Cuenod NC12 GX107/8, Operating Instructions Manual

10/2007 - Art. Nr. 13 017 700B

17

Start-up

Checking the operating sequence
1-stage burner firing
Setting and checking of safety devices

Checking the operating sequence

•  Open the fuel hand-operated 1/4 turn 

valve and close it again immediately.

•  Switch the burner on.
•  Close the thermostatic circuit.
•  Unlock the control and safety unit and 

check to see that it functions properly.

The programme must proceed as 
follows:
-  preventilation: 20s,
-  electrode firing: 3s,
-  opening of the valves,
-  closing of the valves,

within no more than 3s after their 
opening,

-  Burner shutdown due to a lack of gas 

pressure or locking of the control and 
safety unit due to flame extinguishing.

If a doubt arises, repeat the above 
test.

The firing can take place only after the 
operating sequence has been checked 
(this operation is of prime importance).

1-stage burner

Warning:
The firing can take place when all 
the conditions listed above are 
fulfilled, especially the field pre-
setting of the fuel valve.

•  Connect a microammeter (scale 0 to 

50µA DC) in place of the ionisation 
bridge.

•  Mount pressure gauges upstream and 

downstream of the valve.

•  Open the fuel valves.
•  Close the thermostatic circuit.
•  Unlock the control and safety unit.
The burner is in service.
•  Check the combustion (CO and CO

2

index) as soon as the flame is 
apparent.

•  Read the ionisation current value 

(ranging from 15 to 25µA).

•  Measure the gas flow rate on the 

meter.

•  Adjust the gas flow rate by acting upon 

the pressure controller.

•  Adjust the air flow rate by acting upon 

hand control 

103B

.

•  Make it rotate toward 

+

: 

the CO

2

 index decreases and vice 

versa.

•  Optimize the firing quality and the 

combustion results by acting upon
 - The setting of valve MB DLE instant

flow rate.

•  Make plug key 

B

 rotate in a cw 

direction toward 

arrow -

: 

the flow rate decreases and vice versa 
and the firing is more flexible.
 - The setting of secondary air at

dimension 

Y

.

•  Make plug 

A

 rotate in a cw direction 

toward 

arrow -

: 

the CO

2

 index decreases and vice 

versa. Modifying dimension 

Y

 may 

involve the adjustment of the air flow 
rate.

•  Check the combustion.
Comply with the smoke temperature 
value recommended by the boiler 
manufacturer to obtain the required 
effective output.
•  Tighten the valve locking screw.
•  Stop the burner and restart it. 
Assess its operation.
•  Check the tightness of the gas 

manifold connections with the burner 
in service by using a suitable foaming 
agent.

No leakage must be detected.

•  Check the safety devices.

Setting and checking of safety 
devices

Gas pressure switch
•  Set it to the minimum distribution 

pressure. 

The burner is in service.
•  Slowly close the fuel hand-operated

1/4 turn valve.

The burner must cease to function due 
to a lack of gas pressure.
•  Open the hand-operated 1/4 turn valve 

again. 

The burner restarts automatically. 
The pressure switch is set.
•  Fix, screw the cover.

Air pressure switch
The burner is in service at firing flow 
stage.
•  Detect the air pressure switch 

switching off point (locking).

•  Multiply the value read by 0.9 to obtain 

the setting point.

•  Restart the burner.
•  Gradually plug the burner air inlet.
•  Check to see that the CO index 

remains below 10,000ppm before 
locking the unit. 

Otherwise, increase the setting value of 
the air pressure switch and repeat the 
test.
•  Disconnect the gas measuring 

instruments.

•  Close the pressure taps.
•  Unlock the unit.
The burner is in service.
•  Check the tightness.
•  Disconnect the two wires on the 

microammeter simultaneously. 

The unit must be locked immediately.
•  Replace the ionisation bridge.
•  Replace the covers.
•  Unlock the unit. 
The burner is in service.
•  Check the tightness between the 

flange and the boiler front wall.

•  Check the combustion under 

operating conditions (doors closed, 
etc.) and the circuit tightness.

•  Record the results on the relevant 

documents and give them to the 
agent.

•  Switch the burner to AUTO.
•  Provide all the data required for proper 

operation.

•  Affix the boiler house plate so that it be 

apparent.

