Thermo 90 S / Thermo 90 ST 3 Function description
301
3 Function description
(Fig. 301)
3.1 Switching on
The “operating indicator” on the digital timer lights up
when the “immediate heating” button is pressed.
or
When switching on with the switch, the operating indicator
in the switch lights up.
The circulating pump, glow plug and combustion air fan
start operating.
3.2 Heating mode
Combustion starts after approx. 60 to 140 seconds.
Automatically controlled heating operation runs at full load
for a maximum of 2 hours.
The vehicle’s own heater fan does not switch on until the
heat carrier (coolant) has heated up sufficiently. Once the
preset nominal temperature has been reached (see table
of regulating temperatures) the heating power is reduced
to the lowest part load in small individual steps.
3.3 Control mode
The heater switches to the control pause if the
temperature of the coolant continues to rise to the
threshold of the control pause. The circulating pump, the
vehicle’s own heater fan and the operating indicator
continue to operate during the control pause.
The heater restarts when the coolant cools to the preset
temperature for switching back on.
Diesel heaters
If the water temperature in the heater is higher than the
nominal temperature but has not yet reached the
threshold for the control pause and if the temperature then
falls back to the nominal temperature within 10 minutes
(after reaching this temperature for the first time), the
heater switches back to the 9.0 kW heating stage.
When the nominal temperature is reached, the heater is
only switched back on again up to the 7.6 kW heating
stage.
Petrol heaters
The maximum heating power in petrol heaters is
always 7.6 kW.
