On the covered Noritz tankless water heater, 20, EC20 means the high limit switch has been triggered. It trips if water in or leaving the heat exchanger approaches 176 to 205 degrees Fahrenheit. Combustion stops immediately and the unit closes the water control servo. First, unplug the unit, let it cool, then plug it back in once.
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0 of 2 completedWhat to do first
ReversibleUnplug the unit, let it cool, then plug it back in once.
Correct only the documented fault domain
ReversibleNoritz says this usually requires a hard reset by disconnecting power, and that the most common cause is scale in the heat exchanger. If you keep resetting without fixing the cause you are likely to reach EC14, which is not resettable. If the switch or its wiring is bad, the code usually will not reset even when the unit is cold. Noritz recommends a descale flush, plus a combustion cleaning if there is dust or lint.
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What does 20, EC20 mean on a Noritz tankless water heater?+
The high limit switch has been triggered. It trips if water in or leaving the heat exchanger approaches 176 to 205 degrees Fahrenheit. Combustion stops immediately and the unit closes the water control servo.