ICE CUBE MAKERS “VERTICAL EVAPORATOR” SYSTEM
Last Update: 20/12/2002
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The following diagram shows the main concepts of the ice cube makers
working (‘vertical evaporator’ system):
Compressor
Each ice maker uses the properties of compression and expansion of the
liquefiable gases; its main principle is that each change of bodies state
is got by producing or absorbing heat.
More precisely, the change of the refrigerating fluids from the liquid to
the steam state is always followed by heat absorption.
That means that, by placing the machine side, in which the evaporation
takes place, calories are taken away from that ambient, so, giving it
frigories.
Condenser
The steams got after the expansion are then liquefied for compression.
The compressor sucks up the gases, caused by the evaporation, and
compresses them by increasing their temperature and pressure.
A condenser, made up of a series of tubes (refrigerated by cold water
or ventilated air), carries away the heat, comprised in the gas that comes
out from the compressor and, helps, so, the gas liquefacting.
Evaporator
Air
Water
The refrigerating fluid, now in liquid state, circulates, then, in an
evaporator that permits a perfect heat exchange with the out-room, by
taking away calories and producing ice, which is got by means of the
freezing of the water sprayed in the cubes forms by the spray-bar.
The working of this machine is cyclic: ice cubes are produced during
the first phase and fall in the external bin, placed under the machine,
during the second phase.
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The working of this machine is cyclic. Each cycle is carried out into
two phases: ice cubes are produced during the first phase and fall in the
external bin during the second phase.
The following diagram shows the main concepts of the refrigerating
circuit:
Production Phase of the Ice Cubes
The hot gas valve is closed in this phase; the refrigerating fluid, after
having been refrigerated by the condenser, circulates through the
evaporator coil (welded to the cubes basin), by cooling each small
copper cup.
Water is sprayed on the evaporator cubes-basin through the spray-bar
nozzles. An ice layer, due to the refrigerating fluid, begins forming in
the cups, till these are completely full (after some minutes).
Ice Falling Phase (Defrosting)
Once the ice-production time is finished, the spray-bar stops spraying
water on the cubes-basin and the hot gas valve, assembled on the
compressor delivery side, opens.
This opening permits to pipe the refrigerating fluid (now overheated,
after the compression) to the evaporator directly, without letting it pass
through the condenser; the water level in the bin is restored during the
defrosting phase.
Due to such overheated fluid, the evaporator warms up and the ice
cubes, formed in the cups, come out from the cups themselves, falling
in the below bin.
At the end of the defrosting phase, the cycle starts again.
The compressor is always working: during both the production and the
defrosting phase.
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Compressor
It sucks up the gases, caused by the evaporator, by means of a suction
line and compresses them by increasing their temperature and pressure.
Refrigerant filter + capillar tube
The refrigerant filter stops possible impurities and the circuit humidity.
The gas, in liquid status, goes to the evaporator through this filter and
the capillar tube.
Hot gas valve
It controls a “by-pass” circuit that starts from the compressor and
arrives to the evaporator, by excluding the condenser.
The opening of the valve permits to pipe the refrigerating fluid
(overheated after the compression) to the evaporator directly, without
letting it pass through the condenser and warming up the evaporator
itself.
Evaporator
It permits a perfect heat exchange with the water circulating on it and
produces ice by means of the water freezing itself.
It is made up of a series of small tin-plated copper cups, plunged into a
plastics support and welded to a copper coil, where the refrigerating gas
circulates.
Condenser (Air/Water)
If ‘Water’, it is made up of a series of tubes, refrigerated by cold water.
If ‘Air’, it is made up of a radiator, that exchanges heat with the outroom, and is refrigerated by ventilated air, coming from a fan, run by an
electric motor.
Both of them carry away the heat, comprised in the gas that comes out
from the compressor, by helping the gas liquefacting.
Suction line
It permits the refrigerating gas circulation from the evaporator to the
compressor.
The liquid gas is trapped in a specific boiler, that prevents its arrival to
the compressor.
The suction line also controls and keeps constant the circulation of the
gas, coming out from the evaporator.
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Ice cubes production
The hot gas valve (reversal cycle valve) is closed; the compressed gas,
coming out from the compressor, is piped to the condenser, in order to
get cool.
Defrosting
The hot gas valve (reversal cycle valve) is open; the compressed gas,
coming out from the compressor, is piped to the evaporator, by-passing
the condenser.
