ICE CUBE MAKERS VERTICAL EVAPORATOR SYSTEM

Transcription

1 ICE CUBE MAKERS VERTICAL EVAPORATOR SYSTEM Last Update: 20/12/2002 VM Line The following diagram shows the main concepts of the ice cube makers working ( vertical evaporator system): Compressor Evaporator Air Condenser Water 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. 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. 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.

2 Reffrri igerratti ing Cirrcui itt 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.

3 Reffrri igerratti ing Cirrcui itt (Coomppoonneennt ( tss) ) 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. 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. 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. 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.

4 Reffrri igerratti ing Cirrcui itt (Prroodduucct ( tioonn Cyyccl lee) ) 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.

5 Hydrraul lic Cirrcui itt 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.

6 Electtrri ic Cirrcui itt 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 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 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 next page shows the timer phases and explains when it does not control the remote control switch.

7 Electtrri ic Cirrcui itt (TTi ( imeerr Staat tuuss) ) 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 evaporator thermostat, by perceiving a drop in temperature of the evaporator, starts up the timer, so to complete the ice production phase. 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 temperature rise (due to the circulation of hot fluid), starts up the timer again, so to complete the defrosting phase.

8 Electtrri ic Cirrcui itt (Coomppoonneennt ( tss) ) 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. Evaporator thermostat It controls the evaporator temperature and drives the timer, as previuosly described. 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 systems 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. 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. 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.

9 Worrki ing Scheme (Ai( irr Veerrssi ioonn) )

10 Worrki ing Scheme (VM ( Waat teerr Veerrssi ioonn) )

11 Worrki ing Scheme (VM ( Waat teerr Veerrssi ioonn) )

12 Check out Procedure for Service for VM Anomaly THE ICE MAKER DOESN T WORK 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 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 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

13 Anomaly THE ICE MAKER DOESN T SPRAY WATER 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 Anomaly THE ICE MAKER STOPS BY INTERVENTION OF THE SAFETY PRESSURE-SWITCH 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 Check the fan motor. If necessary, replace it. Check the correct working of the pressure switch Anomaly THE ICE MAKER REMAINS IN THE DEFROSTING PHASE Faulty evaporator thermostat Replace the evaporator thermostat Check the electric feeding The hot gas valve doesn t open Replace the valve coil Replace the valve Timer locked Replace the timer Anomaly NOT REGULAR OR INCOMPLETE DEFROSTING Lacking refrigerant charge Find the leak, repair it, make vacuum and charge Not adjusted evaporator thermostat Adjust or replace

14 Anomaly SHEET OF ICE UNDER THE EVAPORATOR 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 Inlet or outlet pipe not connected Check connections Slack pipe clips Check the clamp of the clips Anomaly IRREGULAR OR OPAQUE ICE CUBE Water supply too calcareous Spray nozzles badly lined up or dirty Clean or direct the water jet toward the middle of the ice cubes

15 Anomaly COMPRESSOR: PROTECTION INTERVENTION (Intermittent Working) Check: continuity, Faulty power supply the current carrying in Amp., voltage of the electrical circuit. Check: cleaning of the condenser, Difficult condensation 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 Extreme mechanical wear Replace the compressor Anomaly NOISY PUMP Worn bearings Replace the pump

16 Anomaly THE PUMP DOESN T RUN 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 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 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