1. Student CD for Commercial Refrigeration for A/C Technicians Chapter 12 Ice Machines

2. Copyright 2006 Thomson Delmar Learning 2 Learning Objectives Ice machine types and applications Basic ice machine operation Installation-related service Ice machine maintenance and cleaning Ice machine warranties Troubleshooting ice machines

3. Copyright 2006 Thomson Delmar Learning 3 Commercial Ice Commercial cube ice is pure ice –Impurities like minerals, chlorine, air, and odors are eliminated –Only the remaining pure water is frozen into cubes

4. Copyright 2006 Thomson Delmar Learning 4 Courtesy of Manitowoc Ice Only pure water freezes on the evaporator Minerals collect in the sump tray and are flushed out during the harvest cycle Manitowoc Cube Ice Machine

5. Copyright 2006 Thomson Delmar Learning 5 Manitowoc Freeze Cycle Following is the basic ice making sequence of a Manitowoc ice machine: –Mineral laden water from the last batch of ice is flushed from the system –Fresh water fills the sump trough –Refrigeration makes the evaporator cold –Water turns to ice as it flows over the evaporator

6. Copyright 2006 Thomson Delmar Learning 6 Basic Components of a Manitowoc Ice Machine TEV Evaporator Thickness probe Sump Trough Dump Valve Hot Gas Valve Water supply Pump

7. Copyright 2006 Thomson Delmar Learning 7 Manitowoc Ice Making Cycle Compressor Starts Evaporator Cools Pump Out Stops After 45 Seconds 5” 16 Thickness probe SUMP TROUGH DUMP VALVE

8. Copyright 2006 Thomson Delmar Learning 8 Manitowoc Ice Making Cycle After 30 Seconds water Pump Starts Ice Builds On Evaporator When Ice Bridge is 1/8" thick... water closes circuit on thickness probe

9. Copyright 2006 Thomson Delmar Learning 9 Manitowoc Harvest Cycle When the ice is fully formed the harvest is initiated Hot gas warms the evaporator and releases the slab of ice After the ice drops the next freeze cycle begins

10. Copyright 2006 Thomson Delmar Learning 10 Manitowoc Harvest Cycle Pump Out During Harvest Hot Gas Valve Opens Evaporator Warms, Ice Falls Off Evaporator When the ice slab drops off the evaporator it forces the curtain open.

11. Copyright 2006 Thomson Delmar Learning 11 Manitowoc Harvest Cycle Hot Gas Valve Closes Pump Out Stops Freeze Cycle Restarts Ice making resumes… After the ice drops, the curtain closes. This ends the harvest cycle and initiates the next freeze cycle.

12. Copyright 2006 Thomson Delmar Learning 12 Ice Harvest Following are pictures showing the end of the freeze cycle and the ice harvest.

13. Copyright 2006 Thomson Delmar Learning 13 Note: the water curtain has been removed for illustration purposes Courtesy of Manitowoc Ice When the ice is fully formed on the evaporator…... the thickness probe activates the harvest cycle Ice Harvest

14. Copyright 2006 Thomson Delmar Learning 14 Courtesy of Manitowoc Ice The hot gas defrost releases the ice from the evaporator Ice Harvest The slab of ice drops into the bin

15. Copyright 2006 Thomson Delmar Learning 15 Ice Harvest If the bin is full, the door remains open. If the door switch remains open for more than 7 seconds, the ice machine shuts off on “full bin.” Courtesy of Manitowoc Ice

16. Copyright 2006 Thomson Delmar Learning 16 Flake Ice Flake ice facts: –Melts faster than cubes –Ice contains water-borne impurities –Used in salad bars and for icing down fish –Only 10% of ice machines are flakers Flake ice production: –Ice is formed on the sides of a tubular evaporator –A motor driven auger scrapes off the ice –The flakes of ice drop down a chute, into the ice storage bin

