Navien NCB-700-2S+/42K Service Manual page 84

Testing method
Fault
Dual venturi action error
Possible causes
1. Disconnect all cables from the dual venturi.
Defective dual venturi
cable or harness
2. Use a multi-meter to test the dual venturi's electrical wiring.
1. Turn off the power to the boiler at the main power switch (not the front
2. Turn on the power.
3. Wait until Fan Auto Adjusting is complete.
4. Enter the dual venturi test mode and perform a test.
Dual venturi not
operating
5. If error message E060 is displayed, replace the dual venturi.
6. If a dual venturi error does not occur, replace the APS.
Testing method
panel power button) and wait for 10 sec.
1) Repeat the test at least twice. Turning the unit ON and OFF once is one
test cycle. ON → OFF → ON → OFF → ...... is the minimum sequence.
2) Confirm that the dual venturi is operating correctly.
a. Listen to the dual venturi while it is running and check for
operational noise (an audible click is heard at boiler ON and boiler
OFF).
b. If operational noise cannot be heard because of ambient noise,
disassemble the dual venturi and perform a visual inspection.
Troubleshooting 83