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Calcimator

Refrigerant Charge Calculator

Evaluate refrigerant charge status using subcooling and superheat measurements for TXV and piston metering devices.

Inputs

°F
°F

ASHRAE Refrigeration Handbook: TXV systems target subcooling 8–12°F; verify against manufacturer charging chart

°F
°F
ft

Results

Charge Status

2 (1=Low, 2=Correct, 3=High)

Estimated Adjustment

0 oz

Subcooling Deviation0 °F
Superheat Deviation0 °F
How to Use This Calculator
  1. Enter Measured Subcooling, Target Subcooling, and Measured Superheat.
  2. Set Target Superheat, Lineset Length, and Metering Device.
  3. Review Charge Status ((1=Low, 2=Correct, 3=High)) and Estimated Adjustment (oz).
  4. Use Subcooling Deviation (°F) and Superheat Deviation (°F) to inform your decision.

What each input means

Measured Subcooling
Measured liquid line subcooling (condenser saturation temp minus liquid line temp).
Target Subcooling
Manufacturer's specified target subcooling for TXV systems per ASHRAE Refrigeration Handbook and manufacturer charging charts. Typically 8–12°F for TXV; shorter linesets tend toward lower values. Always use nameplate or charging chart.
Measured Superheat
Measured suction line superheat (suction line temp minus evaporator saturation temp).
Target Superheat
Target superheat per manufacturer or charging chart. Typically 10–15°F.
Lineset Length
Total length of refrigerant lineset. Standard is 15 ft; additional length may require extra charge.
Metering Device
Metering device type: 1 = TXV (use subcooling method), 2 = Piston/Cap tube (use superheat method).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Measured Subcooling = 10, Target Subcooling = 10, Measured Superheat = 12, Target Superheat = 12 = 6 input(s) provided
  2. Calculate Charge Status
    Charge Status
    2 = 2
  3. Calculate Estimated Adjustment
    Estimated Adjustment
    0 = 0
  4. Calculate Subcooling Deviation
    Subcooling Deviation
    0 = 0
  5. Calculate Superheat Deviation
    Superheat Deviation
    0 = 0

Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.

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