User's Manual

T HERMO 90 / 90 S 3FUNCTIONAL DESCRIPTION
3-1
3. Functional Description
(Fig. 3-1)
3.1 Switch-on
When operating the push button "Immediate Heating",
the "Operating Indicator" on the timer illuminates
or
by activation with the switch, the “Operating Indicator”
integrated in the switch illuminates.
Circulation pump, glow pin, and combustion air fan are
put into operation.
3.2 Heating Operation
After approx. 50 seconds, combustion commences with
the automatically controlled heating operation in full load
for a maximum of 2 hours.
The vehicle's own heating blower starts to operate only
after the heat carrier (coolant) has accumulated enough
heat. After reaching the pre-coded rated temperature
(see table Control Temperatures) heating performance,
precision control will take over in stages down to the
lowest part load operation.
3.3 Control Operation
If the coolant temperature rises up to the control idle
threshold, the heater enters the control idle phase.
The circulation pump, the vehicle's own blower, and the
operating indicator remain in operation during the control
idle period.
After the coolant has cooled down to the pre-coded
reactivation temperature, the heater resumes operation.
Diesel Operated Coolant heaters
If the coolant heater's coolant temperature is above the
rated temperature but has not yet reached the threshold
for control idle, with the temperature dropping within 10
minutes back to rated temperature (after reaching it for
the first time), the coolant heater reverts to the 9.1 kW
(31,000 Btu/hr) heating stage. Should the rated
temperature be obtained after 10 minutes, there will be
an automatic reactivation to a maximum performance
output of 7.6 kW (26,000 Btu/hr).
Gasoline Operated Coolant Heaters
The maximum heating performance of gasoline operated
coolant heaters is always 7.6 kW (26,000 Btu/hr).
3.4 Switch-off
When switching the heater off, the operation indicator on
the timer/switch extinguishes. Combustion ends and the
run-down cycle is initiated. The circulation pump and
combustion air fan, however, continue operation to cool
down the heater (run-down) and are automatically
deactivated after about 90 seconds. A reactivation of the
heater during run-down is permitted.
Room temperature control by means of the vehicle's own
heating blower may be provided in addition to employing
a room thermostat.