesn’t glow, this indicates that the igniter is defective and should be replaced.

Cause 1

Drain Valve

The drain valve can be opened to drain the water heater for maintenance or to flush out mineral deposits from the tank. If the drain valve is leaking, drain the tank and replace the drain valve.

Cause 2

Temperature and Pressure Relief Valve

The temperature and pressure relief valve opens to stabilize temperature or pressure of the water heater if the temperature or pressure exceeds the proper level. The temperature and pressure relief valve opens at a set temperature. This temperature is indicated on the water heater. If the temperature and pressure relief valve leaks even though it has not reached the indicated relief temperature, replace it.

Cause 1

Thermostat

The thermostat determines the maximum water temperature setting. If the thermostat is defective, the water temperature may not be set at the proper level. To determine if the thermostat is defective, assess hot water temperature from the nearest faucet. If the water temperature is hotter than the selected thermostat setting, this indicates that the thermostat is defective. If the thermostat is defective, replace the thermostat. We recommend a set temperature of 120 degrees or fewer to prevent the risk of scalding.

Cause 2

Heating Element

If the heating element is shorted out, it will heat continuously, causing the water to get too hot. To determine if the heating element is shorted out, use a multimeter to test if the element is shorted to ground. If heating element is shorted out, replace it.

Cause 3

Gas Valve and Thermostat Assembly

The thermostat determines the maximum water temperature setting. If the thermostat is defective, the water temperature may not be set at the proper level. To determine if the thermostat is defective, assess hot water temperature from the nearest faucet. If the water temperature is hotter than the selected thermostat setting, this indicates that the thermostat is defective. If the thermostat is defective, replace the gas valve and thermostat assembly. We recommend a set temperature of 120 degrees or fewer to prevent the risk of scalding.

Cause 1

Gas Valve and Thermostat Assembly

The gas valve opens to allow gas to enter the burner. If the gas valve does not open, the burner will not light, and the water heater will not heat. First, ensure that the ignition source is working properly. Second, ensure that the gas valve has pressure. If the ignition source is working, and the gas valve has pressure, consider replacing the gas valve and thermostat.

Cause 2

Pilot

The pilot ignites the water heater’s gas burner. If the pilot does not light, the water heater will not heat. Sometimes, carbon deposits can build up on the pilot and eventually create a restriction. If the pilot is restricted, try removing it and clearing it with a stiff brush and/or compressed air. If the pilot cannot be cleaned, replace it.

Cause 3

Thermocouple

Some gas water heaters have a thermocouple. The thermocouple detects the pilot flame. If the thermocouple does not detect a flame, it will prevent the gas valve from opening.