OM 1263 • MICROTECH UNIT CONTROLLER 64 www .DaikinApplied .com
Heat Pump
Table 44: Alternate Initialization Sequence, 16–28 Tons
Device
Step 1
Step 2
Step 3
Step 4
Inverter Compressor & Comp3
Inverter Compressor Speed =
Minimum Comp3 = Off
Inverter Compressor Speed =
Step 2 Comp3 = Off
Inverter Compressor Speed
= Increasing 1 step every 5
seconds if PTD-PTD < 26 PSI
Comp3 = Off
A
Inverter Compressor Only
Inverter Compressor Speed =
Minimum
If OAT ≤59°F, Inverter
Compressor Speed = Smaller
of Step 12 or Maximum
If OAT >59°F, Inverter
Compressor Speed = Minimum
A
NA
Outdoor Fan
Outdoor Fan = 100%
←
←
←
4 Way Valve (Heat Pump)
ON
←
←
←
Outdoor Coil
Expansion Valve (EVO)
(Heat Pump only)
B
←
←
←
Time Duration
5 Seconds
5 Seconds
C
←
A . Inverter compressor speed is increased until the 4-way valve is seated (discharge minus suction pressure > 57 psi) and as
long as discharge presure is below 221 psi . Inverter compressor speed is also increased if the discharge pressure remains
below 171 psi . Comp3 turns on if the inverter compresor speed is at maximum and those conditions are not met . Comp3
turns back off after 20 seconds if the discharge pressure rised above 221 psi.
B . The outdoor expansion vavle is to keep the suction superheat between 3 .6°F and 5 .4 °F
C .
Alternate initializaiton lasts a maximum 15 minutes. It is completed early anywhere between 10 seconds and 15 minutes if
once the 4-way valve is seated (differential pressure above 57 psi) and superheat is above 18°F or discharge pressure is
above 384 psi .
Summary of Contents for MicroTech III DPS
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