Detail instructions on how properly to ignite a gas water heater. See what types of ignition systems are available with pros and cons. Tips on how to relight a water heater if the pilot light goes out and what causes it. Common problems when igniting a gas unit.
Note: Do not try to light/relight a water heater if you smell gas. Leave a house and contact your gas supplier immediately. If you have issues with your unit, it is recommended to contact a plumber.
A gas water heater is an integral part of most homes in North America, heating water with natural or propane gas. They last over 10 years and come with warranties from 6 to 12 years. Over their lifespan, they can develop various problems. Some of these problems are easy to fix, especially for DIY-ers, while others, more complicated, require professional assistance.
While gas models share many elements with the electric variant, gas models are more complex and require more than basic knowledge and skills to service and troubleshoot.
Every gas-powered unit is equipped with a gas control valve that combines a gas valve, a thermostat, and an ignition system.
Gas valves are in charge of releasing gas into the combustion chamber when the thermostat calls for water heating. Water heaters use several types of ignition devices so users can manually or automatically light the burner:
The standing pilot or simply pilot light was the standard ignition type for many years (and it is still popular). The pilot light generates the small burning flame that is used to light the main gas burner. It works together with the thermocouple, which must be in contact with the flame all the time.
The thermocouple senses the heat, which creates a small electrical current. This is enough electricity to keep the gas valve open to deliver gas to the pilot light. For the water heater to operate correctly, the pilot flame must be ON, continually. The gas valve closes if the thermocouple doesn't register the flame.
Piezo igniters are designed to generate electric sparks and ignite the gas. Standard piezo igniters found in today's water heaters are push-button type and are built into the gas control valve. They do not require an electrical connection to operate.
Gas water heaters can also use hot surface igniters (HSI), resistance elements that are made of silicon carbide or silicon nitride. When a specific voltage is applied to the HSI, it starts glowing (orange to red, lighting the gas with the generated heat.
Today, most models are equipped with pilot lights and piezo igniters, while advanced models utilize hot surface igniters. Some older models do not have igniter buttons (you have to use a long matchstick or a BBQ lighter), which are considered manual.
Note: In some models, when a call for heating is initiated, an ignition system will try to light the burner several times. If the control panel doesn't detect ignition, a water heater locks out, flashing the corresponding error code.
Every gas device has a label with instructions on how to light a water heater attached.
Of course, there must be an unobstructed gas flow from the supplier and the main shut-off valve open.
Make sure that the tank is filled with water before turning ON the unit.
Note: The above instructions refer to a gas water heater equipped with the Honeywell gas control valve. The procedure might be similar for a model with different gas control valve types.
Note: If you couldn't light the standing pilot from the first try, repeat the process, but be careful as you don't want to release too much gas inside the combustion chamber and get unexpected results.
In the case of power vented water heaters, when the thermostat is satisfied, the burner shuts OFF while the blower keeps running for some time in the post purge mode. The unit stays in standby mode until the next call for heating.
If your water heater pilot light goes out, it won't be heating water, and you would miss a nice, long hot shower.
The procedure of relighting a pilot light is the same as explained in the text above.
Relighting a pilot is fast and easy, and as long as you don't smell the gas, it is safe. If you do smell it, leave a house and contact your gas supplier immediately.
Also, if it happens frequently, call a technician.
There are many reasons why a pilot light goes out, and here are some of the reasons:
If the standing pilot goes out frequently, you might want to check this article and these troubleshooting tips.
Keep in mind that when dealing with gas, it is always recommended to contact a PRO.
Proper maintenance is important to have all elements in good working condition and the water heater running with no interruptions. Check the main burner and ignition system at least once a year. Clean the debris and soot if needed, so as any deposits on the igniter/flame rods.