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© STULZ S.p.A. – all rights reserved EN/06.2016/i01
WPA ExPlOrEr OrIGINAl INSTrUCTIONS
7.2.3 Commissioning of the refrigerant circuit
• Switch on the circuit breakers of compressors.
• Adjust the desired set point of the water temperature at the controller
• Start the chiller unit by pressing the Start/Stop-key on the controller.
• Check after 20 minutes of operation at full load, whether gas bubbles are visible in the sight
glass of the liquid line. If this is the case, refrigerant might have escaped by a leak.
Check the circuit on leaks, eliminate them and fill the circuit with R410A according to the
chapter "8 Maintenance" at page 67.
• Check the current consumption of the compressors and the condenser fans comparing it with
the values in the technical data.
• Check the oil level at compressors respects the right level. The oil sight glass is installed at the
compressor. The oil level should be between the lower quarter and the upper quarter of the
sight glass.
• Connect gauges at the high pressure and low pressure side and verify by reading the pres-
sures, that the saturation temperatures for evaporation (low pressure side) and condensation
(high pressure side), which correspond to the measured pressures, are within the following tol-
erances during the operation.
High pressure side
: max. 18 K above the air intake temperature of the condenser
low pressure side
: 3 to 7 K beneath the chilled water flow temperature
The pressure gauges feature a scale on the innermost ring indicating the saturation tempera-
tures belonging to the pressures.
Example:
Measured on the high pressure side: 13 bar (rel.) (= 14 bar abs.) corresponding saturation
temperature at the dew point according to scale for R134a: 52,5°C measured air intake tem-
perature at the condenser: 35°C
t
cond
- t
air
= 52.5°C - 35°C = 17.5 K
ok
measured on the low pressure side: 2.5 bar (rel.) (= 3.5 bar abs.) corresponding saturation
temperature at the dew point according to scale for R134a: 5.0°C measured flow water tem-
perature at the evaporator outlet: 12°C
t
flow
- t
evap
= 12°C - 5,0°C = 7 K
ok
If the tolerances (18 K at the condenser, 7 K at the evaporator) are exceeded, there is a prob-
lem of heat transmission. The probable cause is the pollution of the heat exchage surfaces.
Also the superheating may be set too high.
