Troubleshooting pilot light problems on gas water heaters. How to fix the water heater when the light goes out, does not light, won't stay lit, pilot flame is too small or too large.
It is important to understand when troubleshooting pilot light problems that gas heaters are equipped with the safety elements, such as thermocouple, that are designed automatically to shut the unit off when the flame is not present or extinguished for any reason.
Most of today's energy efficient water heaters will produce a certain amount of condensate. If there is an excessive condensation, it can affect the light and extinguish it. Condensate, in this extreme case, is running down the flue tube and is dripping on the main burner, which results in the pilot outage.
Most of the time improper venting will cause the pilot outage on direct vent gas water heaters. A down draft from the ceiling fan or if there is a draft at the bottom of the unit, can blow out the pilot also. If there is a restriction in the fresh air delivery, find the reason and remove the obstructions. The proper air supply should be delivered when the unit is installed in the small confined space. If the wind is blowing directly into the DV vent it may cause the pressure imbalance. If the water heater is installed in an attic, an excessive heat (above 120 C) could be another reason.
One of the reasons why you don't have a hot water is when the burner did not ignite, and this is happening when the pilot light does not light. And here are the reasons:
When troubleshooting pilot light problems such as when it does not stay lit, keep in mind that there are often different causes for this and other conditions.
The main reason why the flame is too large is if the gas pressure is too high. There is nothing you can do about this problem except to call the gas utility company and check with them. Another reason is the wrong size of the pilot burner orifice.
If the gas pressure is too low, than you might experience the flame being too small. Check with the utility company about this problem. Also, pilot light tube, its orifice might be clogged with the dirt found in the gas line. Some elements you can clean, but if there is dirt in 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.
Important: Before troubleshooting 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. Make sure that the tank is completely filled with water before lighting the pilot light.