The gas laws… We all learned about them in school and promptly forgot all about them. I really think that we need to dig our books out, dust that information off, and work to understand and apply it.

Bob and Tim have arrived at a customer’s house that uses fuel oil for heat. This is a “no heat” call — the customer called first thing this morning and said that the oil furnace was not coming on, and the house was cold. When they arrived, they talked to the customer, and the customer said that he had made several tries to get the furnace to operate but with no luck.

It’s the middle of summer and your customer, who can’t provide you with any helpful information about the history of this situation since they just recently purchased the business, is complaining that the temperature inside their small convenience store won’t get comfortable whenever the outdoor temperature gets over 90°F.

Bob and Tim have responded to a service request where the customer is explaining that their heat pump is running all the time. The indicator light on their thermostat is lit most of the time, indicating the strip heat is on as well. The weather is cold today but has been warm some days and cold some days. It’s a very unusual heating season.

The first point to understand about refrigeration theory is that heat is energy, and it can be made to move. If enough heat is removed from a glass of water, the water will freeze to ice. When that heat is allowed to move back into the ice, the ice will melt.

Bob and Tim are on a service call on a really cold and blustery day. The temperature is 27°F, the wind is blowing, and it’s snowing and sleeting. When the customer called, she said that their home is getting cool inside, and their heat pump is running all the time with the temperature dropping inside the house. They arrived at the front door, talked to the homeowner, and decided to look around. They went to the closet where the indoor unit for the heat pump was located and determined that the heat pump itself was not running, only the fan and strip heat. 

In this troubleshooting problem, it’s the middle of July, and you are the follow-up technician on a callback. The original complaint was a “no cooling at all” call, and the technician who preceded you on this job (we’ll call him Technician #1) has only limited experience, but he reported correctly that he found a failed transformer and replaced it. 

Bob and Tim have had a big day at work — it’s 3:30 in the afternoon, and they are done for the day. They’re having coffee at a local restaurant, talking about their careers when Tim asked a question, “What is a ton of refrigeration, and why is it called a ton?”

Whether the commercial refrigeration equipment you’re working on is a small under-counter refrigerator, a keg refrigerator, a large walk-in freezer, or a transportation refrigeration system, many of the technical concerns will be the same.

Bob and Tim were on their way to a no heating call. When they arrived, they looked at the house and saw that it had a package unit. They talked to the housewife and she told them that the unit stopped running sometime in the middle of the night last night.