Articles by John Tomczyk

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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The Professor: Bad Compressor Valves

November 7, 2011
Many servicemen experience service calls where the compressor has both a low head pressure and a high suction pressure. There are three main reasons why a compressor will simultaneously have a low head pressure and a high suction pressure.


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The Professor: Systematic Troubleshooting of a Restricted Liquid Line

October 3, 2011
The problem in this scenario is a restricted liquid line after the receiver. Where do you go from here?


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The Professor: Chemical-Free Cooling Tower Treatment

September 5, 2011
When evaporation occurs in a cooling tower, only the water evaporates; it exits the cooling tower as water vapor, but leaves the minerals behind to concentrate in the cooling tower’s water system.
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The Professor: Loss of Air Conditioning Cooling

August 1, 2011
For this column I want to discuss a real life situation regarding poor cooling in a residence and reduced airflow coming from the registers in the house. The air conditioner is a three ton (36,000 btuh), HCFC-22, split type, air conditioner with the A-coil in the plenum of the furnace located in the basement.
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The Professor: Basics of Condensers and Coils

July 4, 2011
The condenser is the component that rejects the heat from the system. Most equipment is air cooled and rejects heat to the air. The coils are copper or aluminum and both types have aluminum fins to add to the heat exchange surface area.
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The Professor: Going Chlorine-Free in Retrofits

June 6, 2011
Ferris State University’s Commercial Refrigeration Laboratory has gone totally chlorine-free. By replacing the refrigerant HCFC-22 that was in two medium-temperature commercial refrigeration cases in the laboratory, the students in the associate degree program in HVACR can boast that the lab is now chlorine-free.
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The Professor: Condenser Splitting

May 2, 2011
This column focuses on condenser splitting. But first, here’s a quick review of condenser flooding before covering condenser splitting to help all better understand both concepts and their advantages and disadvantages.
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Mini Split Installation

Twin Cities contractor Aabott Ferraro helped retrofit an older St. Paul home.

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NEWSMakers: Doug Dougherty

Doug Dougherty, president and CEO of the Geothermal Exchange Organization (GEO) joins the program to discuss the latest happenings with GEO, including the drive to get included in state and federal definitions of renewable energy, plus the future of geothermal.  Posted on July 25.

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