Articles by John Tomczyk

The Professor: Systematic Troubleshooting an Oil-Logged Evaporator

August 6, 2012
Systematic troubleshooting using a system check sheet is still the best method for the conscientious service technician to pinpoint hard-to-find system problems. This article explores how evaporators can become oil logged, and includes symptoms with explanations of a system with an oil-logged evaporator.


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The Professor: Condensing Temperatures and Condensing Splits

July 2, 2012
The three functions of the condenser are desuperheating, condensation, and subcooling. Read to find out more about what the Professor has to say about these three topics. 


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The Professor: Hard Ice vs. Soft Ice

June 4, 2012
Homes, restaurants, and businesses rely on clear, clean ice for many applications. Ice is considered a food source, and the water that makes the ice must be of good quality; but what it is the difference between hard and soft ice? Read to find out. 


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The Professor: System Check Sheets

May 7, 2012
While my last series of columns explored liquid subcooling in a refrigeration system, this article will compare subcooling amounts in a refrigeration system incorporating an overcharge of refrigerant, a dirty condenser, and air in the system.


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The Professor: The Needed Amount of Condenser Subcooling

April 2, 2012
The amount of condenser subcooling needed is system dependent. The more pressure drops — friction and static — associated with the lines and accessories that carry the liquid in the system, the more need there will be for liquid subcooling to prevent liquid line flash gas.


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The Professor: Why Is Condenser Subcooling Needed?

March 5, 2012
Condenser subcooling ensures that there is a liquid seal at the condenser’s bottom so the liquid line or receiver will not be fed with vapors. This condition prevents any noncondensables, like refrigerant vapor or air, from leaving the condenser’s bottom and entering the receiver or liquid line.


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The Professor: The Importance of Liquid Subcooling

February 6, 2012
This is the first of a three-part series covering the importance of liquid subcooling in a refrigeration or air conditioning system.


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The Professor: Helical Oil Separators

January 9, 2012
Oil separators are essential on low and ultra-low temperature refrigeration systems and on large air conditioning systems up to 150 tons. Most compressor manufacturers require oil separators on all two-stage compressors.


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The Professor: Megohmmeters for Preventive Maintenance

December 5, 2011
Megohmmeters (meggers) are electrical meters used to check the resistance and condition of the motor windings and the condition of the refrigeration and oil environment around the motor windings. A megger is nothing but a giant ohmmeter that creates a very large dc voltage (usually 500 volts dc) from its internal battery.


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Geothermal Comes in More than One Flavor

November 21, 2011
Since the tax credit program became available, all types of geothermal options have been on the minds of the building community. The earth loop, often referred to as the refrigerant loop, may be installed in three different configurations: diagonal, vertical, and horizontal.


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