Use And Maintenance; Gas Valve - Sime RS Mk.II Serie Instrucciones Para El Instalador Y El Usuario

4

USE AND MAINTENANCE

4. 1

GAS VALVE

Boilers are normally produced with a
HONEYWELL V4085 gas valve (fig. 19).
NOTE:
The seal on the slow opening control
(accelerator 5) must not be tampered
with in any way or the valve guarantee
will be nullified.
4. 1 . 1 Rectified connector
The electrical command on valve V4085 is
supplied by a rectified connector (code
6243600), which must be replaced if it is
broken. Follow the instructions in fig. 20 to
replace it.
4.2 GAS VALVE ADJUSTMENT
"RS Mk.II" boilers have a gas valve with a
coil assembly which permits power to be
reduced by about 40% of the rated power
level before the burner goes out all the way
through a control thermostat with dual
contacts. SIME sets the maximum pressu-
re setting and the reduced pressure set-
ting on the production line, and these set-
tings should not be changed except in the
case of change to another type of gas
(butane or propane), in which case they
may be changed complying with the values
shown in Table 3.
This operation must be performed exclu-
sively by authorised service technicians,
or the guarantee will be nullified.
Operations involved in adjustment of pres-
sure settings must be carried out in a cer-
tain order, adjusting the maximum pressure
first and then the reduced pressure.
4.2. 1 Adjusting maximum
and minimum pressure
Proceed as follows to set the maximum
pressure (fig. 21):
– Connect the column or pressure gauge
to the pressure intake on the burner
manifold.
– Slacken screw (4) all the way.
– Set the thermostat knob to the maxi-
mum value.
– Turn on the power supply to the boiler.
– Slacken lock nut (1) and turn union (3):
turn the union anti-clockwise to reduce
pressure, or clockwise to increase it.
– Tighten lock nut (1).
– Turn on the main switch repeatedly,
checking that pressure corresponds to
the values specified in Table 3.
After setting maximum pressure, set mini-
mum pressure as follows (fig. 21):
– Once again, use the column or a pressu-
re gauge to read pressure.
– Turn off the power supply to the coil (2)
– Turn on the boiler and allow it to operate
KEY
1 Electrical control
2 Coil
3 Pressure intake
4 Connection flange
5 Slow opening control
(accelerator)
TABLE 3
Type of gas Reduced burner pressure
Methane - G20
Butane - G30
Propane - G31
KEY
1 Electrical control
2 Rectified connector
KEY
1 M13 lock nut
2 Coil
3 Maximum pressure control union
4 Reduced pressure
control screw
at rated power for a short time, then
slowly turn the thermostat knob down
until you hear the first thermostat con-
tact trip.
mbar
6
15
15
– Leave the thermostat knob in this posi-
tion and turn the screw (4) to find the
reduced pressure value specified in Table
3 for the type of gas in use; turn screw
(4) anti-clockwise to decrease pressure
or clockwise to increase pressure.
– Restore the power supply to the coil.
– Turn on the main switch repeatedly,
checking that pressure corresponds to
the specified value.
4.3 SECOND GAS
SOLENOID VALVE
The gas assembly is normally produced with
Fig. 21
a second gas solenoid valve which is nor-
mally closed.
4.4 COIL
Coil components are identified in fig. 22.
KEY
1 Conical spring
2 Spring anchor
3 M13 locknut
4 Max. pressure control union
5 Coil
6 Spring
7 Clips
8 Reduced pressure
control screw
Fig. 19
Max. burner pressure
mbar
9,7
28
35
Fig. 20
Fig. 22
65