Articles by John Tomczyk

The Professor: Defrost Termination/Fan Delay Controls

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

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

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

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

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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2014 World Energy Engineering Congress

Scenes from the 2014 World Energy Engineering Congress in Washington, D.C.


NEWSMakers: Jim Johnson

Jim Johnson,an experienced trade school and community college instructor, discusses the HVAC industry and his column in The NEWS, ‘The Service Ticket.’ Listen now for a hint to the Not Enough Heat question from the Dec. 15 issue. Posted Jan. 30.

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2015 January 26

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Regional Standards

With regional standards for a/c equipment going into effect in 2015, how do you think it will impact the industry?
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2015 National Plumbing & HVAC Estimator

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

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