LG AR-DR12-05A Installation And Operation Manual page 127

Air Source Heat Pump
Outside Coil Defrost: An air source heat pump periodically needs to initiate a defrost cycle of the outside coil to remove accumulated frost
when operating in heating mode.
Defrost Sequence
1. Initialized: The saturated suction temperature determines when a defrost cycle occurs. For a defrost cycle to initiate, one of the following
must be true:
• The saturated suction temperature is less than set-point; or
• The saturated suction temperature is less than a calculated set-point based on ambient conditions.
At defrost cycle initiation, the following steps occur:
• The reversing valve switches to the cooling position; and
• Condenser fans turn off; and
• The hot gas reheat valve moves to the closed position; and
• Auxiliary heat is enabled.
2. Terminated: The defrost cycle terminates when:
• The saturated suction temperatures of all circuits are greater than or equal to the cancel set-point; or
• The maximum allowed defrost time has been exceeded.
At defrost cycle termination, the unit reverts back to heating mode operation.
3. Auxiliary Heat: Auxiliary heat is enabled with the following constraint: during auxiliary heat, the unit will use heating sources other than
the heat pump in order to maintain the supply air temperature set-point. The electric heat maximum output must meet the auxiliary heat
maximum set-point during defrost.
Controls Lite notifies the third-party controller when auxiliary heat should be enabled.
4. Air Source Heat Pump Heating Lockout: Air source heat pump heating mode is unavailable when:
• The air source heat pump defrost cycle continues for more than the maximum defrost time; or
• A defrost cycle is initiated three (3) times in any one hour period.
• Each strike created by a defrost mode entry clears one hour after the strike occurs.
5. Heating Lockout Reset: The air source heat pump heating lockout resets when:
• The air source heat pump heating lockout occurred more than one hour prior; and
• The outside air temperature increases; or
• The outside humidity decreases.
Due to our policy of continuous product innovation, some specifications may change without notification.
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CONTROLLER
Sequences of Operation
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