enhanced refrigeration and water systems review...control system, this new remote scotsman cuber...

Technical Reviewof a

Remote CondenserCuber

with

EnhancedRefrigeration and

Water Systemsusing

CM3

Technologymodels included are:

CME456,CME1056,CME1356,

CME1656 andCME2006

CME1356 shown on BH900

Headmaster

Remote Condenser

Liquid Line

HarvestBypass

ValveDischargeCheck Valve

LiquidCheck Valve

Receiver

Accumulator withHeat Exchange

Thermostatic Expansion Valve

Hot GasValve

Inlet WaterValve

Water Pump

Purge Valve

Refrigerant Distributor

Discharge Line

Discharge Line

SuctionLine

Compressor

LiquidLine

Evaporators

SuctionManifold

Freeze Cycle

Scotsman’s new enhanced refrigeration system has been designed to deliver long termreliability as well as competitive performance. Combined with the state of the art CM3

control system, this new remote Scotsman cuber will consistently deliver ice under a verywide range of conditions.

While in a Freeze Cycle in typical summer conditions, the refrigeration system operatesmuch like a self contained air cooled - except that it exhausts the heat outside the icemachine cabinet.

New Remote Cuber Technical Review

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Headmaster

Remote Condenser

Liquid Line

HarvestBypass


LiquidCheck Valve

Receiver



Hot GasValve

Inlet WaterValve

Water Pump

Purge Valve


Discharge Line

Discharge Line

SuctionLine

Compressor

LiquidLine

Evaporators

SuctionManifold

Remote systems function like regular air cooled models under warm conditions. It’s whenthe temperatures get cold that the system must change to keep ice flowing into the bin.

When the remote condenser operates in cold air, the machine adjusts for that in part bylimiting the amount of refrigerant that will be used during a harvest cycle. Additionally thereis a “headmaster” valve in the condenser. During the Freeze cycle it maintains a minimumdischarge pressure - even when the condenser is operating in a sub-zero environment.Maintenance of a minimum discharge pressure allows a remote condenser ice machineto continue to make ice under extreme low temperature conditions.

The “Headmaster” valve shuts off liquid flow out ofthe condenser, causing an increase in the amount of

liquid refrigerant in the condenser. This lowers theamount of liquid refrigerant in the receiver. Dischargegas from the ice machine is routed to the liquid line to

keep the system pressurized and making ice.

Freeze Cycle -Cold Ambients


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Headmaster

Remote Condenser

Liquid Line

HarvestBypass


LiquidCheck Valve

Receiver



Hot GasValve

Inlet WaterValve

Water Pump

Purge Valve


Discharge Line

Discharge Line

SuctionLine

Compressor

LiquidLine

Evaporators

SuctionManifold

BeginningHarvest Cycle

This system uses check valves to keep some of the refrigerant in the condenser, containingthe cold refrigerant where it cannot take heat away from the hot gas used for harvest. Thisalso keeps the compressor, and its oil, warmer, which improves compressor reliability.

Because some additional refrigerant is needed during harvest, a by-pass solenoid opensfor a few seconds to inject a small amount of discharge gas refrigerant into the suctionside, where it is used by the harvest system.


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Headmaster

Remote Condenser

Liquid Line

HarvestBypass


LiquidCheck Valve

Receiver



Hot GasValve

Inlet WaterValve

Water Pump

Purge Valve


Discharge Line

Discharge Line

SuctionLine

Compressor

LiquidLine

Evaporators

SuctionManifold

Harvest Cycle

During harvest the hot gas valve opens and hot gas flows into the side port of the refrigerantdistributor and then to the evaporator inlets. When the bin has been filled, and the machineis shutting down, rather than use a complex pump down system, the cuber simply startsa short freeze cycle and then shuts off. This moves almost all refrigerant to the receiverfor storage and returns oil to the compressor.

Another feature that enhances reliability is the continuous operation monitor. If the machinehas been in operation continuously for more than 15 cycles, the controller extends the nextharvest cycle a bit to rebalance the system. After that it returns to normal operation.


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Component’s Name Component’s Function

Purge Valve Opens to drain the reservoir at the beginning of theharvest cycle.

Inlet Water Valve Opens to fill the reservoir.

Liquid Line Check Valve Open during freeze, it closes when harvest begins toprevent refrigerant from flowing to the condenser.

Discharge Line Check Valve Typically open, it closes during the harvest cycle andthe off cycle to prevent refrigerant from flowing backinto the compressor.

Harvest By-Pass Solenoid Valve Normally closed, it opens for a few seconds at thebeginning of harvest to inject condenser refrigerantinto the hot gas harvest circuit.

Hot Gas Valve Normally closed, it opens during harvest to warm theevaporators.

Refrigerant Distributor Directs liquid refrigerant flow to the evaporatorsduring freeze and hot refrigerant gas to theevaporators during harvest.

Headmaster Usually not in the refrigeration circuit, but blocks liquidflow out of the condenser when discharge pressurefalls below a minimum point.

System Controller Controls the ice machine’s operation; accepts inputdata from several sensors and switches various loadson and off to make and harvest ice. Also controls thecontinuous operation monitor.

Bin Thermostat Signals to the controller when to switch ice making onand off.

Ice Sensors Signals to the controller when ice is being harvested.

Water Level Sensor Signals to the controller the water level in thereservoir.

Water Temperature Sensor Signals to the controller the temperature of the waterbeing pumped.

Discharge Temperature Sensor Signals to the controller the discharge linetemperature.

Component Description


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Purge Valve

Check Valve

Harvest Bypass Valve

The purge valve, located just above thewater reservoir, controls the draining ofwater from the reservoir.

