Monthly Archives: March 2013

You can be surprised by anyone at any time when you least expect it, but you can always gain something from the experience. 

For more than fifteen years I’ve been doing troubleshooting contests for HVACR magazines. As a part of those contests, individuals who make the correct diagnosis of the problem presented have an opportunity to win a prize if their name is chosen in a drawing. In some cases, the prizes are provided by sponsors. In one particular situation, the sponsor wasn’t able to provide the listed prize, and, after several emails back and forth over an extended period of time with the individual who was waiting for his prize, I got a message that said…”Is this just for publicity or what?”

Uh….what? It was the first time I had ever been accused of lying to someone in print. I was surprised. Then, I remembered a fundamental philosophy, so I was able to gain something from the experience.

 I remembered that if someone accuses you of something despicable or is suspicious that you might cheat them in some way, then you have just learned something about that person…if they had the opportunity to do something despicable or cheat someone else in some way, they would do it. It’s a simple philosophy, really. If a person thinks of others from a negative perspective, it clearly illustrates that they are capable of doing the same thing. If they weren’t, they wouldn’t think of such a thing in the first place.

So, even though I could have been insulted by a totally unwarranted, outrageous accusation, I went ahead and figured out a way to solve the situation. And, when I sent this person his prize, I made sure that receipt of the package would require a signature, because… well, because I had learned something about this person. And knowing the character of anyone you’re dealing with is valuable. It helps you to make the right decisions about what to do in any given situation.

Learn From Yesterday….Live For Today…..Look Forward To Tomorrow




HVAC technicians in training are often intimidated when they see a psychrometric chart for the first time since there are six separate sets of lines that are used to plot conditions once temperatures in a given situation are established. However, the chart can be demystified by reviewing the sets of lines individually in skeletal illustrations.

In Figure One below, are the dry bulb temperature lines of a psychrometric chart.


Figure One

Figure One

These lines are properly referred to as Constant Dry Bulb Temperature Lines because any point on any given line has the temperature listed on the scale.

The lines shown below in Figure Two, are also constant temperature lines, and they are identified as Wet Bulb Lines.


Figure Two

Figure Two


These lines run down from the temperature scale on the curved section of the chart at an angle of approximately 30-degrees off of horizontal.

The next set of lines shown in Figure Three are the Constant Relative Humidity Lines.


Figure Three

Figure Three


The top curved line on the chart shown as the 100% relative humidity line is also known as the saturation line, meaning that we no longer have water vapor in the air, but liquid condensing from it. In most situations, many people are comfortable when the humidity level is around 50%. It is usually recommended that the humidity level in a building remain between 40% and 60%.

These first three sets of lines are the basic ones that allow a technician to take both a wet bulb and dry bulb measurement in a given area, and then plot the relative humidity conditions in the space.

In Part Two, we’ll look at three more sets of lines on the psychrometric chart.

Learn from yesterday…Live for today…Look forward to tomorrow










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