Fancy Refrigerant Words
There are all sorts of complicated refrigerant acronyms.. HFC, HCFC, CFC and well as the mythical Zeotropic, Azeotropic and near Azeotropic… Let’s simplify
CFC = Refrigerant that is really bad for the Ozone. They are almost all gone. R-12 and R-11 are examples
HCFC – Refrigerants that are bad for the Ozone but not as bad as CFCs. Most common is R22.
HFC – Refrigerants that aren’t bad for the Ozone but they do add to global warming through the greenhouse effect. Most common is R410a.
When it comes to the whole zeotropic, azeotropic thing the main thing you need to know is that older refrigerants were often just one type of molecule. That meant that they condensed and evaporated consistently and it didn’t matter if you added them to the system via vapor or liquid. These simple refrigerants were known as PURE refrigerants.
Today we mostly work with HFC and HCFC blends. These blends can be Azeotropic, which means they blend together and act as one refrigerant or Zeotropic which means they have “glide” resulting in different boiling and condensing temperatures of the refrigerants mixed in. Rubber meets the road in a refrigerant with high glide when you need a separate “condensing” and “boiling” termperatures on the PT chart. R407C is an example of a high glide zeotropic refrigerant where R410a has nearly 0 glide. While R410a is TECHNICALLY zeotropic is is so close to being Azeotropic that the industry coined the phrase near-azeotropic.
In all blends, you must charge the refrigerant as a liquid to prevent the refrigerants from separating in the vapor state. As always, when charging liquid in the suction line, add it slowly and carefully, allowing all the liquid to boil off before entering the compressor to prevent flooding/slugging.
Bryan Orr is a lifelong learner, proud technician and advocate for the HVAC/R Trade