I HAVE A westinghouse a/c system in my home,one compresser for the main home an another for the up stairs.A REPAIR MAN COME TO THE HOMEM,CHECKED THE SYSTEM AND SAID I NEEDED MORE FREEON.HE ADDED SOME...
When technicians take an air conditioning course, one of the first
things they learn is to use superheat to charge a fixed orifice air
Superheat is not hard to deal with, but the technician needs to take four good measurements.
get the actual superheat, the technician measures suction line pressure
and suction line temperature. When he reads suction line pressure, he
reads the *F scale on his gauge. That's the boiling
point of that refrigerant at that pressure. To get actual superheat,
subtract the suction line boiling point temperature from the measured
temperature of the suction line.
To read get the required
superheat from the most common A/C manufacturer's superheat charts, the
technician measures indoor "wet bulb" temperature and outdoor air
temperature ("dry bulb"). Using these two temperatures the technician
can look up the required superheat on most A/C manufacturers' superheat
charts. Required superheat's can vary from 5 *F to over 45*F depending
on the conditions (indoor wet bulb and out door dry bulb). The higher
the load, the higher the required superheat.
The technician adds or subtracts refrigerant to decrease or increase the actual superheat to match the required superheat.
is the temperature difference between the boiling point of the
refrigerant in the evaporator and the actual temperature of the
refrigerant gas after the evaporator. It is the "extra" temperature (or
temperature rise) the refrigerant picks up in the evaporator after it
When charging the system, the technician adds as much
refrigerant as he can. But if he adds too much (overcharge), he risks
flooding the compressor with liquid refrigerant.
The biggest risk
of flooding is under low load conditions: low outside temperatures and
low indoor wet bulb temperatures. The refrigerant boils off late in the
evaporator. To make sure the refrigerant is all boiled off before the
end of the evaporator, the the A/C manufacturer's required superheat
chart directs the technician to stop adding refrigerant when the suction
line temperature gets down to within a few degrees of the boiling point
inside the evaporator. The "few degrees" is the superheat. At low load
conditions, the superheat is often specified as five or six degrees.
It's a safety factor to make sure no liquid gets to the compressor.
other load conditions, as determined by outdoor air and indoor wet bulb
temperatures, the required superheat is given by a the superheat chart
supplied by the A/C manufacturer. The higher the temperatures, the
higher the load and the higher the required superheat.
Doing a superheat analysis is the best way to insure that an air conditioner has the proper charge.
Jun 13, 2011 |