MAINTENANCE AND OPERATING MANUAL
Troubleshooting
HAS T 070÷140
95
ENGLISH
EN
The data in this manual are not binding and they can be modified by the manufacturer without notice. Reproduction of this manual is strictly prohibited.
CHAPTER 9
TROUBLESHOOTING
PROBLEM SYMPTOM CAUSE/REMEDY
A
Unit fails to
start
• Unit is powered and yet fails to start. Presence of shut-down alarms
Check for the presence of alarms that prevent the unit from starting.
Unit programmed to run by time band
The unit is set to start only within the programmed time bands.
Activate start mode outside the time bands in the User stage.
Supervision active
Check that supervision is not enabled on the unit.
Enter the supervision stage and disable supervision function.
Remote control active
Disable remote mode to start the unit.
B
Water outlet
temperature
higher than
set-point.
• Unit is operational but water temperature
is higher than the set-point value.
• BTOWT temperature higher than
prescribed value.
• High water outlet temperature alarm trip.
• Low evaporation pressure.
• Presence of a large number of air bubbles
in the liquid sight glass.
• Excessively noisy operation of
compressors.
Water flow rate too high
Increase hydraulic circuit pressure drop (for example: by partially
closing a pump discharge valve).
Thermal load too high
Restore thermal load to within prescribed limits.
Ambient temperature too high
Increase air recirculation.
Condenser fins fouled
Clean the condenser fins.
Front surface of the condenser blocked
Remove the obstruction from the front surface of the condenser.
Incorrect direction of fan rotation
Invert the position of two of the three phase wires of the power
supply.
Circuit has insufficient refrigerant charge
Call in a qualified refrigeration engineer to check for leaks and
eliminate them. Have the circuit charged by a qualified refrigeration
engineer.
Incorrect compressors rotation
Invert the position of two phase wires of the compressors power
supply (see chap. " Start-up").
C
Insufficient
pressure
head (water
pressure) at
the outlet of
the pump
(if present).
• Rise of water outlet temperature.
• With pump installed: pressure difference
(read on the unit pressure gauge) with
pump running and pump stopped is too
low.
• Increase in the pressure drop due to the
presence of ice.
• High temperature difference between
water inlet and outlet.
Water flow rate too high
Restore flow rate to within prescribed limits, for example by
partially closing a pump delivery cock.
Presence of ice in the evaporator
Stop the unit, leave the pump running, edit the set-point value and
add ethylene glycol to the water.
Evaporator blocked
Supply a high flow rate of water in countercurrent conditions.
Install a filter upline from the unit.
D
The unit is
blocked and
water does
not flow.
• No water flow.
• Water differential pressure switch (not
present)/flow switch alarm trip.
• Low pressure alarm trip.
• Suction pressure too low.
Set-point value too low
Increase the SET-POINT value or add ethylene glycol (antifreeze)
in adequate percentage (see heading "4.3.4 Freeze protection").
The formation of ice can severely damage the unit.
E
High
pressure
• High pressure switch trip.
• Refrigerant compressor stops.
• icon illuminates.
• General alarm relay trip.
• Fans stopped or reverse rotation
direction.
• Water outlet temperature too high.
Fans stopped or incorrect rotation
Repair or renew the fan.
Invert the position of two phase wires of the fan power supply.
Warm air recirculation
Change the position of the unit or the position of any nearby
obstructions in order to prevent recirculation.
Coil fouled
Clean the condenser fins.
Thermal load too high
Restore thermal load to within prescribed limits.
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