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© STULZ S.p.A. – all rights reserved EN/06.2016/i01
WPA ExPlOrEr OrIGINAl INSTrUCTIONS
if existent, can give information about changes of the water quantity. A lack of water in the circuit
is replaced by air, which reduces the heat capacity of the chilled water circuit and is detrimental
to the pump.
8.5.2 Evaporator
To be checked: evaporator, inlet/outlet/antifreeze sensors
Check the water side pollution of the tube evaporator by comparing the chilled water inlet tem-
perature to the chilled water outlet temperature. At full cooling capacity, if the difference is less
than 3 K, it indicates a limited heat transmission and thus pollution.
Another possibility to verify this consists in the comparison of the chilled water outlet tem-
perature with the saturated evaporation temperature (by measuring the suction pressure at the
low pressure side of the compressor). If this difference exceeds 7 K, the evaporator is probably
polluted.
In this case the evaporator has to be cleaned chemically by authorized staff.
In case of exchanging or replacing the antifreeze heater in the evaporator the water glycol mix-
ture must be evacuated and collected.
8.5.3 Differential pressure switch
To be checked: differential pressure switch
Check the correct function of the differential pressure switch by step wise closing a shut-off
valve on the inlet of the cooling water circuit, while the compressors are not running.
8.6 Electric circuit
To be checked: power board, electric components, motor
• Check for any faults in the current consumption of the engines.
• Check for possible overheating of the motors of the pump.
8.6.1 Powerboard
The powerboard is provided with a forced cooling system consisting of two ventilated grids with
filter. Check for proper operation of the fans and the efficiency of the filters. If necessary, pro-
ceed replacing the faulty parts.
8.7 Unit in general
To be checked: whole the chiller
• Clean the unit's inside with a vacuum cleaner. Clean pipes simplify the check for leaks.
• Check the pipes, the compressor and the condenser for a tight seat. Vibrations of pipes and
circuit components can result in leaks.
• Check also the insulation of the water piping. Condensing air humidity on cold water pipes
means a loss of cooling capacity.
• Check for loose parts that cause an increase in noise and vibration.