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The following diagram shows the main concepts of the hydraulic
circuit:
The circuit of water supply of the bin, the Water-inlet valve, the pump
and the evaporator are on all machines of the ‘VM’-line; the circuit of
the water condenser, on the contrary, is on water-cooled versions only.
Water-inlet valve
It is put into action during the defrosting phase. It permits the flow of
the water-supply into the bin, in order to restore the ideal water level, so
as to start a new cycle of ice cubes production.
The second water-inlet valve permits the flow of the water-supply
through the water condenser.
Pump
It draws out water from the bin and pipes it, under pressure, to the
spray-bar.
Spray-bar
It gets water from the pump and, by means of its nozzles, sprays it
towards the cubes basin of the evaporator. The water that does not
freeze, by contacting the copper cups (refrigerated by the evaporator
coil), falls in the inside bin and is drawn by the pump once again.
Static pressure valve (VM500/900 only)
It is assembled only on water cooled machines.
It has to control and keep constant the condensing pressure, by
changing the quantity of water that flows in the condenser.
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The following diagram shows the main concepts of the electric circuit:
The coil of the remote control switch, at its turn, is controlled both by
the timer and the bin thermostat.
The following scheme shows the above connection:
The coil of the remote control switch can be excited both by the timer
and the bin thermostat; only in case these two sources should be
missing, the remote control switch stops the power to the compressor.
The remote control switch gives power to the compressor, that works
continuously, both during the ice cubes production and during the
defrosting phase.
It also gives power to the refrigerating fans, that are controlled by the
condenser pressure-switch.
The next page shows the timer phases and explains when it does not
control the remote control switch.
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Ice cubes production
The timer, in the first phase, starts up the pump and the coil of the
remote control switch:
Defrosting
The timer, once reached the set up time, simultaneously commutes two
contacts, letting the defrosting phase begin.
Some minutes after the beginning of the ice production phase, due to
the refrigerant in expansion in the coil, an ice layer starts to form inside
the cups.
The pump is stopped and also the sprays working stops; on the
contrary, the hot gas valve (reversal cycle valve) is started up,
permitting to pipe the refrigerating fluid (overheated) directly to the
evaporator. The water-inlet valve is started up too.
The evaporator thermostat, by perceiving a drop in temperature of the
evaporator, starts up the timer, so to complete the ice production phase.
The evaporator thermostat, by perceiving a temperature rise (due to the
circulation of hot fluid), starts up the timer again, so to complete the
defrosting phase.
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Controls systems
Hot gas valve – The opening of the valve permits to pipe the
refrigerating fluid (overheated after the compression) to the evaporator
directly, without letting it pass through the condenser and warming up
the evaporator itself.
Safety systems
Evaporator thermostat – It controls the evaporator temperature and
drives the timer, as previuosly described.
Bin thermostats - The bin thermostats can stop the ice machine at two
different levels: high or low. This happens by means of a push selector
switch placed on the right side of the ice machine.
Washing – It is possible to disconnect the compressor by means of the
switch placed on the back of the machine.
Condenser pressure-switch – It controls and keeps constant the
condensing pressure; ref. to the delivery pipe, it drives the refrigerating
fans, placed near the condenser itself (on ‘Air’ versions) and drives the
condensing water-inlet valve (on ‘Water’ versions).
Timer – See previous description.
Safety pressure-switch – It stops the ice machine working,
disconnecting the power flux, when the pressure in the refrigerating
circuit exceeds a preset threshold value.
When the thermostats perceive a drop in temperature (due to the ice
cubes accumulation in the bin), they open the contacts, disconnecting
the power flux, and stop the ice machine working
The machine stop only happens during the defrosting phase, as the
timer keeps a second power flux working during the production phase
and, this, till the phase commutation.
