High Limit Switch - Navien NPE-180A Service Manual

4.11.2 High Limit Switch

Check Point
1. Overheat prevention switch.
2. If the unit detects extremely high temperatures, it will automatically trip and shut down the unit.
Function
3. Excessively high water temperatures (more than 197.6 °F or 92 °C) in heat exchanger will activate the high
limit switch.
Failure Event Unable to detect excessively high water temperature if switch fails.
Effects Unable to shut down the water heater if the water temperature from the heat exchanger exceeds 197.6°F (92°C).
Error Code E016, E046
1. Visual inspection: Connection and/or breakage of wires.
Diagnostic
2. Resistance check: Check range of resistance shown below.
Color/Number
Resistance range : under 1.0 Ω
of wires
Check Point
System Details 59