Version 1.4
98 NCB-E Service Manual
Check method
Fault
Possible Causes
Check method
Flame loss and noise
occurs after ignition
Low gas supply pressure
1. Check if a gas valve is opened or not.
2. Check the gas supply pressure.
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NG: 3.5” - 10.5” W.C, LP: 8” - 13.5” W.C
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LP pressure drop occurs frequently in the winter.
3. While the static pressure is normal, the use of another gas appliance may cause
a possible drop in gas pressure to the unit. Therefore, it is required to check the
dynamic pressure.
4. Check the static pressure at stand by.
Check the dynamic pressure at MAX combustion (2nd stage MAX combustion
setting: DIP S / W 1-1 ON).
5. Check the gas pipe connector.
●
If a CSST connector has been used, check to ensure that it is not been over
tightened resulting in the seal obstructing gas flow.
6. Check the gas meter capacity (Example)
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Gas meter Boiler Furnace Domestic gas stove
425 CFH (Gas Meter) ≥
195 CFH ( 58.8 CFH (Furnace)
+ 63.7 CFH (Domestic gas stove)
CFH = 1,020 Btuh
Tightness of Screw or
Ground Bolt
Check the tightness of the screw or ground bolt in the C SC heat
exchanger.
●
Cause: Screw or ground bolt in the chamber and SC heat exchanger can be
loosened by the vibration or external impact when operating the boiler (water
heater).
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Check-up: A failure in the current flow between the chamber and burner may
cause the flame-out; therefore, the tightness (fastened) of the screw needs to be
checked. [Fasten the ground screw (2EA) after fastening the assembly screw (3EA)
in the front of the heat exchanger]