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Check out Procedure for Service for VM
Anomaly
THE ICE MAKER DOESN’T WORK
Cause
Remedy
There is no supply mains voltage
Check the user’s electrical system
Intervention of the safety pressure switch
Reset
Contactor out of order
Replace the contactor
Anomaly
THE ICE MAKER WORKS BUT THE ICE DOESN’T FORM
Cause
Remedy
The ice maker is in the washing-phase and the
compressor is cut out
Restart the compressor, by pressing the switch
on the back side of the machine, under the filter
Ice maker without refrigerant
Find the leak, repair it, make vacuum and charge
Refrigerant blow-by through the hot gas valve
Clean the hot gas valve or replace it
Water blow-by through the evaporator water inlet
valve
Replace the valve
The compressor doesn’t compress
Replace the compressor
Anomaly
THE ICE MAKER REMAINS WITHOUT WATER IN THE BASIN
Cause
Remedy
Overflow-tube in the bin not correctly positioned
Check the right position
Water blow-by through the discharge valve
Clean or replace
Faulty water inlet valve, it doesn’t open or is
clogged
Replace the water inlet valve
Anomaly
THE ICE MAKER DOESN’T SPRAY WATER
Cause
Remedy
The pump is out of order
Check the electric and mechanical pump
efficiency or replace it
Filter of the pump suction clogged
Clean the filter
Limestone inside the pump pipes
Clean the pipes from the limestone
Spray nozzles clogged
Clean the sprayers
THE ICE MAKER STOPS BY INTERVENTION OF THE SAFETY
PRESSURE-SWITCH
Anomaly
Cause
Remedy
No water supply to the ice maker
Check the water supply
Condenser clogged by limestone
Remove the limestone from the condenser
For air-cooled models:
The fan is out of order
Anomaly
•
Check the fan motor. If necessary,
replace it.
•
Check the correct working of the
pressure switch
THE ICE MAKER REMAINS IN THE DEFROSTING PHASE
Cause
Remedy
Faulty evaporator thermostat
Replace the evaporator thermostat
The hot gas valve doesn’t open
Timer locked
Anomaly
•
Check the electric feeding
•
Replace the valve coil
•
Replace the valve
Replace the timer
NOT REGULAR OR INCOMPLETE DEFROSTING
Cause
Remedy
Lacking refrigerant charge
Find the leak, repair it, make vacuum and charge
Not adjusted evaporator thermostat
Adjust or replace
Anomaly
SHEET OF ICE UNDER THE EVAPORATOR
Cause
Remedy
Faulty or not adjusted evaporator thermostat
Replace the evaporator thermostat or adjust it
Refrigerant blow-by through the hot gas valve
Clean or replace the valve
Timer locked
Replace the timer
Evaporator encrusted by limestone
Follow the procedures for the evaporator
cleaning
Ice maker without refrigerant
Find the leak, repair it, make vacuum and charge
Anomaly
WATER LEAKAGES
Cause
Remedy
Inlet or outlet pipe not connected
Check connections
Slack pipe clips
Check the clamp of the clips
Anomaly
IRREGULAR OR OPAQUE ICE CUBE
Cause
Remedy
Water supply too calcareous
Spray nozzles badly lined up or dirty
Clean or direct the water jet toward the middle of
the ice cubes
COMPRESSOR: PROTECTION INTERVENTION
Anomaly
(Intermittent Working)
Cause
Remedy
Check:
Faulty power supply
•
continuity,
•
the current carrying in Amp.,
•
voltage of the electrical circuit.
Check:
Difficult condensation
•
cleaning of the condenser,
•
the fan working,
•
aeration in and out of the ice maker.
Starting capacitor out of order
Replace the capacitor
Compressor starting relay out of order
Replace the relay
Compressor winding discontinued
Replace the compressor
Seizing
Replace the compressor
Anomaly
NOISY COMPRESSOR
Cause
Remedy
Extreme mechanical wear
Replace the compressor
Anomaly
NOISY PUMP
Cause
Remedy
Worn bearings
Replace the pump
Anomaly
THE PUMP DOESN’T RUN
Cause
Remedy
Lack of power supply
Check the contacts of the timer micro-switch
Mechanical locking
Replace the pump
Interrupted winding
Replace the pump
Anomaly
INTERVENTION OF THE USER’S MAIN SWITCH
Cause
Remedy
Compressor: short circuit and/or low dielectric
strength
Replace the component
Pump: short circuit and/or low dielectric strength
Replace the component
Hot gas valve: short circuit and/or low dielectric
strength
Replace the component
Thermostat: low dielectric strength
Replace the component
Other electrical components: short circuit and/or
low dielectric strength
Replace the component
Anomaly
ICE PRODUCTION DECREASE
Cause
Remedy
Overflow-tube in the bin not correctly positioned
Check the right position
Condenser or air filter clogged
Clean the filter and the condenser
Ice maker without refrigerant
Find the leak, repair it, make vacuum and charge
Refrigerant blow-by through the hot gas valve
Clean the valve or replace it
Water blow-by through the evaporator water inlet
valve
Replace the valve
The compressor doesn’t compress
Replace the compressor