HVAC Engineering Fundamentals
Comprehensive technical specifications for air conditioning system design and implementation.
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Cooling Load Calculations
- BTU/hr = Area × Height × Factor × (ΔT)
- Sensible Heat Ratio (SHR): 0.65-0.75
- Latent Load Factor: 0.25-0.35
- Safety Factor: 1.1-1.2 multiplier
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System Performance Metrics
- EER Range: 11.0-14.0 at 95°F
- IEER: Multi-point efficiency rating
- COP: 2.9-3.5 typical range
- Power Usage: 0.8-1.2 kW/ton
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Load Components
- Solar Heat Gain: 200-300 BTU/ft²
- Occupancy Load: 250 BTU/person/hr
- Equipment Heat: 3.412 BTU/W/hr
- Infiltration: 0.5-1.0 ACH typical
Technical Specifications
Critical system parameters and operational characteristics:
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Refrigeration Cycle
- Subcooling: 10-15°F optimal
- Superheat: 8-12°F target
- Compression Ratio: 2.5-3.5:1
- Evaporator ΔT: 15-20°F design
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Air Distribution
- Supply Air: 350-400 CFM/ton
- External Static: 0.5-1.0 iwc
- Velocity: 700-900 FPM trunk
- Return Air: 90-110% of supply
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System Controls
- Deadband: ±2°F typical
- Staging Differential: 4-6°F
- Cycle Rate: 2-3 cycles/hour
- Humidity Control: 45-55% RH
Installation Standards
Critical specifications for proper system installation and operation:
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Mechanical Requirements
- Line Set Sizing: ⅜"-⅞" typical
- Minimum MERV Rating: 13
- Condensate Slope: ¼" per foot
- Vibration Isolation: 95% min
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Electrical Specifications
- MCA: 125% of FLA
- MOCP: 175-225% of FLA
- Voltage Range: ±10% nominal
- Phase Imbalance: ≤2% max
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Performance Verification
- Pressure Test: 450 PSIG N₂
- Vacuum Level: 500 microns
- Temperature Split: 18-22°F
- Charge Tolerance: ±3 oz