Defrost Operation; Drain Pan Heater (Option) - Daikin RXYQ-TA Series Service Manual

SiUS341615E
7.4

Defrost Operation

To defrost the outdoor heat exchanger while in evaporator, the defrost operation is conducted to recover the
heating capacity.
Tc : High pressure equivalent saturation temperature
Te : Low pressure equivalent saturation temperature
Starting conditions
Referring to the set conditions for the following items, start the defrost operation.
• Heat transfer coefficient of the outdoor heat exchanger
• Heat exchanger deicer temperature (Tb)
• Timer (Set to 2 hours at minimum.)
Furthermore, the heat transfer coefficient of the outdoor unit Evaporator is computed from Tc, Te, and
compressor loads.
Part Name
Inverter compressor 1
Inverter compressor 2
Inverter fan 1
Inverter fan 2
Electronic expansion
valve (Main)
Electronic expansion
valve (Injection)
Four way valve
Solenoid valve
(Accumulator oil return)
Solenoid valve
(Oil return 1)
Solenoid valve
(Oil return 2)
Ending conditions
: equipped
–: not equipped
∗1: RXYQ96/120TA only
Electronic expansion valve
7.5

Drain Pan Heater (Option)

When the drain pan heater is connected, it operates below.
Operating conditions
•
Outdoor air temperature < 3°C (37.4 °F)
&
•
During defrost operation
Functions and Control
Electric
Symbol RXYQ72-120TA RXYQ144/168TA
M1C
M2C —
M1F
∗1
M2F ( )
Y1E
Y2E
Y1S
Y2S
Y3S
Y4S —
Indoor unit actuator
Thermostat ON unit
Fan Stopping unit
Thermostat OFF unit
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Operation
RXYQ72TA: 266 Hz
RXYQ96/120TA: 188 Hz
RXYQ144/168TA: 252 Hz + 252 Hz
With high pressure
OFF ←→ Step 4 ←→ Step 6
RXYQ72TA: 480 pulses
RXYQ96-168TA: 3,000 pulses
0 pulse
OFF
ON
ON
• A lapse of 15 min.
OR
• Tb > 11°C (51.8°F) continues for 30 sec. or more
During defrost
OFF
OFF
OFF
Defrost EV opening degree
Defrost EV opening degree
Defrost EV opening degree
Special Control
70