Webasto thermo top evo Workshop Manual - Thermo Top Evo
Thermo Top Evo
3 Description of operation
301
3
Description of operation
3.1
Switching on/starting process
The heater is started with the parking heater via a switch-on
signal of the heater control. And with the auxiliary heater
when the auxiliary heating signal is present at the heater
unit inlet. The auxiliary heating signal is dependent on pre-
viously defined switch-on conditions, such as the outside
temperature (below 5 °C) and engine running.
NOTE
The Thermo Top Evo heaters described in this manual can
only be put into operation with a W-bus-capable heater
control, or with the Webasto Thermo Test PC Diagnosis.
With the Webasto Thermo Test PC Diagnosis connected, the
connection to other heater controls is disconnected.
Different configuration options are shown in the system wir-
ing diagram.
When the heater is started up, the combustion air fan, the
circulating pump and the glow plug are put into operation.
Then the metering pump is connected. The petrol heater
starts up at the highest load level. In contrast, the diesel
heater starts up at a low load level and is slowly adjusted
upward to full load in the form of a ramp.
During this start-up phase, it is checked whether a flame has
formed with the glow plug. If no flame is formed or the
flame extinguishes, then automatic restarting can be initi-
ated. If no flame is formed once again, the starting attempt
is ended. Then a fault lock-out is carried out with run-on of
the combustion air fan. The heater cannot be restarted until
after switch-off.
Depending on the coolant temperature, the control unit
decides which starting process is selected. Start-up proc-
esses are identical with regard to the sequence, however
differ in the length of the individual phases (preheating, fuel
delivery, etc.).
3.2
Heating mode
After full load is reached, the glow plug assumes the func-
tion of the flame monitor and checks the flame. The heater
switches into the energy-saving partial-load mode after a
certain temperature (around 80 °C) is reached. If the tem-
perature continues to increase, the heater switches into the
control break from a pre determined temperature (approx.
84 °C).
After the coolant has cooled down, the heater restarts in the
partial-load mode. If the temperature rises to a defined
switching temperature again, the heater switches into the
control break again.If the temperature of the coolant con-
tinues to drop due to an increased heat requirement during
partial load operation, then the heater switches over to full
load operation again.
The temperature of the switching points is programmed in
the control unit.
If a flame out occurs during normal combustion operation,
a restart is automatically initiated.
Fig. 301 Functional illustration of Thermo Top Evo heater
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