30
ADJUSTING AIR AND GAS FLOW RATES
Gas Filter
The gas filters remove the dust particles that are present in the gas, and prevent the elements at risk (e.g.: burners, counters and regu-
lators) from becoming rapidly blocked. The filter is normally installed upstream from all the control and on-off devices.
Adjusting the pilot gas flow rate
(RX515-RX520)
To change the pilot gas valve flow rate, proceed as follows:
1
remove the protection on the bottom of the valve, moving it counterclockwise (see next picture);
2
rotate clockwise the nut 1 as shown in to close the valve or counterclockwise to open.
To perform a finest adjustment, act directly on the pressure stabiliser as follows (see next picture):
3
remove the cap
T
: to increase the gas pressure at the outlet use a screwdriver on the screw
TR
as shown below. Screw to increase
the pressure, unscrew to decrease; once the regulation is performed, replace cap
T
.
Fig. 27
Keys
1
Gas filter
3
Gas proving system
4
Gas valves
5
Air pressure switch
6
Adjusting cam
7
Actuator
VPS504 Gas proving system
The VPS504 check the operation of the seal of the gas shut
off valves. This check is carried out as soon as the boiler
thermostat
TAB
gives a start signal to the burner, creating,
by means of the diaphragm pump inside it, a pressure in the
test space of 20 mbar higher than the supply pressure.
When wishing to monitor the test, install a pressure gauge
into the pressure supply point
PA
.
If the test cycle is satisfactory, after a few seconds the con-
sent light
LC
(yellow) comes on. Otherwise, the lockout light
LB
(red) comes on.
To restart, it is necessary to reset the appliance by pressing
the pushbutton
LB
.
4
6
5
7
1
3
LC
LB
PA
1
T
TR
Brahma gas valve EGR*12
Pressure stabiliser
