#refrigeration

When we say that there is “flash gas” at a particular point in the system, it can either be a bad thing or a good thing, depending on where it is occurring. Flash gas is just another term for boiling. It is perfectly normal (and required) that refrigerant “flashes” or begins boiling directly after the […]

One of my most popular YouTube videos goes over how to adjust TXV superheat. It's a very simple little video that I did at my desk, and the other day I got this comment: “Good Video but I hate to say this BUT, with the title SCHOOL, why would you show the public an instructional […]

Why Defrost? Let's start with the basics and move on from there. Defrost is necessary when the coil temperature drops below 32°F. Defrost can be as simple as turning the compressor off for a period of time or as elaborate as reversing the flow of refrigerant for the whole system or just parts of the […]

We have discussed DTD (design temperature difference) quite a bit for air conditioning applications, but what about refrigeration? Let's start by defining our terms again. Suction Saturation Temperature The saturation temperature is the temperature at which the refrigerant will be at a given pressure if it is currently changing state. This change of state would […]

This article was written by Jeremy Smith CM, an experienced refrigeration tech and all-around great dude. Thanks, Jeremy. A very common means of control seen on refrigeration equipment is the pump down control. Why do we use this rather than just cycling the compressor off and on like a residential HVAC unit? Since most refrigeration equipment […]

Let's take a deeper dive into the magic that is gas defrost. Most techs who are familiar with heat pumps understand the basics of a gas defrost. When we apply this strategy to a larger system where we're only reversing a small part of the system, we need to add some controls and valves to […]

  Illustration Courtesy of Emerson CO2 is a pretty nice refrigerant. It has zero ODP (ozone depletion potential) and a GWP (global warming potential) of 1. CO2  has been used as a refrigerant almost from the very beginning of refrigerants, and it's been making a big comeback in market refrigeration (especially in colder climates). CO2 […]

Do you know how a solenoid valve works? Really? On the surface, I think we all understand how a solenoid valve works. The coil energizes, creating an electromagnet. That temporary magnetism lifts an iron plunger within the valve allowing refrigerant to flow. But is it really that simple? It turns out that the answer isn't […]

Basic Compressor Functions The compressor's job is to circulate refrigerant through the system by means of vapor compression, similar to the way your heart moves blood through your circulatory system. Refrigerant circulation is measured in lbs/min or lbs/hour; this is called mass flow rate—the mass flow rate changes depending on the density of the refrigerant […]

Dick Wirz, author of Commercial Refrigeration for Air Conditioning Technicians, talks about making the switch from A/C to refrigeration. Dick Wirz is an advocate for using rules of thumb, which is a controversial position. However, rules of thumb are an excellent way for A/C techs to dip their toes into the refrigeration world. Rules of […]

In this episode of the HVAC School Podcast, Bryan talks with Jeremy Smith about refrigeration tips, terms and processes. They also cover the similarities and differences between A/C and refrigeration. Being on-call as an A/C tech is not all that different from being on-call as a refrigeration tech. Similarly, the principles of heat transfer don't […]