Troubleshooting Water Heater Pilot Lights

Important: Before troubleshooting any pilot light problems, keep in mind that pilot flame is always ON and the flame should be mostly blue. If it is yellow it needs adjustment. Also, make sure the tank is completely filled with water before lighting the pilot light.

Pilot Light Will Not Stay Lit

It is crucial that you read the manufacturer instructions carefully to prevent problems with the water heater pilot light; How to Maintain Gas Water Heaters and How to Light it. It is also important to understand when troubleshooting pilot light problems that gas heaters are equipped with the safety elements. There are many factors that can cause a water heater to not stay lit.

Here are some of the most common reasons:

• Thermocouple goes out
• Gas utilities being turned off
• Air temperature
• Lack of oxygen
• Defective gas control valve

1. All gas water heaters use pilot lights to ignite the main gas burner used to heat the tank reservoir. The pilot light plays a significant safety role as it ensures that any gas supplied to the main burner is ignited and not allowed to accumulate prior to the main burner is immediately ignited and not allowed to accumulate prior to combustion, thus creating a potentially dangerous explosion.

A thermocouple is a sensor used to measure temperature under a wide variety of temperature ranges and conditions and designed automatically to shut off the unit when the flame is not present or extinguished for any reason. The thermocouple stands guard over the functioning of the pilot light. It accomplishes this by continually monitoring whether the pilot light is burning and by providing an immediate “fail safe” by shutting down gas supply system when the pilot lights fail to burn, before uncombusted gas can accumulate at the burner head.

If the thermocouple connection is loose, tighten it. It should be embedded in the flame and tighten correctly, first hand, tighten and then use the wrench for an additional 1/4 turn. If you have the faulty thermocouple, replace it with a new one. The gas control valve should be creating at least 10 millivolts.

2. If there is no gas, or gas pressure is too high or low, check with your utility company.

3.  The air present in gas lines could prevent the pilot light from lighting. Purging the air from a gas line should be performed by a professional.

4.  Replace the thermostat, or gas control valve, if the inner elements are faulty or if the thermostat ECO switch is open.

Gas water heaters use two different elements to control the gas flow to the water heater. The gas cut-off valve is situated on the gas line leading into the water heater. The gas line feeds from the cut-off valve to the gas control valve assembly.

The gas control valve is part of the gas burner control module. This unit operates to control gas flow to the pilot light and as a thermostat by turning the gas to the burner off after water reaches the desired temperature. A thermocouple sensor detects when the temperature of the water drops and sends an electrical impulse to the thermostat control. The Thermostat causes the burner to light and bring the temperature of the water back up to the temperature setting on the thermostat.

Pilot flame is too large

The Main reason a pilot light is too large is if the gas pressure is too high. There is nothing you can do about this problem except to gall the gas utility company and check with them. The wrong size of the pilot burner orifice is another reason.

Pilot flame is too small 

You may experience the flame being too small if the gas pressure is too low. Check with your utility company about this problem. Also, the pilot light tube’s orifice might be clogged with the dirt found in the gas line. Some elements you can clean, but if there’s dirt on the incoming gas line, you should notify your utility distributor and check with the gas technician about installing the dirt trap in the gas line. If you have the wrong pilot burner, replace it with the correct one.

Pilot light will not light

One reason why you don’t have hot water is because the burner did not ignite. This happens when the pilot light does not light. Listed below are a few reasons.

1. If the pilot light is clogged, you should clean or replace it.
2. Faulty Piezo igniter. The water heater uses the piezo igniter to light the main gas burner and when pressed, it releases the electric spark. The spark gap is factory set. When Troubleshooting the light problems, it is recommended to test it first. Turn the gas OFF to the water heater and press the piezo igniter. Once pressed, the electrode should release the spark.
3. Check to make sure the wire connections are properly tightened.
4. Be sure that the electrode is not broken and replace it if it is.
5. If there is soot and/or carbon deposits on the pilot light, you should clean the tip of the electrode from the dirt, rust and other deposits by using a dry cloth and sandpaper.
6. No gas or faulty gas valve does not release the gas.

Pilot light goes out due to condensation  

Most of today’s water heaters will produce a certain amount of condensate. If there is excessive condensation, it will effect the light and extinguish it. In this extreme case, condensate is running down the flue tube and is dripping on the main burner, resulting in the pilot outage.

Pilot light goes out due to improper venting or air supply 

Improper venting will cause the pilot light outage on direct vent gas water heaters . Even a down draft from a ceiling fan or if there is a draft at the bottom of the unit, can blow out the pilot light. If there is a restriction on the fresh air delivery, find the reason and remove the obstructions. The proper air supply should be delivered when the unit is installed in a small, confined place. If there is wind blowing directly into the DV vent, it may cause the pressure imbalance.