How long must the crankcase heat be energized for a scroll-chiller compressor according to manufacturer requirements?

For a scroll-chiller compressor, the manufacturer typically recommends that crankcase heat be energized for a minimum of 24 hours prior to starting the unit. This duration is crucial as it allows the refrigerant in the crankcase to warm up, preventing liquid refrigerant from entering the compressor during startup. Liquid refrigerant can cause what is known as "liquid slugging," which can harm or destroy the compressor.

Energizing the crankcase heat for 24 hours ensures that the oil in the crankcase reaches the appropriate temperature to provide proper lubrication when the compressor starts up. This practice helps maintain the longevity and operational reliability of the compressor, leading to a more efficient system overall.

While other durations such as 12, 18, or 36 hours could be considered, they do not align with the standard recommendations set by manufacturers for scroll-chiller compressors. The specified 24 hours balances effective warming of the crankcase while also managing operational readiness efficiently.