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There are many system checks you need to take in consideration when you are troubleshooting a system and one of the most important check is compressor superheat. How you take this check is by taking a temperature reading 6 inches (150mm) from the compressor suction service valve and subtract the converted pressure the dew point temperature.
Example (R449): You have 30F temperature 6” from suction service valve and your pressure is 47 psig which converts to 22F you have 8F superheat. 30F-22F=8F
Example (R449): You have -1C temperature 150mm from suction service valve and your pressure is 3.26 bar which converts to -5.5C you have 4.5K superheat. -1C-(-5.5C) = 4.5k
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