The pilot light safety device associated with gas appliances such as furnaces and water heaters depends on a self-generated electric current and a complete electrical circuit. The current is generated via a piezoelectric cell. When a piezoelectric cell is heated, it generates a current. The heat comes from the pilot light flame which is in close proximity to the piezoelectric cell. This current activates the safety controller to allow the gas to continue to flow. When this current stops flowing, the safety controller shuts off the gas. The design of the circuit is to shut the gas off if the pilot light flame goes out. In my experience, the main failure of this circuit is not the piezoelectric cell or the safety controller. It is the connection at the safety controller where the piezoelectric aluminum tubing screws in. At that point, the aluminum tubing screws into either an aluminum or copper socket completing an electrical circuit.

As many of you may be aware, aluminum to aluminum or aluminum to copper electrical connections are fraught with problems. When aluminum is exposed to the oxygen in air, it creates aluminum oxide. Over time, this oxide builds up, creating more and more electrical resistance. In the past, when aluminum was first used in house and RV wiring, this build up of resistance due to higher current flow caused many devastating fires. Changes were made to electrical codes to prevent the formation and build up of oxides where aluminum wiring or connections were made. Usually this involved the use of dielectric grease to stop oxygen from reaching the connection. For some reason, all the appliances I have serviced, even newer ones, do not use dielectric grease in the pilot light safety circuit. There is not enough current generated by the piezoelectric cell to start a fire, but what occurs is that the build up of resistence reduces the current flow enough to cause the safety controller to shut the gas off just as if the pilot light flame went out.

There is an easy way to correct this problem. Shut off the gas and the electricity to the appliance. Unscrew the piezoelectric tube from the safety controller. Use a plastic scrub pad to rather gently remove the oxide from both sides of the connection, both the external tube connector threads and the internal safety controller threads. Blow any residue away. Coat the threads with dielectric grease and reconnect the fittings. Turn the power and gas back on and relight the appliance as directed on the safety controller. Do not be concerned about disconnecting the piezoelectric connection, there is no gas flowing through this tubing, it is strictly an electrical circuit that is not in any way connected to an external electrical circuit. Current is only present when the pilot light flame heats the piezoelectric cell and the circuit is complete. If you have shut off the gas, there is no pilot light flame, thus no current. The only caution is not to cross thread the fitting when reconnecting. Start the fitting by hand and use a proper wrench when removing and reconnecting, not a pair of pliers which may destroy the fitting.

I have done this maintenance procedure to both my own and my parents’ appliances for many years. I have a furnace and a water heater in one home that are thirty five years old and I have never had to replace a piezoelectric cell or a safety controller and they are both still working. In fact, I have never had to replace either in any appliance I have owned or serviced! If you are qualified, you can use an additional pilot light, piezoelectric cell, safety controller, and or custom circuitry to generate a current for other purposes when there is no other electricity available or during power outages.

Some appliance service personnel know only what they have been taught or know how to make more money. It takes the same amount of time to do either. But to replace the part, they make more money.