Integral - Danfoss DHP-A Service Instructions Manual

9.7

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, which starts the exter-
nal auxiliary heater. 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. If the integral value does not reduce but continues
to increase the internal additional heat will start when the integral value reaches the set value for A2 and the exter-
nal value at set value for A3
1
1 5
11
15
1 2
16
9
Figure 25. Starting and stopping heat pump operation based on integral values
Symbol explanation
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 Internal additional heater
11 Compressor start (A1)
12 Auxiliary heater start A2
13 Aux. heater stop (latest by A1)
14 Compressor stop (=0)
2
3
4
1 0
8
5
1 4
11
1 3
2
3
4
15
1 2
1 0
9
8
Service instructions VMGFC302 – 31
5
6
7