System Supply/ Return Temperature Setpoint Calculation

When the maximum value of heat demand at the input “HeatDemandIn” and the minimum supply temperature is less than SST-05, the heat demand transmitted to the heat generators will take the value zero.

If this heat demand exceeds the value SST-05 + 3K, the calculated system supply temperature setpoint is the highest value of the following signals:

This setpoint is increased by parameter SST-03, e.g. 5K, to compensate transmission losses. To prevent the system from heating up too fast the calculated setpoint is always ramped up with the increase rate, as defined by parameter SST-04. This setpoint is limited between the minimum and maximum system supply temperature values, respectively defined by parameters SST-01 and SST-02. The ramping up is shown in the next figure.


The effective heating setpoint is displayed at the output “DispEffHtgSp”.


ATTENTION:

When SST-01 is greater than SST05, there will always be an active heat demand and the strategy will keep the minimum system supply temperature. To save energy take care that SST-01 is alway less than SST-05 whenever possible.

Fig. 2.   Heat demand setpoint ramp

Table 1.   Parameter List

Description

Value Range

Default Value

Unit

SST-01: minimum supply temperature

0...500

10

°C

SST-02: maximum supply temperature

0...500

90

°C

SST-03: setpoint raise

0...50

5

K

SST-04: maximum setpoint increment per minute

1...1000

25

K

SST-05: minimum heat demand to start heat generators

0...150

20

°C