Work Vehicle Entropy

Have you ever noticed that the more you're required to speed up to get all your work done in a day, the more the cleanliness of your work vehicle suffers?

Some techs won't clean their vans, no matter how slow or busy the schedule gets, but most of us prefer a clean and organized vehicle. However, our van cleanliness can slip a bit in the really busy season.

This is entropy at work.

One way to think of entropy is the tendency for energy to be “wasted” or for energy to become more disorganized as it is changed from one form to another. In practical terms, the higher the entropy, the greater the waste in moving energy around. The lower the entropy, the less energy is wasted or unusable.

When your van is clean, you waste less energy trying to find what you need, but that is easier to do when you aren't “rushed.”

Don't confuse entropy with enthalpy. Entropy is the measure of the “availability” of energy to do useful work; enthalpy is a measure of total heat content.

Alternatively, you can think of entropy as the tendency for everything to go from more organized to less organized over time.

When we talk about entropy in classroom settings, we typically do it when analyzing a pressure-enthalpy diagram of a refrigeration circuit like the one shown above. You will notice the red shape is nearly a rectangle, barring the slanted line on the right; that line shows what happens when the refrigerant is compressed. Rather than going straight up and down, it curves to the right to show that additional heat is added to the refrigerant (enthalpy) as it is compressed. This increase in enthalpy follows something called lines of constant entropy; in other words, as more energy is added to a system, the faster the molecules move and the less organized they become.

As pressure and temperature increase, so (generally) does entropy. When it gets hot and the dispatcher starts putting pressure on you, your van entropy also increases.

In a refrigeration circuit, the system will work more efficiently when we achieve the desired movement of BTUs with a minimal amount of entropy. Practically speaking, this means using lower pressures and temperatures to move heat from one place to another when possible, but we still need to get the job of moving heat from one place to another done. In that process, entropy WILL occur.

We all know the guy who has the PERFECT van, the spotless tools, and the clean uniform. His van stays that way because he hardly does anything, and then he takes 20 minutes after every call wiping down and oiling his tools. He has very little entropy in his van because there is very little WORK being done.

Absolute zero is the temperature at which no molecular motion exists. In that state, there is also no entropy. No heat, no work, no disorganization. More heat, more work, more disorganization (entropy).

So, don't use me as an excuse for a messy van, but if your boss hassles you too much on a busy day, you can remind him of what we discussed today. Heat and pressure result in entropy, and the back of that van—that's entropy, baby.


P.S. – For those of you engineering types, I know that this article took some liberty with definitions. It's an analogy, not a doctoral physics thesis. You can find another explanation of entropy HERE and see if it's to your liking.

Related Tech Tips

Revisiting the Bull in a China Shop: Oversized Equipment
This article is an updated version of another HVAC School article on oversized equipment. This edition is a joint effort by Genry Garcia of Comfort Dynamics, Inc. and Kaleb Saleeby. Both of them are regular contributors to HVAC School, and we are grateful for their contributions. Thanks, guys! The symptoms and consequences of oversized heating […]
Read more
Hyperion Troubleshooting
This article was written by my good buddy, Bill Frisbie. Bill is a service manager and crack technician at AirFx, a Trane dealer in lovely Inverness, Florida. Thanks, Bill! One of the most intimidating things in the field is to walk up to a piece of equipment that you have either never worked on or […]
Read more
8 Tips for New Techs (So You Don't Get Fired)
If you are new to the trade, I'd like to welcome you. If you are young and new to the trade, we need you. We are grateful to have you. However, if you aren't thoughtful, you might get fired. No offense, millennials often just have a different way of looking at work than their Gen […]
Read more

One response to “Work Vehicle Entropy”

  1. Brilliant article and concept! It takes less energy to keep your work vehicle clean and tidy than to try and find what you’re looking for on the job if left disorganized. That’s entropy baby!

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.


To continue you need to agree to our terms.

The HVAC School site, podcast and daily tech tips
Made possible by Generous support from