OM 1263 • MICROTECH UNIT CONTROLLER 62 www .DaikinApplied .com
Heat Pump
Table 42: Standard 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
D
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
←
D
Outdoor Fan
Outdoor Fan = 100%
←
←
←
4-Way Valve (Heat Pump)
ON
←
←
←
Outdoor Coil
Expansion Valve (EVO)
(Heat Pump only)
EVO = 0%
A
←
←
Time Duration
10 Seconds
5 Seconds
C
B
A . The outdoor expansion valve is to keep the suction superheat between 3 .6°F and 12°F .
B .
Standard initialization lasts a maximum of 600 seconds. It is completed early anywhere between 10 and 600 seconds if
discharge pressure is high (above 384 psi) or the 4-way valve has been seated for 60 seconds (differential pressure above
57 psi) .
C .
Step 3 ends when the minimum Step 16 is reached, differential pressure is greater than 26 psi for 3 seconds, or 3 minutes
have elapsed since the start of step 3 .
D . Inverter compressor speed is increaded until the 4-way valve is seated (discharge minus suciton pressure > 57 psi) .
Comp3 is always OFF .
See page 50 for
more information about what is a compressor
“step”.