PART III: OPERATION
29
ADJUSTING AIR AND GAS FLOW RATES
Adjustments - brief description
Adjust the air and gas flow rates at the maximum output (“high flame”) first, by means of the air damper and the adjusting cam respec-
tively.
Check that the combustion parameters are in the suggested limits.
.Check the flow rate measuring it on the counter or, if it was not possible, verifying the combustion head pressure by means of a
differential pressure gauge.
Then, adjust the combustion values corresponding to the points between maximum and minimum: set the shape of the adjusting
cam foil. The adjusting cam sets the air/gas ratio in those points, regulating the opening-closing of the throttle gas valve.
Set, now, the low flame output, acting on the low flame microswitch of the actuator in order to avoid the low flame output increasing
too much or that the flues temperature gets too low to cause condensation in the chimney.
Fuel
Adjusting procedure
1
Turn the burner on by means of its main switch
A
: if the burner locks (LED
B
on in the control
panel) press the RESET button (
C
) on the control panel. See chapter “Operation” for further
details.
2
check the fan motor rotation;
3
Start the burner up by means of the thermostat series and wait unitl the pre-purge phase comes to end and that burner starts up;
4
the burner starts up in the low flame stage: drive the burner to high flame stage, by means of the “high/low flame” thermostat
TAB
.
5
adjust the burner combustion values in the high flame stage as described in the following steps.
6
go on adjusting air and gas flow rates: check, continuosly, the flue gas analisys, as to avoid combustion with little air; dose the air
according to the gas flow rate change following the steps quoted below;
7
acting on the pressure governor of the valves group, adjust the
gas flow rate in the high flame stage
as to meet the values
requested by the boiler/utilisation:
-
Multibloc MB-DLE:
the valve is adjusted by means of the
RP
regulator after slackening the locking screw
VB
by a number of
turns. By unscrewing the regulator
RP
the valve opens, screwing the valve closes. The pressure stabilizer is adjusted by operating
the screw
VS
located under the cover
C
. By screwing down the pressure is increased and by unscrewing it is reduced.
Note:
the
screw
VSB
must be removed only in case of replacemente of the coil.
- Siemens VGD valves group:
remove cap
T
and act on the
VR
adjusting screw to increase or decrease the pressure and conse-
quently the gas rate; screwind
VR
the rate increases, unscrewing it decreases (see next figure).
WARNING! During commissioning operations, do not let the burner operate with insufficient air flow (danger of
formation of carbon monoxide); if this should happen, make the fuel decrease slowly until the normal combustion
values are achieved.
WARNING! the combustion air excess must be adjusted according to the values in the following chart.
Recommended combustion parameters
Fuel
Recommended (%) CO
2
Recommended (%) O
2
Natural gas
9 ÷ 10
3 ÷ 4.8
LPG
11 ÷ 12
2.8 ÷ 4.3
DANGER! The burner must be used only with the fuel specified in the burner data
plate.
Type --
Model
--
Year --
S.Number --
Output --
Oil Flow
--
Fuel
--
Category --
Gas Pressure
--
Viscosity --
El.Supply --
El.Consump. --