Commissioning Multi-DENCO
104 FläktGroup DC-2013-0101-GB • Subject to modifications • R5-08/2020
8.3.4 Calibration of control sensors
Recommendation: If suitable cooling demand can be provided to the unit from within the controlled space
during commissioning, then at this point in the procedure would be appropriate to
change the set-point and other variables to the requirements of the end-user. Details
of how to change values in the C5-12 controller are available in the Multi-DENCO con-
trols manual.
Once the unit is enabled and operating, calibration of control sensors is vital to ensur-
ing an accurate and efficient operation of your Multi-DENCO unit. These sensors in-
clude (but are not limited to):
– Control temperature and humidity sensors – all fitted within the unit
and/or remotely
– Pipework pressure and temperature sensors
– Floor void air pressure control (APS) sensors
– Ambient temperature sensor
These sensors must be calibrated accurately to allow for a successful commission to
be completed. Failure to calibrate these sensors may lead to inefficient operation or
possibly alarms and non-operation.
8.3.5 Commissioning refrigerant circuits
Consideration and Targets
Below are the commissioning targets for an optimum system charge:
Superheat: 7 - 9 K (Default set point = 8 K)
Sub-cooling: 5 - 8 K
Discharge superheat: Compressor(s) at Low Speeds (< 50 RPS) = 15 - 25K
Compressor(s) at High Speeds (> 50 RPS) = 25 - 35K
All 3 of these variables must be considered together for a successful commissioning.
You must also consider/witness what these variables will be at different operating con-
ditions (e.g. low demand vs high demand).
NOTE!
When commissioning a refrigerant circuit for a Multi-DENCO unit it is important that
the compressors are operating at a high speed. Once the high speed is achieved,
time should be allowed for the system to stabilise.
NOTE!
If fitted, it is important to consider the state of BOTH compressor speeds to under-
stand the unit's operating level. For example, an inverter compressor may be oper-
ating at low speeds (< 50 RPS), but if the other compressor is active then the unit
will be operating at above 50% capacity. Compressor speeds can be viewed in the
'Engineering level' of the C5-12 controller display.
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