Supplied By www.heating spares.co Tel. 0161 620 6677
18
DOMINA F 24 - 30 E
FERELLA F 24 - 30 MEL
MILOS AIR COMPACT E
Version - 09.2002
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 (X6-1/2/3/4) 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:
Check there is gas, and that gas comes out of the valve by means of
screw B.
If there is no gas, you must check there is voltage at the operators. This
makes it possible to understand whether the problem lies with the valve
(there is voltage at the operators) or with the card (there is no voltage
at the contacts X6-1/2/3/4).
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 of the second operator on the card (X6, 1/2). This is the most effective method
in some situations. With this test, it is possible to understand whether the problem lies with the valve
or with the card.
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.
