We all have been read or been told to use some magic number like 80% of the old charge when retrofitting to a new refrigerant, but is that going to get you where you need to be? How can one number be valid for all the refrigerants that are now available and those they’re replacing? Sounds like a “Rule of Thumb” to me.
To get a much closer weight of the new refrigerant, you need to compare their liquid density. By using density you can calculate what the equivalent liquid volume of the new refrigerant liquid will be…and that will be a much better guarantee you’ll get it right.
Here is a chart listing various refrigerant densities and a simple formula to use to calculate the new weight needed:
Often when servicing an HVACR system the technician finds a situation where the compressor’s apparent performance is questionable. Any number of possible scenarios and causes may lead to this such as a higher than expected suction pressure or possibly an excessive amp draw. In any case, after performing all the standard system checks and tests the question often becomes “Is the compressor doing what it’s designed to do?”
To get to this point the tech may believe he has exhaust all of his resources and feels stumped as to why this pump isn’t operating as he feels it should. There’s one additional tool he is overlooking. The Compressor Performance Curve.
(Click on the link below to read more…)
Using Performance Curves As A Service Tool