• On-off thermostat causes wide hysteresis (6 to 10°F) and poor energy efficiency.
• Compressor is larger than needed because it needs to reduce temperature below the set point.
• Enclosure heat loss is higher because temperature must be lowered beyond set point.
• Higher energy usage because of timed de-frost cycle which must be designed for worst case conditions

Variable Speed Compressor Refrigerator

Common Features

• Analog to digital thermostat continuously controls compressor speed in response to heat loss and optimizes energy usage.
• Compressor capacity is optimized for enclosure heat loss only. (Note that rate of cooling is lower than for on-off thermostat refrigerator)
• Enclosure heat loss is minimized by operating at fixed temperature without hysteresis.
• De-frost energy is minimized by comparing evaporator temperature with enclosure temperature and initiating de-frost cycle only when needed.

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