Sep 18 2012 · My boiler keeps hard locking out with a E3 code when the hot water heater calls for a large amount of hot water (i.e filling up tub) It also causes one of our circulating pumps Taco 009-F5 to get quite hot (that leads our second floor) and it starts making a weird grinding sound-- I trouble shooted by kicking on the in floor system and the pump works just fine for circulating the 2nd floor.
Error E03 - A safety thermostat of the protection (thrust sensor) / pressure switch - thrust sensor has occurred. Error E04 - Failure of frequent flame failure. Error E05 - Malfunction of the temperature sensor of the heating circuit. Error E06 - Malfunction of the hot water temperature sensor (NTC).