Wayne's Brain™ Air Conditioner Analyzer updated 6-9-18

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Update steady state values every 10 minutes

 OD °F   Refrigerant / System SEER   ID Return Air °F (at coil)   ID Supply Air °F (at coil)   ID Coil
    DB  WB   DB WB  
High Pressure Source   Discharge Line °F  ┌─────┐ ◄—— Vapor Line °F
═════╩═ ═════              Suction Line °F     ╔═══╩═ ════════════════
═══════════════                ═══ ═══ ═╗║   ═══════════════
═══Condenser════                 ║║─┐ ════Evaporator═══
══ ══                │║   ══ ══
═════ ═════                │╚ ═════ ═════
═══ -14~700psig ═══ ┌──▬──┐  └──┘ ═══ -14~500psig ═══ Manufacturers intended TXV subcooling
Filter/dryer upstream Metering device upstream ═══════════════ Compressor Accumulator ═══════════════
  Liquid Line °F ——►    ___
══════════════════════╩═ ═══════════════════ ═ or ═ʘ═══════
 
  Metering device  
 
 
 
Evaporator Superheat Normal TXV superheat is 10 - 20°
 
Evaporator & Return TD Normal evaporator saturation temperature is 25 - 35° below return air DB for 13 seer & up
 
Condenser Subcooling Manufacturers intended TXV subcooling is 10°
 
Condenser & Outdoor TD Normal condenser saturation temperature for 13 seer & up is 7 - 20° over OD temperature
 
Compression Ratio Normal compression ratio for 13 seer & up is 1.7 to 3.1
 
Indoor Air Delta Temp. ID dry and wet bulb temperatures are needed to determine the target indoor air ΔT
 
 
 
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Legend: Adjustable Parameters
٭ Adjustable parameters modified for temperatures
or humidity outside of typical design conditions
    Too low    Normal Too High
  if less than if within if greater than
        TXV superheat     -    
No remedy suggested. Parameters are in range   subcooling     10 - 13   16  
    Fixed Orifice subcooling     17   22  
Somewhat or a little out of range. Use caution
with systems that otherwise perform satisfactorily
  13 seer & up  
 
  Evaporator Temperature Difference = Evaporator − Return air
Remedy or repair action is recommended   13 SEER & up     -    
      12 SEER or less     -    
Pressure access port      
Δh Delta Enthalpy (change in total heat content of air) Condenser Temperature Difference = Condenser − Outdoor air
ΔT Delta Temperature (sensible heat change of the air)     13 SEER & up     -    
CTD Condenser Temperature Difference (from outdoor air)      11 and 12 SEER     -    
CR Compression Ratio     9 and 10 SEER     -    
CSH Compressor Superheat (entering compressor)     8 SEER or less     -    
CST Condenser Saturation Temperature                
DST Discharge Saturation Temperature Compression ratio = (high + ambient) ÷ (low + ambient)
DB Dry Bulb temperature   13 SEER & up     -    
ETD Evaporator Temperature Difference (from return air)   11 and 12 SEER     -    
ESH Evaporator SuperHeat (at insulated vapor line)   9 and 10 SEER     -    
EST Evaporator Saturation Temperature   8 SEER or less     -    
FO Fixed Orifice  
ID Indoor Tolerance for thermometer/pressure gauge calibration  
OD Outdoor Air Temperature (entering condenser) Tolerance for fixed orifice target superheat temperature  
RA Return Air temperature (entering evaporator) Tolerance for target evaporator air delta temperature  
SA Supply Air temperature (leaving evaporator) Tolerance for target or manufactures TXV subcooling  
SC Subcooling Tolerance for nominal CFM calculated from Δh  
sCFM Standard Air Cubic Feet per Minute Estimated temperature drop for filter/dryer  
SH Superheat Estimated temperature drop for metering device  
SHR Sensible Heat Ratio Minimum temperature for a fully charged evaporator  
TD Temperature Difference (of refrigerant and air) Maximum refrigerant  temperature entering compressor  
TSA Target Supply Air (temperature from ΔT chart) Min. temp. difference between max. TXV SC and CTD  
TXV Thermal expansion Valve R-22 estimated percentage of condenser pressure drop %
WB Wet Bulb temperature R-410a estimated percentage of condenser pressure drop %
  Maximum suction line temperature above vapor line  
Notes:   FALSE     (all temperatures Fahrenheit)
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This analyzer incorporates a flexible range for evaporator and condenser temperature differences and system compression ratios. This enables it to analyze a wide range of indoor and outdoor conditions. It has the ability to diagnose over forty different issues including a combination of issues. It will provide a list of possible causes and recommendations.
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This analyzer can be customized to a manufacturers model lineup and/or specific system. Send inquires to "wayne"(no space)"pendergast" at the domain name "comcast" with a dot, then "net".
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Minimal evaporator pressure drop is not considered in calculations.
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Run system on high stage and long enough for liquid refrigerant to un-migrate from crankcase, vapor line, coils and accumulator.
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Return air wet bulb temperature is essential for diagnosis, humidity greatly affects the indoor coil which affects the entire system.
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Record traversed average temperature of moving air shaded from radiant heat, (sun, body, heat exchanger, heater coil etc.) Use clamp style probes for taking pipe temperatures.
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Discharge line temperature should be 225°F or less, 6" from compressor, if higher, check the manufacturer’s maximum.
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When liquid refrigerant is present, its saturation temperature dictates the pressure. This saturation temperature is affected by heat absorption or rejection (airflow), the compressors ability to pump, and the metering devices ability to allow or restrict flow.
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When adding refrigerant, it's best to open the charging valve to a pressure at, or just above, the desired EST. Letting the low side of the system "see" a high tank pressure can extend the time it takes for the refrigerant to stabilize.
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If a steady state condition is not achievable, an inverted trap may be missing from the top of the vapor line riser, liquid traps may be in the horizontal vapor line, non-condensables may be in the system, or an oversized (hunting) TXV may be the cause.
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For A/C units, every 1º of added subcooling without raising condensing pressure, produces an average increase of .5% system efficiency. Increasing both subcooling and condensing pressure (more than necessary to feed the metering device) reduces efficiency. For heat pumps, use the manufacturers recommended subcooling value (correct charge in cooling assures correct charge in heating).
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Compressor amperage depends on both the rate of refrigerant flow and the difference in pressure. Without a significant change in flow, the compressor amperage will follow the compression ratio, when the CR is high the amperage will be high and vice-versa.
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Flowing bubbles in a liquid line sight glass while subcooling is measured indicates non-condensables, impure refrigerant, or calibration error. A single bubble is likely due to expansion in the sight glass.
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Calculations assume a pure refrigerant but can indicate the presence of non-condensables or mixtures. 
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Psychrometric calculations made using .075 ft³/lb density and the perfect gas relationship for dry and moist air. Ideal Gas Law: pV=nRT
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This calculator is a useful tool for assisting a technician with diagnostics and repairs, but it is the technicians responsibility to verify the validity of the analysis made by this application.
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