81
ENG
µchiller +0300053EN rel. 2.2 - 14.12.2021
Functions
The auxiliary heater works mainly to supplement the main control, but also remains active for frost protection. In the event of
frost protection, when both auxiliary and frost protection heaters are installed, both outputs will be active.
Up to two heaters are available, however with the following confi guration required:
• heater 1 confi gured on circuit 1
• heater 2 confi gured on circuit 2 using the I/O expansion
Code Description Def Min Max UOM
F014 Off set on set point in heating mode for the heaters 3.0 0.0 99.9 °K
F015 Diff erential on set point in heating mode for the heaters 1.0 0.2 99.9 °K
F016 Heaters active during defrost (0= No, 1=Yes) 001-
F028 Air heating: probe for user heater temperature control
0 = ROOM
1 = SUPPLY
001-
Tab. 5.l
5.22 Condensing unit management
Chiller can manage condensing units with one or two circuits, air- or water-cooled, in cooling-only mode or reverse cycle with
defrost. The mode is set using parameter U077.
Compared to a chiller unit, the condensing unit does not manage circulation of the primary fl uid (pump, fl ow switch, etc.)
The control signal can be sent to the condensing unit in two ways:
• via BMS (not available on Legacy models)
• via digital inputs
Request via BMS
The request is written by an external device to register HR 331. If the unit is offl ine, the request is overridden to 0% and the
devices are turned off .
Request via digital inputs
There is a digital input for each compressor. Activation of the digital input corresponds to a control step request. The Chiller
application manages rotation between steps, stop due to alarms, and timings.
For Legacy models only, the direct relationship between request digital inputs and compressor digital outputs can be set using
parameter F023. In this case, rotation of the steps must be managed externally.
User Code Description Def Min Max UOM
S F023 Direct relationship DI - compressor DO (MC only) 0=No, 1=Yes 001-
5.23 Automatic changeover (Legacy model only)
This function is used to switch automatically between cooling/heating modes based on the selected probe.
When automatic changeover is enabled, summer/winter seasons are ignored..
The function is only available for the Legacy model.
The following table shows the parameters used to manage this function.
Code Description Def Min Max UOM
U083 Changeover type
0: disabled
1: outside air temperature;
2: air return temperature (air/air units only)
3: delivery water temperature (air/water or water/water units only)
003-
U084 Changeover threshold (type 1 only) 23 -99.9 99.9 °C/F
U085 Changeover dead zone 2 0 99.9 °C/F
U086 Automatic changeover set point minimum limit 0 -99.9 999.9 °C/F
U087 Automatic changeover set point maximum limit 80 -99.9 999.9 °C/F
U035 Automatic changeover delay 15 0 999 Min
SEtU Automatic changeover set point (types 2 and 3 only) 23 U086 U087 °C/F
Tab. 5.d
The operating mode selection diagrams are shown for each single case.
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