This function is required in case of district heating applications. The heating circuit return water temperature (RWT) can be limited by a maximum setpoint, in order to override the heating valve output to close, if the return water temperature becomes too high. The relationship between the calculated return water setpoint and the outside air temperature is shown in the next figure. The calculated return temperature setpoint is displayed in the setting DISP-04 and the macro output "CalcRetTmpSp".
Fig. 13. Return water temperature setpoint
Depending on the P-band RWT-05, the I-time RWT-06 and the calculated return water temperature setpoint, the control signal varies from 0...100% as shown in the next figure.
Fig. 14. Return water temperature control
Table 17. Parameter List
Description |
Value Range |
Default Value |
Unit |
|
RWT-01: min. OAT RWT control |
-50…150 |
-10 |
°C |
|
RWT-02: max. OAT RWT control |
-50…150 |
10 |
°C |
|
RWT-03: low setpoint |
0…150 |
65 |
°C |
|
RWT-04: high setpoint |
0…150 |
85 |
°C |
|
RWT-05: P-band RWT control |
1…50 |
10 |
K |
|
RWT-06: I-time RWT control |
0…3600 |
0 |
sec |
|
DISP-04: calculated return water temperature setpoint |
0…150 |
- |
°C |