17. Copyright 2006 Thomson Delmar Learning 17 Courtesy of Manitowoc Ice Motor Gearbox Coupling Bottom seal Water drain Evaporator tubing AUGERAUGER Ice chute Water valve ICECHUTEICECHUTE Compressor Control Box Courtesy of Manitowoc Ice Manitowoc Flaker

18. Copyright 2006 Thomson Delmar Learning 18 Installing an Ice Machine Location –Need air circulation and service access Drains –Proper size and slope –All drains should be run separately Proper inlet water line size Proper water pressure –Usually 20 psi minimum and 80 psi maximum

19. Copyright 2006 Thomson Delmar Learning 19 I/M Installation drawing 1” air gap above floor drain Run drains separately Vent drains Dump valve drain Bin drain Water cooled condenser drain Courtesy of Manitowoc Ice

20. Copyright 2006 Thomson Delmar Learning 20 Remote Condenser Piping Use factory tubing kits Coil excess tubing properly or cut it out: –Coil like a corkscrew (for proper oil return) –Never coil in loops (see pictures) –Best to cut out excess tubing before connecting: Cut out excess piping Braze together with couplings Evacuate tubing set only Connect to units –Note: tubing sets only have vapor –The full charge is in the head or condensing unit

21. Copyright 2006 Thomson Delmar Learning 21 Courtesy of Manitowoc Ice Manitowoc remote condenser Improper installation with excess tubing Excess tubing should be cut out before installation

22. Copyright 2006 Thomson Delmar Learning 22 Ice Machine Maintenance Follow factory cleaning instructions –Cleaners remove scale buildup –Sanitizers prevent bacteria growth Water filters can help reduce the need for cleaning Keep the air cooled condenser clean –Most ice machines have an air filter

23. Copyright 2006 Thomson Delmar Learning 23 Ice Machine Condenser Filter

24. Copyright 2006 Thomson Delmar Learning 24 Water-cooled Condenser Maintenance Measure the water temperature leaving the condenser. It should be between 95° and 105°. If higher than 105°, adjust the valve to lower it If lower than 95°, check head pressure: –If the head pressure is low, adjust the water valve to raise it. –If head pressure is correct, the condenser probably has a small scale buildup. Clean it. –If the head pressure is high, the condenser probably has a severe scale buildup. The condenser may need to be replaced.

25. Copyright 2006 Thomson Delmar Learning 25 Common Ice Machine Warranties 3 year parts and labor warranty on everything Additional 2 years parts-only warranty on the compressor Five year parts and labor warranty on the evaporator Note: warranty work must be performed by factory authorized technicians

26. Copyright 2006 Thomson Delmar Learning 26 General Troubleshooting of Ice Machines 50% to 75% of ice machines problems are water related: –Dirty water circuit –Water pressure –Drain problems Leave refrigeration gauges in the truck –If absolutely necessary, use close-coupled gauges

27. Copyright 2006 Thomson Delmar Learning 27 Close-coupled gauges used on ice machines

28. Copyright 2006 Thomson Delmar Learning 28 “No Ice” Service Call Usually a major component problem –Water or power failure –Safety control Note: most current ice machines have diagnostic circuit boards which stop the machine and indicate what the problem is.

29. Copyright 2006 Thomson Delmar Learning 29 “Not Enough Ice” or “Slow Ice” First, take a capacity check: 1.Determine water and ambient temperatures 2.Determine the total cycle time (freeze + harvest) 3.Determine the weight of the batch of ice 4.Calculate the production = [1440 minutes  Cycle time] x Weight of ice Note: if production is within 10% of the factory rating it is considered to be operating properly. Check drains to make sure water is not backing up into the storage bin.

30. Copyright 2006 Thomson Delmar Learning 30 Additional Troubleshooting Tips Check the formation of the ice cubes –Too large or too thin may requires adjustment –“Burned” cubes may require evaporator cleaning Water cooled regulating valve leaking –This will cause improper harvests –Also wastes water when machine is off Bin drains may sweat in hot humid locations

31. Copyright 2006 Thomson Delmar Learning 31