Articles by John Tomczyk

The Professor: Explaining the R-22 Phaseout

August 3, 2009
With so much talk these days about HCFC-22, I thought I’d offer a back-to-basics look at this refrigerant that has been so popular for so long - but now is facing phaseout.
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The Professor: Comparing HFC-134a to R- 12

July 6, 2009
HFC-134a is the alternative refrigerant of choice to replace CFC-12 in many medium- and high-temperature stationary refrigeration and air conditioning applications. However, R-134a is not a direct drop-in refrigerant for R-12. Retrofit guidelines must be followed carefully when converting a system from R-12 to R-134a.
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The Professor: Replacement Blend HFC-410A

June 1, 2009
This article is the first in a series focusing on refrigerants and refrigerant blends. This month’s article will concentrate on the HCFC-22 air conditioning replacement refrigerant blend HFC-410A, better known as R-410A.
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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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Michael Willburn, president, Infloor Heating Systems, joins the program to discuss his company, radiant heating, industry trends, and whether contractors are becoming more interested in radiant heating. Posted on July 11.

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