I have an AO Smith hot water heater that won't stay lit. The electric element heats up and glows red, then the gas ignites. It stays ignited for about 3 seconds, then shuts off again. This cycle repeats itself about 5 times, then it gives up.
This is a closed system, at least that's what I call it. There is an electric vent system that clicks on for the exhaust gas. Someone told me it could be the high temperature air switch. I wasn't sure if it could be a thermocouple, much like you have on a gas furnace.
Any thoughts would be appreciated.
Regards,
Matt