Vital to the operation of the refrigeration cycle, superheat must be maintained and stable to protect the compressor.  We all know that the heart of the system cannot compress liquid (slug) without bad things happening.  This would represent low/no superheat.  But, did you know high superheat can cause valve and compressor problems as well?  No matter the reason for attaching your gauges to the system, you must check the superheat, in the air-conditioning cycle.

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Comment by Bob Blanchette on January 16, 2014 at 2:12pm

Depends on type of system. TXV and Fixed orifices have different charging methods. As Steven stated airflow needs to be addressed, in many systems it falls WAY short. 3+ ton systems seem to be the worst offenders.

Comment by Steven Lewis on January 16, 2014 at 8:12am

Super heat readings without knowing airflow only gives you 1/2 the equation.  Dirty filters/ low airflow/refrigerant overcharge/low temp in building or low outdoor temp will all affect the superheat of the system.  If the superheat is out of range (high or Low) then the cause needs to be determined and corrected.  We all say that the house is a system but in HVAC  I say everything is Relative.  When you change one condition, it effects everything else, so it not the superheat temp but how it relates to the other information you gather.  As an example an A/C can have a high super heat of 20 if the indoor temp is high 88+ and outdoor temps are high as well and then when the unit has the house cooled down and running under normal conditions the superheat will be in normal range ( approx 8)  If you tried to charge the unit to reach the 8' you  would have vastly overcharged the system and dramatically raised its operating costs and shortened it life while making the homeowner uncomfortable as well.

Comment by Eric Kjelshus on January 10, 2014 at 6:34pm

I had a printer ask for just 2' superheat +-1'  to keep the paper very dry and never shut down the air handler/AC unit no case heater.    Most ask for 8'+ up to 30' superheat  next to the compresser.  so whats the deal?

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