Compression Ratio Formula:
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Definition: This calculator determines the compression ratio of an HVAC system by comparing the absolute discharge pressure to the absolute suction pressure.
Purpose: It helps HVAC technicians assess compressor performance and potential system issues.
The calculator uses the formula:
Where:
Explanation: The ratio indicates how much the refrigerant vapor is compressed in the system.
Details: Proper compression ratio ensures efficient operation, prevents compressor damage, and maintains system performance.
Ideal Range: Typically 3:1 to 5:1 for most HVAC systems.
Tips: Enter both absolute pressures (psia) measured at the compressor. Remember psia = psig + 14.7.
Q1: Why is compression ratio important?
A: High ratios increase discharge temperatures, reduce efficiency, and can damage compressors.
Q2: What causes high compression ratios?
A: Low suction pressure, high discharge pressure, or both.
Q3: How do I lower a high compression ratio?
A: Increase suction pressure (larger suction lines, proper refrigerant charge) or reduce discharge pressure (clean condenser, proper airflow).
Q4: What's the difference between psig and psia?
A: Psig is gauge pressure (relative to atmosphere), psia is absolute pressure (including atmospheric pressure).
Q5: When should I be concerned about the ratio?
A: When it exceeds the manufacturer's recommended maximum (often 10:1 for reciprocating compressors).