Navien NCB500-2S/37K Service Manual page 114

VERIFY FLUE INTEGRITY
Analyser readings indicate that combustion products and inlet air
Is
O > 20.6%
2
and
CO < 0.2%
2
TURN OFF APPLIANCE AND CALL
ATAG TECHNICAL HELPLINE FOR
ADVICE. 0800 254 5065
THE APPLIANCE MUST NOT BE
COMMISSIONED UNTIL PROBLEMS ARE
IDENTIFIED AND RESOLVED.
Check all seals around the appliance burner,
Rectify where necessary.
Is
CO less than
350ppm and
CO/CO
2
than 0.0040
TURN OFF APPLIANCE AND CALL
MANUFACTURER'S TECHNICAL HELPLINE
FOR ADVICE.
THE APPLIANCE MUST NOT BE
COMMISSIONED UNTIL PROBLEMS ARE
IDENTIFIED AND RESOLVED. IF
COMMISSIONING CANNOT BE FULLY
COMPLETED, THE APPLIANCE MUST BE
DISCONNECTED FROM THE GAS SUPPLY IN
ACCORDANCE WITH THE GS(I&U)R.
NOTE: Check and record CO and combustion
ratio at both max. and min. rate before contacting
the manufacturer.
YES
NO
YES
ratio less
NO
From
previous
page
O > 20.6%
2
NO
and
CO
2
CHECK CO AND COMBUSTION RATIO AT MAX. RATE
With boiler still set at maximum gas rate, insert analyser probe into
Allow readings to stabilise before recording.
CO less than
350ppm and
NO
CO/CO
2
than 0.0040
SET BOILER TO MINIMUM RATE
In accordance with boiler instructions, set boiler to operate at
combustion to stabilise.
CHECK CO AND COMBUSTION RATIO AT MINIMUM RATE
gas sampling point. Allow readings to stabilise before recording.
CO less than
350ppm and
NO
CO/CO
2
than 0.0040
BOILER IS OPERATING SATISFACTORILY
No further actions required.
other commissioning procedures are completed.
Complete Benchmark Checklist, recording CO and combustion ratio
readings as required.
Is
< 0.2%
YES
< = less than or
equal to
> = greater than or
equal to
Is
ratio less
YES
Is
ratio less
YES
Inspection and Maintenance Schedule 113