Supplied By www.heating spares.co Tel. 0161 620 6677
18
DOMINA PLUS F 24 - 30 E
FERELLA EXTRA F 24 - 30 MEL
Version - 09.2002
IN
OUT
COMMON
25±50V DC
80±110V DC
B
Gas valve
It supplies gas to the nozzles between a minimum and maximum pressure. For
the valve to work correctly, it is necessary for the pressure upstream from it to
be stable and suited to the type of gas being used, while the valve will supply a
regular pressure to the nozzles. The gas valve contains two operators. The
function of the first one is to open or close, while the task of the second one is
to modulate the capacity according to the system's requirements. The signal
comes from the card and is in the form of continuous voltage. The first operator
receives fixed voltage that may be between 80 and 110V DC, for the second
operator the voltage will vary between 25 and 54V DC according to the need of
the main card.
Checks
If the valve doesn't work:
·
The only possible check is to see whether gas comes out of the screw "B" at
the rated pressure when setting the boiler on "test" with the boiler at full power
(see "Test Functions" chap. 3.1).
Modulation
The control system governs its boiler capacity so as to keep the delivery temperature constant in accordance
with the settings on the control panel. The nozzle gas pressure is modulated by the valve and specifically via
the 2nd operator. The card provides a change in continuous voltage (between 25 and 54 V
DC
) according to the
difference between the delivery temperature and the set point.
Checks
Modulation can be checked in three ways:
·
Visually, by checking the flame.
·
Using a pressure gauge to check the gas pressure downstream from the valve.
·
Checking the voltage on the card (X6, 3/4) that should vary between 25 and 55V
DC
.
Note that with very low pressure upstream from the valve, opening the valve may be slow and the boiler
could shut down due to failed ignition.