Articles by John Tomczyk

The Professor: Oil Safety Controllers and Their Circuits

Oil safety controllers often come in two types: bellows (mechanical) and transducer (electronic). Bellows-type controllers sense crankcase pressure and oil pump discharge pressure, usually through some type of tubing, and then transmit the pressure to flexible bellows. Transducer-type controllers use a pressure transducer.
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The Professor: Net Oil Pressure

Many larger compressors in the refrigeration and air conditioning field have forced-oiling systems. These compressors are usually over 5 hp. They contain an oil pump located at the end of the compressor’s crankshaft. The crankshaft is actually connected to the oil pump and supplies power, which turns the oil pump.
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The Professor: Systematic Troubleshooting

The problem we are going to deal with here pertains to a restricted liquid line after the receiver. Provided is a service checklist. Assume that the refrigeration system is a TXV/receiver system, employing a filter drier and sight-glass. The system has R-134a as the working refrigerant.
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The Professor: Retrofit R-438A

There is an estimated 900 million pounds of HCFC-22 installed in refrigeration and air conditioning systems in the United States. This article covers one of the leading refrigerant blend candidates for retrofitting R-22 systems for both a/c and refrigeration applications.
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The Professor: Variable-Frequency Drives

The HVACR industry is one where both centrifugal pumps and fans are used on an ongoing basis. Because of this, HVACR systems are huge energy consumers. Creating higher-efficiency systems offers a tremendous opportunity for great electrical and monetary savings. Many of these savings can be achieved through the use of variable-frequency drives.
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The Professor: Retrofitting R-22 Systems

As mentioned earlier, most new systems will be manufactured with R-410A. However, the question of what is the best retrofit refrigerant blend for existing R-22 systems is often asked by technicians and equipment owners. There is no one quick-fix solution or answer to this question. The answer depends on several key factors.
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The Professor: Explaining the R-22 Phaseout

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

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

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

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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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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NEWS 01-26-15 cover

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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