High Temperature Limit Switch - Navien NCB300-28K Service Manual

4.7.2 High Temperature Limit Switch

Item
Function
Fault
Symptoms
Error codes
Diagnostics
Testing/inspection
information
38 System Details
1. Overheat prevention switch.
2. If the switch detects extremely high temperature, the boiler will automatically trip and shut down.
3. Excessive high water temperatures (> 105°C) in the heat exchanger will activate the high limit switch.
Unable to detect high water temperature conditions if the switch malfunctions.
Unable to shut down the boiler if the water temperature from the heat exchanger exceeds 105°C.
E016, E046
1. Visual inspection: Check wire connections are secure and inspect for wire damage.
2. Resistance test: Confirm that the resistance is within the specification shown below.
Resistance range: < 1.0Ω
Description