Navien NCB300-28K Installation & Operation Manual page 63

Inspecting the Ignition and Flame Detector Electrodes
1. Remove the ignition and flame detector electrodes from the
boiler heat exchanger.
2. Remove any deposits accumulated on the ignition/flame
detector electrode. If the electrodes cannot be cleaned
satisfactorily, replace with new ones.
3. Replace ignition/flame detector electrode, making sure
gasket is in good condition and correctly positioned.
Checking the Ignition Ground Wiring
1. Check that the ground wire is in good condition and
securely attached to the boiler casing.
2. Check ground continuity of wiring using continuity meter.
3. Replace ground wires if ground continuity is not satisfactory.
Checking all Boiler Wiring
Inspect all boiler wiring, making sure wires are in good condition
and securely attached.
Checking the Control Settings
Check settings of external limit controls (if any) and adjust if
necessary.
Performing Start-up and Checks
1. Start boiler and make sure that the boiler is operating
properly.
2. Verify cold fill pressure is correct and that operating pressure
does not go too high.
Check the Burner Flame
1. Inspect flame through observation window.
2. If the flame is unsatisfactory at either high fire or low fire,
check for obstructions in the flue.
62 Maintaining the Boiler
Checking the CO₂
1. Check the CO₂ readings at full load and low load.
2. Check the CO readings and combustion performance
(CO/CO₂ ratio).
3. Check the CO readings and combustion performance.
For more information, refer to the 15th step in "12.1 Gas
Conversion" on page 68. The combustion reading (CO/CO₂
ratio) must be less than 0.004.
4. If the combustion reading (CO/CO₂ ratio) is greater than
this, and the integrity of the complete flue system and
combustion circuit seals has been verified, and the inlet gas
pressure and gas rate are satisfactory either:
Perform the full service. For more information, refer to
●
"11.5.2 Full Service" on page 62.
Set the Gas Valve. For more information, refer to "5.3
●
Measuring the Inlet Gas Pressure" on page 32.
Review with the Owner
1. Review the User's Information Manual with the owner.
2. Emphasize the need to perform the maintenance schedule.
3. Remind the owner of the need to call a licensed contractor
should the boiler or system exhibit any unusual behaviour.
4. Remind the owner to follow the proper shutdown procedure
and to schedule an annual start-up at the beginning of the
next heating season.
5. After servicing, complete the relevant Service Interval
Record section of the Benchmark Checklist located on the
inside back page of this document.
11.5.2 Full Service
For reasons of safety and economy, it is recommended that the
boiler is serviced annually. Servicing must be performed by a
competent person in accordance with BS 7967-4. After servicing,
complete the relevant Service Interval Record section of the
Benchmark Checklist located on the inside back page of this
document.
Where a full service is required, refer to "11.5.1 Interim
Note
Service" on page 60.