Articles by John Tomczyk

The Professor: Restricted Airflow Over an Evaporator

May 11, 2009
There are a number of ways that the airflow over an evaporator can become restricted. Anytime the evaporator coil sees reduced airflow across its face, there will be a reduced heat load on the coil. No airflow will cause a lot of the refrigerant in the coil to remain a liquid and not vaporize.
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The Professor: Defrost Termination/Fan Delay Controls

April 6, 2009
The defrost termination/fan delay control is a temperature-activated, single pole-double throw switch controlled with a remote sensing bulb. The control can be an adjustable type. One example of the installation of an adjustable defrost termination/fan delay control is on a walk-in freezer’s evaporator.
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The Professor: Compressor Amperage Curves

February 2, 2009
Compressor performance curves are available from the compressor manufacturer for each of their compressors. Compressor data comes in either graph or table type. This article will take a closer look at the table type data and concentrate on the current (amps) performance data.
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The Professor: Condenser Efficiency Affects the System

January 12, 2009
One of the main components of any refrigeration or air conditioning system is the condenser. As its name implies, one of the main functions of the condenser is to condense the refrigerant sent to it from the compressor. However, the condenser also has other functions.
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The Professor: Scroll Compressor Internal Protection

December 1, 2008
Many modern day scroll compressors incorporate a variety of internal safety controls that can actuate the internal line break motor protection. Some safety features that can be found in the air conditioning scroll less than seven tons are described here.
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The Professor: Digital Capacity Control for Compressors

November 3, 2008
Compressor capacity control is desirable for optimum system performance when loads vary over a wide range. Compressor capacity control through modulation can reduce power consumption, produce better dehumidification control, and reduce compressor cycling along with smaller compressor starting currents.
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The Professor: The Scroll Compressor

October 6, 2008
This is the second of three columns covering the scroll compressor. This article covers the scroll compressor’s advantages and the modulating scroll compressor. The third article will cover digital capacity control for scroll compressors and scroll compressor protection.
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The Professor: The Scroll Compressor - A History

September 1, 2008
This is the first in a series of three articles covering the scroll compressor. This first article covers the history of the scroll compressor along with the scroll compressor operation.
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The Professor: Air Conditioning System Troubleshooting

August 4, 2008
This is the final article in a series covering inefficient compressors, noncondensibles in the system, low and high condenser entering air temperatures, and different metering devices as they apply to troubleshooting air conditioning systems.
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The Professor: Systematic Troubleshooting

July 7, 2008
This is the third in a series of columns on systematic air conditioning troubleshooting and diagnostics. This column deals with liquid subcooling, liquid and suction line restrictions, overcharges, and undercharges.
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