OM 1263 • MICROTECH UNIT CONTROLLER 56 www.DaikinApplied.com
Pumpdown
When compressor operation is no longer needed, the compressor enters the Pumpdown state before entering the Standby for
Restart state from either the Initialization or Normal Cooling state.
The following describes the operation of the cooling control devices in the Pumpdown state:
Table 39: Pumpdown State
Step 1 Step 2
Compressors
Inverter Compressor speed = maximum
Comp3= OFF
Inverter Compressor speed = minimum
Comp3= OFF
Outdoor fan Normal control ←
4 way valve O ←
Outdoor Expansion Valve (EVO) (Heat Pump only) Outdoor Expansion Valve position = 100% Outdoor Expansion Valve position = 50%
SVR (Heat Pump only) Closed
Open except Closed after 10 seconds
if suction super heat < 41°F
SVB Open Closed
Indoor Expansion Valve (EVI) Closed Closed
Time Duration A B
A. The inverter compressor speed is at maximum with the outdoor expansion valve open, SVR closed, SVB open and the
indoor expansion valve closed for a maximum of 5 minutes. Step 1 is normally nished before 5 minutes when the suction
pressure drops below 72 psi. Step 1 is terminated if the inverter compressor discharge line temperature is above 230°F, the
inverter compressor port temperature is above 257°F or the discharge pressure is above 427 psi.
B. The inverter compressor speed is at minimum, the outdoor expansion valve is open 50% open, SVR closed, SVB open and
indoor expansion valve closed. Pumpdown is normally complete when the suction pressure drops below 36 psi. Pumpdown
is terminated if the inverter compressor port temperature rises above 320°F
Standby for Restart
The Standby for Restart state guarantees at least one Clg Stg Time period elapses before re-entering the Intialization and Normal
Cooling states. The following describes the Standby for Restart state sequence:
Table 40: Standby for Restart State
Stage 1 Stage 2
Compressors Inverter Compressor speed = 0% and Comp3 OFF ←
Outdoor Fan
Outdoor Fan position = 50% if OAT > 86°F when
entering Standby for Restart state
Outdoor Fan position = 0% if OAT ≤ 86°F when
entering Standby for Restart state
←
4 way valve, outdoor expansion valve (EVO) (Heat
Pump only) and SVB
O or closed O or closed
SVR (HeatPump only)
Open if saturated discharge pressure > 427 psi when
entering Standby for Restart state
Closed otherwise
Closed
Indoor expansion valve (EVI) Closed Closed
Time Duration
5 seconds Remainder of Clg Stg Time
Clg Stg Time (default=5 minutes)
To Next Page
Loading...
