NGW 300 / LGW 300 / GBW 300
2 General description
203
Thermostat valve
2.2.2 Delayed-action solenoid
(only for the NGW 300)
The delayed-action solenoid is necessary at gas supply
pressures of 8 bar for the safe functioning of the input so-
lenoid valve on the gas pressure regulator.
The solenoid is installed in the gas hose from the gas pres-
sure regulator to the heater and is connected electrically in
series to the solenoids in the gas pressure regulator.
After the solenoids in the gas pressure regulator are ope-
ned, the delayed-action solenoid releases the gas flow to
the heater with a second’s delay.
For higher gas supply pressures, the delayed-action sole-
noid can be installed as an additional safety element.
The delayed-action solenoid is a basic integral part of the
GBW 300, version NGW.
Delayed-action solenoid
2.3
Heat exchanger
In the heat exchanger, the heat produced by combustion
is transferred to the coolant circuit.
2.4
Combustion chamber
The gas-air mixture is distributed in the combustion cham-
ber and is burned there. The heat exchanger and the coo-
lant flowing through it are heated by this process.
2.5
Control unit
The control unit guarantees the function sequence and
monitoring of the firing operation.
The SG 1578 control unit for the NGW 300 and LGW 300
heaters is no longer available and is being replaced by the
modified SG 1585 control unit.
When refitting, the appropriate vehicle-specific adapter
wiring harness is required.
The GBW 300 heaters are already equipped with the SG
1585 control unit.
2.6
Flame monitor electrode
During the entire firing operation, the state of the flame is
monitored by the flame monitor electrode. By means of io-
nisation of the air, depending on the temperature (flame),
the signal is changed at the flame monitor electrode and
processed by the control unit.
0-90°
0-90°
0-90°
0-90°
SG 1578
SG 1585
Flame monitor electrode
Ignition electrodes
