B
LB 429
Blu 170 ÷ 350 P /P AB
pag.18
ADJUSTMENT OF GAS MINIMUM PRESSURE SWITCH
- Unscrew off and remove cover M. - Set regulator N to a value equal to 60% of gas nominal feed
pressure (i.e. for nat. gas nom. pressure = 20 mbar, set regulator to a value of 12 mbar; for L.P.G. nom.
pressure of G30/G31- 30/37 mbar, set regulator to a value of 18 mbar).
Screw up cover M
ADJUSTMENT OF THE AIR PRESSURE SWITCH
Unscrew screws A and B and remove cover C.- Set the pressure switch to the minimum by turning
regulator D to position 1. - Start the burner and keep in low flame running, while checking that com-
bustion is correct. Through a small cardboard, progressively obstruct the air intake until to obtain a
CO2 increase of 0,5÷0,8% or else, if a pressure gauge is available, connected to pressure port E, until
reaching a pressure drop of 1 mbar (10 mm of W.G.). - Slowly increase the adjustment value of the air
pressure switch until to have the burner lockout. Remove the obstruction from the air intake, screw on
the cover C and start the burner by pressing the control box rearm button.
Note: The pressure measured at pressure port E must be within the limits of the pressure switch
working range. If not, loose the locking nut of screw F and gradually turn the same: clockwise to
reduce the pressure; counterclockwise to increase. At the end tighten the locking nut.
Rated pressure : G 20 = 20 mba - G 25 = 25 mbar - G 30 = 29 mbar - G 31 = 37 mbar
2,5
5
10
15
50
25
35
30
40
45
20
0,4
0,6
0,9
3,0
1,5
2,1
1,8
2,4
2,7
1,2
I
L
M
N
A
B
C
D
E
F
G
H
WORKING OF THE BURNER WITH THE LEAKAGE CONTROL DEVICE
VPS 504 (OPTIONAL)
When the thermostats are closed, the gas leakage control device checks the valve seals by pressurizing the circuit between the two
gas valves. When test pressure is reached the device remains in stand-by for about 25 seconds.
At the end of the test the yellow pilot light on the control device lights up and the burner is enabled to carry out the start-up cycle.
If the seal on one of the valves is faulty and this causes a drop in test pressure, the device puts the system into the safety condition
and the red pilot right on the device lights up. The flame control device starts the burner fan to carry out prewashing of the com-
bustion chamber,checking fan air pressure via the air pressure switch. After preventilation the ignition transformer starts operating,
generating a spark between the electrodes and simultaneously the gas valves open (safety gas valve VS and first stage operating valve
VL). If the flame does not ignite or goes out, total safety is ensured by an ionization detection probe.
The safety time limit in the event of no flame is less than 2 seconds at start-up and less than 1 during operation.
In the event of no gas being supplied or of a considerable drop in pressure the minimum gas pressure switch interrupts burner ope-
ration. About 20/30 seconds after ignition the flame control device commands operation of the second stage via the gas valve and
air servocontrol, thus taking the burner to maximum power.
1
Pressure governor adjustment
2
Fast opening hydraulic brake’s adjustment
3
Flow rate adjustment (
Low flame flow rate
adjustment for AB version)
4
High flame flow rate adjustment
5
Inlet pressure port
6
Pressure governor membrane’s bleed
7
Minimum presure switch adjustment
(VPS 504)
8
Pressure port after gas filter
9
Pressure port after pressure governor. During leakage control test,
is used to measure test pressure (~150 mbar). When burner is
running, it is used to measure governor’s outlet pressure.
10
Working lamp (yellow)
11
Leakage control device rearm button (red)
With the burner switched off, connect a DC microammeter with a 0÷50 or 0÷100 µA dial. When the burner is running, and is
properly adjusted, the value read must be steady and never be smaller than 1,5/3 µA.
FLAME DETECTION SYSTEM CHECK
1
min. 1,5
µ
A
50
µ
A
SATRONIC
DLG 976 - DMG 972
LANDIS & STAEFA
1
LGB21-LGB22 min. 3
µ
A
LMG21-LMG22 min. 2
µ
A
