Zeotropic blends are mixes of refrigerants with different boiling points, so at one pressure they start boiling at the bubble point and finish at a higher dew point. R-407C glides about 10 degrees F, while near-azeotropes such as R-410A glide too little to matter. Techs use dew point values for superheat and bubble point values for subcooling, and charge blends as liquid so the mix stays correct.
It's 407C, so use the dew column for superheat, the glide will throw you off by ten degrees if you don't.
Charge zeotropic blends as liquid, throttled into the suction side, or the mix left in the cylinder drifts off spec.
Also heard as
- temperature glide
- zeotropic glide
Related terms
Saturation
The state where liquid and vapor refrigerant coexist, so its temperature is locked to its pressure.
PT chart
Pressure-temperature chart: a table giving each refrigerant's saturation temperature at each pressure.
Refrigerant
The working fluid that carries heat around a refrigeration or air conditioning system by boiling and condensing.
Weigh in
To charge a system with a measured weight of refrigerant on a scale, set by nameplate charge and line set length.