Articles by John Tomczyk

The Professor: A Recap on Oil Traps

Functions, Dealing with Oil Reservoirs

The function of an oil reservoir, commonly known as an oil trap, is to prevent large oil slugs from forming. This is accomplished by trapping a small amount of oil in the reservoir or trap and gradually returning it to the compressor.


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The Professor: Defining the Impact of Frosted Compressor Head

What Frost on a Compressor Head Is — and What it Isn’t

All frost means is the suction line or compressor is below freezing, and the moisture in the air has reached its dew point temperature and condensed. 


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The Professor: Oil Pumps and Net Oil Pressure

Understanding the Differences is Key for Successful Servicing

Often, compressors in the refrigeration and air conditioning fields have forced oiling systems. Here is a look at some of those oil pumps.


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The Professor: Don’t Forget About the Oil Check Valve

Dealing With Startup and System Problems

An overview of the oil check valve, which will only let oil pass from the compressor’s motor barrel to its crankcase.


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The Professor: Troubleshooting Using Compressor Discharge Temp

Checking Over an Often Overlooked Aspect of Servicing

The compressor’s discharge line temperature is important because it is an indication of the amount of heat absorbed in the evaporator and suction line and any heat of compression generated by the compression process.


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The Professor: Crankcase Heaters

Coping With Refrigerant Migration

Migration of refrigerant to the compressor’s crankcase during an off cycle is a serious problem, as significant compressor damage can occur if the problem is not remedied. 


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The Professor: Understanding, Avoiding Transformer Burnouts

Solving Low-Voltage Power-Consuming Faults

This column will try to explain the voltages associated with the high or wild leg coming from the secondary of a Delta service transformer. 


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The Professor: ‘Wye’ or ‘Star’ Configurations

A Look at Electrical Service Transformers

John Tomczyk discusses the Wye or Star configuration of the three-phase electrical service, which usually delivers four wires to the building.


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The Professor: Low Ambient Controls Reduce Head Pressure

Control Is a Style of Head-Pressure Control Valve

When refrigeration systems are exposed to low-ambient conditions, the condensing pressure (head pressure) will fall. If the head pressure gets too low, the metering device will not have enough pressure drop across it to operate properly.


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The Professor: TXV Dos and Don’ts

The Externally Equalized Thermostatic Expansion Valve

The thermostatic expansion valve (TXV or TEV) is a metering device located between the liquid line and the evaporator. 


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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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