Fast Checks for Refrigerant Charge?

May/June 2002
A version of this article appears in the May/June 2002 issue of Home Energy Magazine.
Click here to read more articles about Cooling & Air Conditioning
May 01, 2002
For A/C technicians, new options exist for testing refrigerant charge levels.
              Air conditioning systems that aren’t correctly charged don’t work as efficiently or for as long as they otherwise would.Yet incorrectly charged A/C systems are more common than correctly charged ones.Tests of more than 4,000 residential cooling systems in California revealed that about 34% were undercharged, 28% were overcharged, and only 38% had the correct charge.         Why aren’t A/C technicians fixing this pervasive problem? Because, until recently, the tests that have been available to check charge levels have often been misunderstood or poorly applied.That could be changing.         Refrigerant undercharge and overcharge both reduce A/C performance. For example, laboratory testing of capillary tube-controlled equipment indicates that an undercharge of 15% reduces cooling equipment total capacity by 8%–22% and its energy efficiency ratio (EER) by 4%–6%.An overcharge of 10% reduces capacity by 1%–9% and EER by 4%–11%. Laboratory testing of orificecontrolled equipment reveals similar effects.An undercharge of 15% has been shown to reduce EER by 11%; a 15% overcharge by less than 2%.Thermostatic expansion valve (TXV) -controlled equipment is much less sensitive to deviations from the ...

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