66 Troubleshooting
Testing method
Fault
Possible causes
Testing method
Flame loss and noise
occurs after ignition
Low gas supply pressure
1. Check the gas supply pressure.
●
NG: 17-25 mbar, LP: 25-35 mbar
●
LP pressure drop occurs frequently during winter.
2. When static pressure is normal, the use of other gas appliances may cause
the boiler’s gas pressure to drop. Check the dynamic pressure.
Check the static pressure: Gas supply pressure in standby mode.
Check the dynamic pressure: Gas supply pressure at maximum combustion.
3. Check the gas pipe connections.
●
If a CSST connector has been used, ensure that it has not been
overtightened. An overtight connection can deform the seal and
obstruct the flow of gas.
4. Check the gas meter rating.
Flame loss and noise
occurs after ignition
PCB DIP switch setting
error
Check the PCB DIP switch settings.
1 2
O
N
Switch
Function
Setting
1 & 2
Fuel selection
LNG(G20)
1-OFF, 2-OFF
Not Used
1-OFF, 2-ON
LPG(G30)
1-ON, 2-OFF
LPG(G31)
1-ON, 2-ON
Flame loss during Stage 2
Blockage in the gas
orifice plate.
Flame loss will occur if the gas orifices in the dual venturi are clogged.
●
Remove the gas inlet pipe and check for debris inside the dual venturi.
Remove and clean the orifice plate if necessary.
Other faults
PCB DIP switch setting
errors
Check the PCB DIP switch settings.
* Check the correct resistance for flame detection AD.
PCB fault
If the error conditions continue after checking these items, replace the PCB.
Summary of Contents for NCB300-28K
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