Defrost Operation - Daikin VRV III REYQ8PY1 Service Manual

Special Control
3.4

Defrost Operation

[Start conditions]
Referring to the following conditions, start defrost operation.
• When there is a decrease in the coefficient of heat transfer of outdoor unit heat exchanger
• When there is a drop in the temperature of outdoor unit heat exchanger outlet (Tb)
&
• When the low pressure stays low for a certain amount of time (2 hours minimum)
Furthermore, the thermal conductivity of outdoor unit heat exchanger is calculated by Tc, Te, and compressor loads.
Defrosting outdoor unit actuator
Compressor 1
Compressor 2
Compressor 3
Outdoor unit fan 1
Outdoor unit fan 2
Four way valve (for heat changer
selection)
Four way valve (for high- and low-
pressure gas pipe selection)
Electronic expansion valve (main) EVM
Electronic expansion valve
(subcooling)
Electronic expansion valve
(refilling refrigerant)
Solenoid valve (main bypass)
Solenoid valve (hot gas)
Solenoid valve (liquid pipe of
refrigerant regulator)
Solenoid valve (gas discharge
pipe of refrigerant regulator)
Solenoid valve (drain pipe of
refrigerant regulator)
Solenoid valve (discharge pipe of
refrigerant regulator)
End conditions
118
Elect.
symbol
Symbol
REYQ REMQ
M1C M1C REYQ8•10•12P: 232Hz+ON
REYQ14•16P: 232Hz+232Hz
— M2C M2C REMQ8P: 210Hz
REMQ10•12P: 210Hz+ON
REMQ14•16P: 202Hz+ON+ON
— M3C
M1F M1F
Pcmax>2.45MPa
—
Pcmax>3.04MPa
M2F M2F
20SA Y2S
Y3S OFF
Y9S
20SB Y8S Y2S Holds
Y1E
Y3E Y1E 1375pls
Y2E
EVT Y3E SH control
Y5E
EVJ Y4E Y2E 80pls
SVE Y5S
Y6S ON
Y10S
SVP Y4S Y5S OFF
SVL Y3S Y4S 0pls
SVG Y1S Y1S 0pls
SVO Y7S Y7S 0pls
SVT Y6S Y8S 0pls
REYP8 to 16P (by unit)
or
REMQ8 to 12P (by unit)
or
REMQ14 and16P (by unit)
or

Defrost operation

OFF
Pcmax<2.36MPa
FANSTEP4
Pcmax<2.95MPa
FANSTEP6
• 6 min. and 30 sec.
• Tb > 11°C continues for a
period of 90 consecutive sec.
• Pc_max > 3.04MP
• 5 min. and 30 sec.
• Tb > 11°C for a period of
10 consecutive sec.
• Pc_max > 3.04MPa
• 5 min. and 30 sec.
• Tb > 11°C for a period of 30
consecutive sec.
• Pc_max > 3.04MPa
Si37-701
Operation after defrost
REYQ8•10•12P: upper limit
124Hz(STD Holds)
REYQ14•16P: 232Hz+232Hz
REMQ8P: 210Hz
REMQ10•12P: 210Hz+ON
REMQ14•16P: 210Hz+ON+ON
OFF
Pcmax>2.45MPa Pcmax<2.36MPa
FANSTEP4
Pcmax>3.04MPa Pcmax<2.95MPa
FANSTEP6
OFF
Holds
0pls
0pls
80pls
OFF
OFF
0pls
0pls
0pls
0pls
• 30 sec.
or
• Pc_max>3.04MPa
Function