Daikin DPS Installation And Maintenance Manual page 90

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 64: Pumpdown State
Compressors
Outdoor fan
4 way valve
Outdoor Expansion Valve (EVO) (Heat Pump only)
SVR (Heat Pump only)
SVB
Indoor Expansion Valve (EVI)
Time Duration
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 finished 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 65: Standby for Restart State
Compressors
Outdoor Fan
4 way valve, outdoor expansion valve (EVO) (Heat
Pump only) and SVB
SVR (HeatPump only)
Indoor expansion valve (EVI)
Time Duration
OM 1141-3 • MICROTECH UNIT CONTROLLER
Step 1
Inverter Compressor speed = maximum
Comp3= OFF
Normal control
Off
Outdoor Expansion Valve position = 100%
Closed
Open
Closed
A
Stage 1
Inverter Compressor speed = 0% and Comp3 OFF
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
Off or closed
Open if saturated discharge pressure > 427 psi when
entering Standby for Restart state
Closed otherwise
Closed
5 seconds
90
Inverter Compressor speed = minimum
Outdoor Expansion Valve position = 50%
Open except Closed after 10 seconds
if suction super heat < 41°F
Remainder of Clg Stg Time
Clg Stg Time (default=5 minutes)
o ' g
perator s uIde
Step 2
Comp3= OFF
←
←
Closed
Closed
B
Stage 2
←
←
Off or closed
Closed
Closed
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