Navien NHB-055, Service Manual

Page: 109 / 147

NHB Service Manual 109 Version 1.0
5.2.13 218Error
Error conditions and Check Items
Error Description
E218
Heat exchanger input temperature
sensor open
If an error (open: MΩ) in the heat exchanger input temperature sensor is detected, the system
displays the 218E error on the front panel. If this occurs, the boiler initiates shutdown.
Check items
1. Check if the heat exchanger input temperature sensor connector is wet due to any reason,
including leakage.
2. Replace the defected heat exchanger input temperature sensor.
3. Replace the controller.
Is the inlet thermistor
normal?
Check connector
(#3 and #4 of CN 13)
Replace inlet thermistor
Resistance between #3 and #4 of CN13
is from 0.437kΩ to 176kΩ at normal
condition. (see page 63-64 for Wiring
Diagram)
No
Yes
Before measuring resistance of the
thermistor, detach the connector
from the PCB.