Q. My hot-water tank in LP-gas mode will ignite, make a clicking noise, then shut off. I called the dealer and talked to a salesperson. He asked me if I ran the tank with electricity more than with gas. I told him yes. He said that I should run the tank with gas on a regular basis, because using electricity so often made the sensor go bad.
Is there anything to this? Can I change the sensor myself, and where would this be located?
— C.G., Opelousas, Louisiana
A. The sensor your mechanic refers to is the thermistor, C.G., and it’s located in the metal bracket that also holds the pilot light and the main burner. I’m not sure how the mechanic figures more use of the gas heat will make the thermistor last longer, but it’s easy to replace.
Look for a small cylindrical unit with a wire leading from it over to the heater’s circuit board. Some thermistors are held in place with a simple press clip, and others have a screw-on retainer. Remove the old one, replace it with a new one and reinstall the wire. The tip of the thermistor must be in the pilot-light flame or it won’t function.
While you’re doing some water-heater R&R, have a technician check for adequate LP-gas pressure. It should be around 11 inches WC, although from your description it sounds like the thermistor, rather than the LP-gas pressure, is the likely culprit for your operating problems.
Jeff Johnston, TL consulting editor, started RVing at age 6. During his more than 20 years as a writer/photographer, he has worked for Truckin’ and Four Wheeler magazines before joining TL’s technical staff in 1985. Johnston also has produced an award-winning travel video and TV commercials