8.5.8
INTEGRAL
The heat demand in the house depends on the season and weather conditions and is not constant. The heat
demand can be expressed as temperature difference over time and can be calculated giving an integral value as a
result (heat demand). To calculate the integral value, the control system uses several parameters.
A heat deficit is needed to start the heat pump, and there are two integral values, A1 (default value = -60), which
starts the compressor and A2, (factory set = -600), which starts the auxiliary heater and A3 (user-defined value),
which starts the external auxiliary heater. External auxiliary heater operation is activated when the integral passes
the value for INTEGRAL A3. During heat production, the deficit reduces and when the heat pump stops, the inertia
in the system causes a surplus of heat.
The integral value is a measurement of the area under the time axis and is expressed in degree minutes. The figure
below shows the factory settings for the integral values that the heat pump has. When the integral value has
reached the set value for INTEGRAL A1, the compressor starts and if the integral value does not drop but continues
to rise, the auxiliary heater starts when the integral value has reached the set value for INTEGRAL A2.
1 5
7
3
4
1 4
11
1 3
1 2
3
4
6
1 2
11
8
8
2
5
2
1 0
9
1
5
1 0
9
15
15
16
Position
Description
1
Integral
2
Heat surplus
3
INTEGRAL A1
4
INTEGRAL A2
5
Heating deficit
6
Time
7
Heat pump operation
8
No operation
9
Compressor
10
Aux. heat. + ext. aux. heater
11
Compressor start (A1)
12
Auxiliary heater start (A2)
13
Aux. heater stop (latest by A1)
14
Compressor stop (=0)
Installation instructions VMGFD102 – 43
