Each boiler in a group needs a position number, defined by parameter SYS-01, starting with “1” and ascending without gaps.
In a heating system with multiple boilers, the boilers can be arranged into groups and will be controlled in sequence or parallel, according to the configuration of the heating control strategy.
With the parameters ST1-01 and ST1-02 the minimum on and off times of Stage1Cmd are defined. The parameters ST1-03 and ST1-04 define the Stage1Cmd blocking times for the next stage or boiler on or off. For Stage2Cmd these parameters are respectively ST2-01, ST2-02, ST2-03 and ST2-04.
The figure shows the operation of the blocking signal for a staged heat generators:
Fig. 2. Blocking times for a staged heat generator
When the minimum on time (ST1-02 or ST2-02) is over and the heat generator stage switches off, the blocking time (ST1-04 or ST2-04) to switch on other heat generators will be reset.
When the minimum of time (ST1-03 or ST2-04) is over and the heat generator stage switches on, the blocking time (ST1-05 or ST2-05) to switch off other heat generators will be reset.
Table 8. Blocking signal values
Value DISP-01 |
Function |
0; 1 |
no blocking |
2 |
blocking increasing the number of stages |
3 |
blocking decreasing the number of stages |
4 |
blocking increasing and decreasing the number of stages |
When a boiler is in operation, the boiler specific minimum supply temperature, defined by parameter BST-04 is transmitted to the heating control strategy macro, to maintain the required boiler temperature limits within the whole heating system.
When a boiler is in operation, the boiler specific minimum return temperature, defined by input “RetTempSp” is transmitted to the heating control strategy macro, to maintain the return temperature only if minimum return temperature control was configured (SYS-02 = 1).
For details of grouping, sequencing and cyclic changeover of the heat generators, please refer to the documentation of the heating control strategy.
Table 9. Parameter List
Description |
Value Range |
Default Value |
Unit |
BST-04: minimum boiler supply temperature |
0...500 |
10 |
°C |
ST1-02: minimum on time stage 1 |
0...3600 |
240 |
sec |
ST1-03: minimum off time stage 1 |
0...3600. |
240 |
sec |
ST1-04: blocking time to switch on next stage or boiler |
0...3600 |
600 |
sec |
ST1-05: blocking time to switch off next stage or boiler |
0...3600 |
300 |
sec |
ST2-02: minimum on time stage 2 |
0...3600 |
240 |
sec |
ST2-03: minimum off time stage 2 |
0...3600 |
240 |
sec |
ST2-04: blocking time to switch on next stage or boiler |
0...3600 |
300 |
sec |
ST2-05: blocking time to switch off next stage or boiler |
0...3600 |
300 |
sec |
SYS-01: position number |
1...16 |
1 |
- |
SYS-02: configuration boiler type 1 = minimum return temperature control 2 = maximum return temperature control 3 = no return temperature control |
1...3 |
3 |
- |