Articles by John Tomczyk

The Professor: Compressor Overheating

My column in the March 8 issue of The NEWS dealt mainly with reciprocating compressors experiencing low head pressure and high suction pressure from bad valves. This column takes an in-depth look at high compression ratios that cause compressor overheating along with high compressor discharge temperatures.
Read More

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.
Read More

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.
Read More

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.
Read More

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.
Read More

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.
Read More

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.
Read More

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.
Read More



Image Galleries

2014 World Energy Engineering Congress

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


NEWSMakers: Greenheck Mixed Flow Fan, Model EQB

Shane Dock, Application Engineer at Greenheck, will introduce you to Greenheck’s new EQB mixed flow fan. We’ll discuss what the features of the EQB’s innovative design, what kinds of applications can utilize the EQB, and why the EQB is an attractive inline choice for your customers’ projects.  Dock is currently focused on applications regarding inline fans, gravity ventilators, and electrical products. Posted March 4th.



More Podcasts


NEWS 03-02-15 cover

2015 March 2

Check out the weekly edition of The NEWS today!

Table Of Contents Subscribe

HVAC Trends

The NEWS regularly reports on HVAC industry trends in our weekly issues. What trends do you see?
View Results Poll Archive


2015 National Plumbing & HVAC Estimator

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

More Products

Clear Seas Research


Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.


Magazine image
Register today for complete access to Get full access to the latest features, Extra Edition, and more.


facebook icontwitter iconyoutube iconLinkedIn i con