90 Troubleshooting
5.2.22 Error 740
Error conditions and Check Items
Error
Description
E740
Abnormal outdoor sensor
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.
Check items
1. Check the parameter setting.
2. Check the outdoor sensor.
Is the Outdoor sensor
installed properly?
Is the outdoor thermistor
normal?
Check connecter
Change the Outdoor Reset Control
mode setting.
Replace the outdoor thermistor.
No
No
Yes
Yes
5.2.23 Error 782
Error occurrence conditions and check items
Is the wiring from the front panel
properly connected to the PCB?
Reconnect panel to the PCB
Step 1: Reset the unit.
Step 2: If problem persists, replace
the PCB and front panel.
Yes
NO
Содержание NCB500-2S/37K
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