Heating operation
*
1
*
2
Return temperature (HEA): max. 45.0 °C (standard setting 40.0 °C)
Flow temperature: Return temperature plus 5 to 8 K
Cooling operation
*
3
Return temperature (Coo): approx. 12.0 °C (standard setting 12.0 °C)
Flow temperature: Return temperature less 5 to 8 K
Checking the superheating and correcting, if required
(cooling mode)
The unit is equipped with a thermostatic expansion valve with external pressure
compensation. At the factory, the expansion valve is set to 5 K superheating.
Checking the superheating
To ensure adequately accurate test
values, start the unit at least 5 min-
utes before the test is started.
1. Determine the low pressure with
the pressure gauge attached to the
inlet side of the service valve (see
Fig. on page 7 and 8).
2. Using the temperature scale of the
pressure gauge, determine the
saturation temperature of the inlet
side (Tse) that corresponds to this
pressure.
3. Place a contact thermometer at the
outlet connector of the evaporator
and determine the effective tem-
perature (Tsa).
4. Calculate superheating S from
Tse – Tsa.
5. Record the determined values in
the service report from page 46.
Adjusting the superheating
1. Rotate the adjusting screw of the
thermostatic expansion valve by up
to ½ turn.
2. Let the unit run for at least 5 min.
3. Recheck the superheating.
4. If required, repeat steps 1 to 3.
Note
Should the thermostatic expansion
valve fail to respond to the superheat-
ing adjustment, it may be stuck or
faulty and may need to be replaced.
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