Version 2.21
84 NPE Service Manual
Check method
Fault
Possible
Causes
Check method
Flame loss and noise
occurs after ignition
Low gas
supply
pressure
1. Check the gas supply pressure.
●
NG: 3.5” - 10.5” W.C, LP: 8” - 13” W.C
●
LP pressure drop occurs frequently in the winter.
2. 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.
Check the static pressure: Gas supply pressure during stand by.
Check the dynamic pressure: Gas supply pressure at (2nd stage MAX combustion setting:
DIP S/W 1-1 ON) MAX combustion
3. Check the gas pipe connector.
●
If a CSST connector has been used, check to ensure that it is not been overtightened
resulting in the seal obstructing gas flow.
4. Check the gas meter capacity (Example)
●
Gas meter Water heater Furnace Domestic gas stove
425 CFH (Gas Meter) ≥ 195 CFH (Water 58.8 CFH (Furnace)
+ 63.7 CFH (Domestic gas stove)
1 CFH = 1,020 Btuh
5. If too much pressure is exerted on the nut component while installing the gas pipe may
reduce the gas supply due to packing push-out and Teflon blockage, etc.
