A demand defrost control initiates defrost by what method?

A demand defrost control system operates based on the need to manage frost accumulation on the outdoor coil of a heat pump. This helps to maintain efficiency during heating cycles. The method involves monitoring the difference in pressure between the fan compartment and the temperature of the outdoor coil.

When frost builds up on the outdoor coil, it can impede the heat exchange process, lowering the efficiency of the heat pump. The difference in pressure indicates the operational conditions of the system, which can signal that a defrost cycle is necessary. This proactive approach allows the heat pump to enter defrost mode only when needed, thus conserving energy and maintaining optimal performance throughout the heating season.

Other methods listed, such as timing the heating cycle or relying on the thermostat setting, may not accurately reflect when a defrost cycle is truly needed. They also do not account for real-time conditions affecting frost buildup. The energy consumption of the unit could indicate general efficiency but lacks the targeted response necessary for initiating a defrost cycle based on specific environmental factors affecting coil performance.