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Access 4.x |
Changeover configuration example |
Changeover is a separate unit providing both heating and cooling on demand. The changeover is a standalone unit with separate controller present. The demand for heating or cooling is switched and regulated from the hardwired Access controller.
The table below shows a configuration example of the changeover unit.
Variable |
Available options & Selection |
Note |
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Sequence selection |
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Configuration > Functions > Function activation > Heating/Cooling sequence setup |
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Sequence for heating |
|...| SEQ-G Heating 2 | SEQ-H |...| |
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Sequence for cooling |
|...| SEQ-G | SEQ-H Cooling 2 |...| |
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Sequence settings |
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Configuration > Functions > Function activation > Heating/Cooling sequence setup > Heating 2 |
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Type of sequence |
|...| Heating |...| |
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Type of heater |
| Water | Electric| DX | Combi coil | |
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Type of feedback |
| None | Alarm | Run indication | |
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Digital start output |
| No | Yes | |
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Sequence output when recirculation/support |
| 0% | 100% | Auto | |
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Sequence output min limit |
0% |
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Sequence output max limit |
100% |
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Sequence output when the unit is stopped |
0% |
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Configuration > Functions > Function activation > Heating/Cooling sequence setup > Cooling 2 |
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Type of sequence |
|Cooling |...| |
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Type of cooler |
| Water | DX | DX with exchanger control | |
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Type of feedback |
| None | Alarm | Run indication | |
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Digital start output |
| No | Yes | |
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Sequence output when recirculation/support |
| 0% | 100% | Auto | |
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Sequence output min limit |
0% |
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Sequence output max limit |
100% |
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Sequence output when the unit is stopped |
0% |
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Changeover settings |
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Configuration > Functions > Function activation > Heating/Cooling sequence setup > Changeover settings |
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Changeover 1 |
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Changeover sequence for heating |
… | Disabled | … |
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Changeover sequence for cooling |
… | Disabled | … |
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Changeover 2 |
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Changeover sequence for heating |
… | Heating 2 | … |
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Changeover sequence for cooling |
… | Cooling 2 | … |
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PID Settings |
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Configuration > PID controllers > Heating 2 |
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P-band |
10 oC |
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I-time |
100 s |
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D-time |
0 s |
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Configuration > PID controllers > Cooling 2 |
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P-band |
10 oC |
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I-time |
100 s |
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D-time |
0 s |
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Hardwired interface to the pump & valve |
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Configuration > I/O allocation settings > |
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Digital inputs > Feedback Heating 2 (SEQ-G) |
Any available I/O |
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Digital inputs > Feedback cooling 2 (SEQ-H) |
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Digital inputs > Cooling/(Heating) changeover 2 |
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Digital inputs > Lock PID controller supply |
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Digital outputs > Cooling 2 start (SEQ-H) |
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Digital outputs > Changeover 2 |
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Analog outputs > Changeover 2 |
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Heater starting and stopping |
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Data & Settings > Temperature control > Heating 2 |
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Digital start output start point |
10% |
Output of the supply controller to start and stop the heater |
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Digital start output stop point |
1% |
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Cooling control settings |
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Data & Settings > Temperature control > Cooling 2 |
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Digital start output start point |
10% |
Output of the supply controller to start and stop the DX cooler |
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Digital start output stop point |
1% |
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Block DX-cooling if outdoor temperature < |
0 oC |
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Block DX-cooling if supply air fan output signal < |
0% |
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Hysteresis if outdoor temperature block |
1 oC |
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Reduction of min limit supply air if active DX-cooling |
5 oC |
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Graphical representation |
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Flowchart |
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58 % - indicates the output of either Heating 2 sequence or Cooling 2 sequence (depending if there is a demand for heating or cooling) |
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Chapter info
Last reviewed: 06/21/2022
Access version: 4.6-1-02 (3354)