What is the compression ratio for an R410A heat pump with a suction pressure of 50 PSIG and a head pressure of 285 PSIG?

To determine the compression ratio of a heat pump using R410A, you need to use the suction and head pressures to calculate the ratio. The compression ratio is defined as the ratio of the discharge pressure (head pressure) to the suction pressure.

First, it's essential to convert the pressures from PSIG (pounds per square inch gauge) to PSIA (pounds per square inch absolute) because the absolute pressure is required for calculations. The atmospheric pressure is approximately 14.7 PSIA at sea level. Therefore, you add this to each PSIG reading:

• Suction pressure: 50 PSIG + 14.7 PSIA = 64.7 PSIA

• Head pressure: 285 PSIG + 14.7 PSIA = 299.7 PSIA

Now, calculate the compression ratio:

Compression Ratio = Head Pressure / Suction Pressure

Compression Ratio = 299.7 PSIA / 64.7 PSIA ≈ 4.63

This value rounds to approximately 4.6, which matches the answer choice indicating a compression ratio of 4.6:1. This reflects the efficiency and performance metrics of the heat pump, as a specific compression ratio is integral in understanding the