Exhaust Collector Limit Switch Open
Check to see if the exhaust collector high limit switch, located in the exhaust collector area near the pressure switch has opened. Depress the red manual reset button on the high limit switch. If it resets with a “click”, the switch has opened. Check for evidence of high temperatures in this compartment. If there is vidence of high temperatures, call Tech Support. Do not continue to operate the water heater if high temperature is occurring in this area.