When it is open and the water pump is on,water flows through this valve to the icemachine’s drain.

Regular draining of the reservoir dilutes theamount of mineral scale in the reservoir’swater, and that reduces the impact ofmineral-laden water supplies on theoperation of the ice machine.

The amount of water purged is adjustableto accommodate local water conditions.

The harvest bypass valve is only open fora few seconds each harvest cycle. Thepurpose of this valve is to add only thenecessary amount of refrigerant to theharvest circuit to promote a good release ofice.

There are two check valves , a liquid linecheck valve and a discharge line checkvalve.

During the off cycle, the liquid line checkvalve prevents refrigerant migration to theremote condenser from the receiver.

During the harvest cycle, the discharge linecheck valve separates the refrigerant in thecondenser from the refrigerant in theharvest circuit.

Key Components


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Overall Installation

1. Select a good location for the condenser, line set and ice machine. Select the minimumlength of precharged line set that will fit the application. Follow the recommendations inthe manual supplied with the machine.

2. Follow all applicable building codes.

3. For roof-mounts, have a roofing contractor install and attach the condenser to the roof.

4. Have the roofing contractor also cut a properly sized hole in the roof. A separate holemay be required for the electrical power supply.

5. Route the prechargedlines between the icemachine and the remotecondenser.

6. Either coil up the excesstubing OR cut out theexcess tubing.

7. Have a roofing contractorseal the hole(s)

8. Plan to and connectelectrical power to the icemachine 4 hours beforestarting up the machine.

9. Open the liquid line shutoff valve just prior to initialstart up.

10. At initial start up, followthe directions in the manualsupplied with the icemachine.

Remote Condenser

Excess Line SetCoiled Up

Ice Machine

Typical Installation

Remote System Installation


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Couplings:1. Remove the protector caps and plugs.Wipe the seats and threaded surfaces witha clean cloth.

2. Thoroughly lubricate the threads, o-rings,diaphragms and all internal couplingsurfaces with polyol ester refrigerant oil.

3. Position the pre-charged line couplingson the proper fittings of the ice machine andremote condenser.

4. Begin to tighten the couplings togetherby hand. Continue to turn the swivel nuts byhand until it is certain that the threads areproperly engaged.

5. Using two wrenches, one to rotate theswivel nut and one to hold the tubing inplace, tighten each coupling.

The diaphragms in the couplingsare pierced as the swivel nut isturned. During the piercing it’snormal for the swivel nut tobecome hard to turn.

Continue to tighten the couplingsuntil it requires much more forceto turn the nut, at that time nothreads should be visible.

6. Mark the position of the swivel nut relativeto the cabinet.

7. Rotate the swivel nut one quarter turnmore to completely seal the connection.

Clean and Lubricate Couplings.

Rotate Swivel Nut ¼ Turn More

Tighten Swivel Nut

Remote System Installation


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All lights blink once when power is re-suppliedto a system controller that has been switchedOff and disconnected from a power supply.

Pushing and releasing the Freeze buttonstarts the machine.

If there is a power interruption, the freeze lightwill be blinking as the machine goes througha restart sequence. After a short freeze cycleand complete harvest, the unit will resumenormal operation.

Beginning Freeze

Water enters the machine at initial start up andat the beginning of every freeze cycle to topoff the water reservoir.

The Freeze cycle light will be On, and thecompressor, water pump and fan motor willalso be working.

Freeze Cycle

Early in the freeze cycle the controlleractivates an anti-slush cycle, during which thewater pump stops for a short time and thenrestarts. This coats the evaporators with a thinlayer of ice, preventing slush and improvingwater flow characteristics over the freezingsurfaces.

The water reservoir will also be refilled onetime about ½ way through the freeze cycle.

Initial Start


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At the beginning of the harvest cycle, thewater pump is off, the purge valve is open, butbecause the pump is off no water drains. Afteran amount of time determined by the purgesetting, the pump restarts. After being openfor 74 seconds, the purge valve closes.

The inlet water valve then opens and waterflows in for a short time to supply water thatwill be used to assist harvest.

Harvest Cycle

Harvest continues until the controllerdetermines that enough time has elapsed torelease all the ice.

It does this by timing how long it takes fromthe beginning of harvest until the last cube hasfallen through the ice sensor’s “light curtain”.

Shut-Down

When the bin thermostat is covered with ice, itcloses its contacts, signaling the systemcontroller that no more ice is needed. At theend of the next cycle, the ice machine goesthrough a short freeze cycle before shuttingoff.

It will not restart for 4 minutes even if thethermostat is immediately warmed up. The BinFull light will be on during that time.

Beginning Harvest


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Cleaning begins with a push of the Harvestbutton to release any ice. After placing the icesensors in the reservoir, push the Cleanbutton and pour 24 ounces of Scotsman IceMachine Cleaner into the reservoir. After 10minutes push the Clean button again to startthe rinsing process.

After 20 minutes, push the Off button to stopthe machine. Put the ice sensors back in placeand push the Freeze button to restart themachine.

Diagnostic Lights

The controller has two diagnostic lights thatprovide a technician guidance towards thecause of possible operational problems.

The water light will blink if water flow into themachine is too slow or non-existent. Therefrigeration light will blink if no ice isharvested or the freeze cycle is too long.

There are differing blink rates for variousissues. See publication 291-809 for details.

Adjusting Water Purge

The amount of water purge is adjustable. Todo so, push and hold the Off button until themachine stops. Then push and hold the Offbutton again until the green lights glow.

The number of green lights glowing indicatesthe level of purge. To change the level ofpurge, push and release the Freeze button.Each push adjusts the purge one level higher.

When done, Push and release the Off button.

pub # 291-810

Cleaning


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