In a refrigeration system that uses chilled water as the cooling medium, a gauge reading the refrigerant saturation pressure is most useful for estimating which of the following?

• A. Refrigerant condensation pressure
• B. Temperature of chilled water being pumped to the spaces being cooled
• C. Temperature in the refrigerant loop
• D. Pressure drop in the chilled water system

Answer: (B)

When a refrigerant boils in the evaporator, its pressure corresponds to a specific saturated temperature. The chilled-water coil transfers heat to the refrigerant, so the water leaving the coil is cooled toward that evaporating temperature. Therefore, the saturation pressure on a refrigerant gauge in a chiller is a good proxy for the temperature of the chilled water being pumped to the spaces.

This gauge doesn’t directly indicate the condenser-side conditions, the overall refrigerant loop temperature, or the pressure drop in the chilled-water piping, which is why those options are not as useful in this context.