To avoid calcification of the heat exchanger, the heat exchanger can optionally limit the primary supply temperature. This function is disabled when you add this macro to your control loop since the default input value is "999".
To enable this function, connect:
For an effective calcification protection, set the setpoint value of this point to max. 58 °C.
During legionella protection, the primary supply temperature control is temporarily suspended. Depending on the calculated P-band and the primary supply temperature setpoint, the valve control signal varies from the valve position limit VLV-01 to 100% as shown in the next figure.
Fig. 4. Primary Supply Temperature Limitation
NOTE: |
This function can also be used to limit the maximum valve position at high system supply temperature in district heating systems. |
In this case:
Table 2. Parameter List
Description |
Value Range |
Default Value |
Unit |
PST-01: P-band primary supply temperature control |
0...100 |
15 |
K |
VLV-01: valve position limit |
0...100 |
100 |
% |