Refrigerant Charge Calculator
Calculate target charge with lineset adjustments
Tip: Factory charge is typically based on 25ft of lineset. Add refrigerant for longer runs or remove for shorter runs.
Estimated Factory Charge (Outdoor Unit):
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Based on typical 25ft lineset
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Lineset Information
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oz/ft
Auto-calculated based on liquid line size
Charge Calculation Results
Factory Charge
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Lineset Adjustment
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Total Target Charge
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Metric
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Calculation Breakdown
Factory Pre-charge Length:
25 ft
Actual Lineset Length:
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Equivalent Elbow Length:
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Total Equivalent Length:
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Length Difference:
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Charge Rate:
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Important Notes
- • Always verify factory charge on the equipment nameplate
- • Charge rates vary by manufacturer - check installation manual
- • Final charge should be verified using subcooling/superheat method
- • TXV systems: Charge to 10-15°F subcooling
- • Fixed orifice: Charge to 10-15°F superheat
Refrigerant Charge Rate Reference
| Liquid Line Size | R-410A | R-22 | R-32 | R-454B |
|---|---|---|---|---|
| 1/4" (6.35mm) | 0.6 oz/ft (17g/m) | 0.5 oz/ft (14g/m) | 0.5 oz/ft (14g/m) | 0.6 oz/ft (17g/m) |
| 3/8" (9.52mm) | 1.2 oz/ft (34g/m) | 1.0 oz/ft (28g/m) | 1.0 oz/ft (28g/m) | 1.1 oz/ft (31g/m) |
| 1/2" (12.7mm) | 2.0 oz/ft (57g/m) | 1.7 oz/ft (48g/m) | 1.6 oz/ft (45g/m) | 1.9 oz/ft (54g/m) |
Note: Charge rates may vary by manufacturer. Always refer to installation manual for exact values.
Typical Factory Charge by Capacity
| Capacity | R-410A (typical) | R-22 (typical) | Pre-charge Length |
|---|---|---|---|
| 1.5 Ton (18k BTU) | 56-72 oz (1.6-2.0 kg) | 48-64 oz (1.4-1.8 kg) | 25 ft |
| 2 Ton (24k BTU) | 72-96 oz (2.0-2.7 kg) | 64-80 oz (1.8-2.3 kg) | 25 ft |
| 2.5 Ton (30k BTU) | 88-112 oz (2.5-3.2 kg) | 80-96 oz (2.3-2.7 kg) | 25 ft |
| 3 Ton (36k BTU) | 104-128 oz (3.0-3.6 kg) | 96-112 oz (2.7-3.2 kg) | 25 ft |
| 3.5 Ton (42k BTU) | 120-144 oz (3.4-4.1 kg) | 112-128 oz (3.2-3.6 kg) | 25 ft |
| 4 Ton (48k BTU) | 136-168 oz (3.9-4.8 kg) | 128-160 oz (3.6-4.5 kg) | 25 ft |
| 5 Ton (60k BTU) | 168-208 oz (4.8-5.9 kg) | 160-192 oz (4.5-5.4 kg) | 25-50 ft |
Factory charges vary significantly by manufacturer and model. Always verify on equipment nameplate.
Charging Verification Methods
TXV Systems (Subcooling Method)
- Target: 10-15°F subcooling (varies by manufacturer)
- How to measure:
- Measure liquid line temp near outdoor unit
- Read liquid pressure from gauges
- Convert pressure to saturation temp
- Subcooling = Sat Temp - Liquid Line Temp
- Low subcooling: Add refrigerant
- High subcooling: Remove refrigerant or check for restriction
Fixed Orifice (Superheat Method)
- Target: 10-15°F superheat (varies by conditions)
- How to measure:
- Measure suction line temp near outdoor unit
- Read suction pressure from gauges
- Convert pressure to saturation temp
- Superheat = Suction Line Temp - Sat Temp
- High superheat: Add refrigerant
- Low superheat: Remove refrigerant or check airflow
Charging Tips
- • Weigh in refrigerant for new installations - most accurate method
- • Allow system to run 15-20 minutes before taking readings
- • Indoor temperature should be above 70°F for accurate charging
- • Outdoor temperature affects readings - consult charging chart
- • R-410A must be charged in liquid state (tank inverted or through liquid port)