615Error - Navien NHB-055 Service Manual

5.2.24 615Error

Error occurrence conditions and check items
Error
E615 error
Check items
5.2.25 740Error
Error conditions and Check Items
Error
E740
Abnormal outdoor sensor
Check items
120 NHB Service Manual
Abnormal signal input by PCB.
1. Turn the POWER RESET switch OFF then ON (or unplug and replug the power supply.
2. If the system still displays E615, replace the main PCB.
If an error (under 2.2kΩ or over 122.2kΩ) in the outdoor sensor is detected continuously for
3 seconds, The system displays the error message E740 on the front panel. If this occurs, the
boiler changes the control mode from Reset Curve Mode to Normal Mode.
1. Check the parameter setting. (refer to page 49-51)
2. Check the outdoor sensor
Is the Outdoor sensor
installed properly?
Yes
Is the outdoor thermistor
normal?
Yes
Check connecter
(#1 and #2 of CN11)
Description
Description
No
Change the Outdoor Reset Control
Mode setting (refer to page 49-51).
No
Replace the outdoor thermistor.
Version 1.0