PART III: OPERATION
25
8
To adjust the
air flow rate in the high flame stage
, loose the
RA
nut and screw
VRA
as to get the desired air flow rate: moving
the rod
TR
towards the air damper shaft, the air damper opens and consequently the air flow rate increases, moving it far from the
shaft the air damper closes and the air flow rate decreases.
Note:
once the procedure is perfomed, be sure that the blocking nut
RA
is fasten. Do not change the position of the air damper
rods.
9
If necessary, adjust the combustion head position (see the dedicated paragraph)..
10 The air and gas rate are now adjusted at the maximum power stage, go on with the point to point adjustement on the
SV1
(gas
side) adjusting cam as to reach the minimum output point.
11 as for the point-to-point regulation, move the gas low flame microswitch a little lower than the maximum position (90°);
12 set the
TAB
thermostat to the minimum in order that the actuator moves progressively towards the low flame position;
13 move the gas low flame microswitch to the minimum to move the actuator towards the low flame until the two bearings find the
adjusting screw that refers to the lower position: screw
V1
to increase the rate, unscrew to decrease.
14 Move again the gas low flame microswitch towards the minimum to meet the next screw on the adjusting cam and repeat the pre-
vious step; go on this way as to reach the desired low flame point.
15 Now adjust the pressure switches.
Attention! if it is necessary to change the head position, repeat the air and gas adjustments described above.
VR
T
Siemens VGD..
VRA
RA
TR
SC
SV1
V1
Gas throttle valve open
Gas throttle valve closed
