Danfoss DHP-A Service Instructions Manual page 35

The two parameters that are mainly changed are DEFR CURVE 0 and DEFR CURVE -20. The numbers behind the
DEFR CURVE display what outdoor temperature the setting is for, that is to say at 0°C for DEFR CURVE 0 and -20°C
for DEFR CURVE -20. The value -20 for DEFR CURVE -20 is the set value for OUTDOOR STOP, so if the value for OUT-
DOOR STOP changes, the numbers behind DEFR CURVE also change.
Factory setting for OUTDOOR STOP is -20°C. At this outdoor temperature, compressor operation is stopped and
the additional heater takes over. Generally the value of OUTDOOR STOP does not need to be changed. Tests and
operating cases have shown that -20°C operates very well as the stop temperature. In the text and figures below
the value -20°C has been used for OUTDOOR STOP.
The display shows the value for DEFR CURVE 0 and DEFR CURVE -20 by means of a graph.
1
0
-1 6
4
-3 2
-2 5 -1 5
Figure 27. Graph that shows how the value for DEFR CURVE 0 can be set.
1. Temperature, input brine line
2. Adjustable interval for DEFR CURVE 0 is a brine return between -5°C and -15°C at 0°C outdoor temperature
3. Outdoor temperature
4. Set value for DEFR CURVE -20
The value for OUTDOOR STOP corresponds to the fact that the compressor will no longer be used for heating or
hot water production if the outdoor temperature is the same as or lower than the value. Heating and hot water
production will then be produced with the help of the auxiliary heater.
The value for DEFR CURVE 0 is the temperature that the brine return is permitted to reach when a defrost must
start at outdoor temperature 0°C.
In the corresponding way the value for DEFR CURVE -20 is the temperature that the brine return has when a
defrost should start at the set outdoor temperature for OUTDOOR STOP. The setting for DEFR CURVE –20 means
that the value OUTDOOR STOP (-20°C) is reduced by between 1 and 8 degrees. This also determines how much
lower the temperature for the brine return may be than -20°C in this case.
1
0
-16
5
-32
-25 -15
4
Figure 28. Graph that shows how the value for DEFR CURVE -20 can be set.
1. Temperature, input brine line
2. Set value for DEFR CURVE 0
3. Outdoor temperature
4. Set value for OUTDOOR STOP, -20°C
2
3
-5 5
2
3
-5 5
Service instructions VMGFC302 – 33