OM 1263 • MICROTECH UNIT CONTROLLER 66 www.DaikinApplied.com
Pumpdown
Compressor heating operation enters the Pumpdown state before entering the Standby for Restart state from either the
Initialization or Normal Heating state.
The following describes the operation of the compressor heating control devices in the Pumpdown state:
Table 46: Pumpdown State
Step 1
Compressors
Inverter Compressor Speed = Smaller of Step 12 or maximum
Comp3=OFF
Outdoor Fan Outdoor Fan speed = maximum
4 Way Valve (4WV) ON
Outdoor Expansion Valve (EVO) Outdoor Expansion Valve position = 0%
SVR Closed
SVB Open
Indoor Expansion Valve (EVI) Indoor Expansion Valve Control position = 50%
Time Duration See A below
A. Pumpdown is complete after 3 minutes or when the suction pressure drops below 34 psi. Pumpdown is terminated if either
the discharge superheat rises above 230°F or if the Inverter Compressor port temperature rises above 284°F.
Standby for Restart
The Standby for Restart state guarantees at least one Htg Stg Time period elapses before re-entering the Intializaton and Normal
Heating states. The following describes the Standby for Restart state sequence:
Table 47: Standby for Restart State
Step 1 Step 2
Compressors
Inverter Compressor speed = 0%
Comp3=OFF
←
Outdoor Fan
Outdoor Fan speed = 50% if OAT > 86°F when
entering Standby for Restart state
Outdoor Fan speed = 0% if OAT ≤ 86°F when entering
Standby for Restart state
←
4 Way Valve (4WV) ON ←
Outdoor Expansion Valve (EVO) Outdoor Expansion Valve position = 0% ←
SVR Closed Closed
SVB Closed ←
Indoor Expansion Valve (EVI) Indoor Expansion Valve position = 0% ←
Time Duration
5 seconds Remainder of Htg Stg Time
Htg Stg Time (default = 5 minutes)
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