Most HVAC writing online is either a sales pitch or a repeat of a number nobody can trace. These posts cite the study, name the authors, and link the document. Where good data doesn't exist, we say so instead of inventing it.
Every threshold that makes sense on comfort cooling is wrong on refrigeration. A freezer running perfectly sits 56 degrees below the line that means an iced coil on an AC — which is why generic monitoring puts refrigeration in permanent alarm.
Read itR-448A and R-449A do not boil at one temperature. They boil across about ten degrees — which is larger than most of the deviation bands anyone judges a system on. Read the wrong end of that range and the error swamps the signal.
Read itThermal mass is the enemy of early warning. By the time a box thermometer moves far enough to trigger an alarm, the refrigeration system has been failing for hours and the product has been warming for most of them.
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