©Navien America Inc. 2010 NR/NP series service Manual
89
Version 2.0
Check method
Check methodCauseError type
Flame blowout
and noise
occurs after
ignition
Flame blowout
and noise
occurs after
ignition
Low gas supply
pressure
PCB capacity
setting error
Dierential
gas pressure
adjustment error
1. Check the gas supply pressur e.
NG: 5”(6” 180 MODEL) ~10.5” W.C, LP: 8”(9” 180 MODEL)~13.5” W.C
LP pressure drop occurs frequently in the winter.
2. Check the exible pipe diamet er.(3/4”)
3. While the static pressure is normal, a large dierence of dynamic
pressure may cause drop of gas pressur e. Therefore, it
is requir ed to
check the dynamic pressure.
ȄCheck the static pressure: Gas supply pressure as the boiler is stopped.
Check the dynamic pressur e: Gas supply pressur e at boiler MAX
combustion
4. Check t
he gas pipe connector.
Excessiv e force in fast ening nuts at installation of gas pipe may move
the packing and block the Teon sealing, causing a drop of gas
supply pressure.
5. Check the meter class (Example)
Gas met er Water heater Furnace Domestic gas
stove
425 CFH ≥ 195 CFH + 58.8 CFH + 63.7 CFH
* 1 CFH = 1,020 Btuh
3-stage MIN dierential gas adjustment error.
Turn the adjusting screw under the main gas valve. ½ turn, and check
the combustion.
Adjust dierential pr essur e with the meter after ignition.
PCB DIP S/W 2,3 ON / Stage 3 MIN main gas valve.
Check the PCB DIP S/W capacity setting.
Capacity
(Btu/h)
DIP Switch
Model
NR-180(A)/NP-180(A)
NR-210(A)/NP-210(A)
NR-240(A)/NP-240(A)
150,000
180,000
199,000
5
OFF
ON
OFF
6
OFF
OFF
ON
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