Articles by John Tomczyk

The Professor: Digital Capacity Control for Compressors

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

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

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

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

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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The Professor: Diagnosing Air Conditioning Systems

This is the second of three columns on systematic air conditioning troubleshooting and diagnostics. The first appeared in the May 5 issue of The NEWS. The third part will appear in the July 7 issue. This article deals with modern evaporator and condenser designs to meet the new minimum 13 SEER requirements.
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The Professor: Diagnosing Air Conditioning Systems

This is the first of three columns on systematic air conditioning troubleshooting and diagnostics. It will deal with airside and the evaporator. In a/c system diagnostics, a service technician must realize that system problems fall mainly under two major categories: airside problems and refrigerant cycle problems.
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The Professor: Troubleshooting With Voltmeter

It is of utmost importance for service technicians to understand voltage troubleshooting when servicing HVAC and refrigeration equipment. The majority of service problems are electrical problems, which usually cause mechanical problems. This article illustrates how to voltage troubleshoot using a voltmeter.
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The Professor: Restricted Metering Device

This column explores how a restricted metering device will affect system performance and efficiency. The system is a commercial refrigeration system employing a receiver and a thermostatic expansion valve (TXV) as the metering device. The refrigerant is R-134a.
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The Professor: Refrigerant Undercharge

My Jan. 14 column in The NEWS focused on system overcharges. This column will look at an undercharge of refrigerant. In the example to be used, we will look at a medium-temperature refrigeration system running on HFC-134a and having a thermal expansion valve (TXV) and liquid receiver.
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2014 Energy Efficiency Forum

Highlights from the 25th annual Energy Efficiency Forum in Washington, D.C.


NEWSMakers: Jason Vogelbaugh

Jason Vogelbaugh of Alpha Controls drops in to the NEWSMakers podcast to discuss his role with the company, the InsideIQ Building Automation Alliance, and current energy-efficiency projects being worked on. Posted on Sept. 26.

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NEWS 09-29-14 cover

2014 September 29

Check out the weekly edition of The NEWS today!

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DOE has denied AHRI’s petition for reconsideration of walk-in standards. Is it getting harder to reach consensus on efficiency standards?
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2014 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

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