3 Reasons Your Gas Water Heater's Burner Won't Ignite

Conventional storage water heaters are surprisingly simple appliances. If your water heater uses gas as its fuel source, it relies on a burner to generate heat. In a typical design, you will find the burner at the bottom of the tank, and exhaust from the combustion process travels up a flue. Along the way, a heat exchanger extracts warmth from the combustion gases and transfers it to the water in the tank.

Since this entire process relies on the burner, it must ignite whenever the temperature of the water in the tank falls too low. The thermostat on your water heater detects changes in water temperature, signaling the burner to engage as needed. If the burner refuses to ignite, it may be due to one of these three common causes.

1. Pilot Light Problems

Old-style gas waters (and gas appliances in general) use a standing pilot light to ignite their burners. A standing pilot light continues to burn, even after the water temperature has reached its set point. The purpose of the pilot light is to jumpstart the whole process by providing a flame to ignite the gas. If the pilot goes out, this style of water heater will be unable to ignite its burner.

Sometimes, you can relight a dead pilot light, and your gas water heater will continue to function normally. In other cases, the pilot light has failed due to an underlying problem. Common issues with pilot lights include clogged gas valves and faulty safety devices. If you cannot ignite your pilot light by following your water heater's instruction manual, contact a professional.

2. Electric Igniter Issues

Pilot lights can be inefficient since they require a small trickle of gas even when the water heater isn't in use. This has led most newer units to use electric igniters. These designs typically use a high-voltage spark to ignite the flow of gas. If the igniter fails, then the burner cannot ignite, and your water heater won't be able to turn on.

Although the method is different, these water heaters still rely on a flame sensor to confirm ignition. If the flame sensor is faulty, then your water heater won't ignite at all. This behavior prevents your water heater from continually releasing gas when the burner is not running.

3. Burner Failures

If the issue isn't with the ignition system, then it may be with the burner itself. Burners can fail for several reasons, and a burner that's inefficiently operating may leave unburnt fuel on its surface. In some cases, thoroughly cleaning the burner unit can help to restore it to proper operation. If cleaning does not help, and the ignition system is working, then you may need to replace the burner assembly.