Firing - Cuenod NC4 Instrucciones De Montaje, Servicio

Start Up
Cycle test

Firing

Safety unit settings and checks
Cycle test
· Open and immediately reclose the
shut-off valve.
· Switch the burner on.
· Close the regulation circuit.
· Unlock the control and safety unit
and check that it is working
correctly.
The program sequence should be as
follows:
controlled preventilation time
–
20 sec. (total preventilation time can
exceed 20 sec.),
electrode ignition 3 seconds,
–
the valves open,
–
the valves close no more than
–
3 seconds after opening,
burner stops due to either lack of
–
gas pressure or control and safety
unit lockout due to flame
disappearance.
If unsure, repeat above test.
Firing is only possible after this
essential test of the ignition cycle has
been carried out.
Burner head gas pressure
Burner
G20 G25
power
(kW)
119 pBr
(daPa)
15 11
NC4 25 24
35 37
40 47
NC6
50 63
50
60
NC9 70 64
85
97
48
Firing
Warning:
The unit may be fired when all the
requirements listed in the previous
sections have been met.
· Connect a microammeter scale
0-100µA DC in place of the
ionization bridge B1 (check polarity).
· Open the shut-off valve.
· Close the thermostat circuit.
· Unlock the control and safety unit.
The burner will operate.
· Perform a combustion test (CO - CO
as soon as the flame appears.
· Check the ionization current (value
between 8 and 20µA).
· Measure and compare (table):
– gas flow at the meter,
– gas pressure at point pBr and at
point 119 upstream,
– air pressure at point pL.
· If necessary, adjust:
– gas pressure using screw D for
NC4/6 and screw PG for NC9
– air pressure using setting knob
103B
– dimension Y with screw 15.
· Check combustion parameters.
The manufacturer's recommandations
concerning: flue gas temperatures
(boiler) and CO
followed in order to obtain the required
level of performance.
· With the burner working, and using
a foam designed for this purpose,
check for leaks in the valve
assembly connections.
No leaks should be observed.
Should analysis of the combustion tests
reveal that the CO value is too high,
modify it using the following diagrams:
1 Standard, 2 Modified
· Fit the two crosspieces C (stored on
the plate) between turbulator A and
diffusor D.
Air flap
G31
position
103 B
0 to 18
(daPa)
6 3,5
15 8
27 12
40 13
45 18
66 9
84 11
120 18
01/2005 - Art. Nr. 13 010 553B
),
2
(burner) should be
2
Burner head Dimension
air pressure
Y
pL
(mm)
(daPa)
8 17
18 20
22 25
27 25
29 30
35 25
36 30
52 35
Safety unit settings and checks
Gas pressure switch.
· Remove the cover to gain access to
the adjust screw.
· Connect a pressure gauge to
pressure take-off 119 upstream.
· Read the actual supply pressure.
· Switch the burner on.
· Slowly close the shut-off valve.
Once the theoretical minimum pressure
(see table) is reached:
· Determine the cut-off point by
turning screw E clockwise (+).
The burner should stop due to
insufficient gas pressure.
· Turn the screw anticlockwise (–) one
turn (corresponds to 15 to 25daPa).
· Check the setting by repeating the
test. Pressure switch is set.
m
Air pressure switch
· Remove the terminal cover.
· Connect a pressure gauge to the +
pressure take-off.
· Reopen the shut-off valve.
When the burner has been refired,
slowly turn screw V clockwise (+).
Determine and measure the cut-off
point (safety lockout).
· Turner screw V anticlockwise (–)
one turn to set the required value
(differential 10-20daPa).
· Restart the burner.
· Gradually close off the burner air
intake.
· Check that the CO value remains
below 1000ppm prior to safety
lockout.
If not, increase the air pressure switch
setting and restart the test.
· Disconnect the gas measurement
instruments.
· Reclose the pressure take-offs.
· Restart the burner.
· Check for leaks downstream from
the valve assembly and between
flange and burner front.
· Simultaneously disconnect both
microammeter cables.
The burner should immediately lock out
to safety.
· Put the ionization bridge back in its
place.
· Put the covers back in their places.
· Restart the burner.
· Check the combustion parameters
under actual service conditions
(doors closed, etc.) and test the
various connections for gas leaks.
· Record the results in the relevant
documents.
· Set the burner to automatic mode.
· Convey the information required for
operation to those concerned.