Control Specification
SiMT041311E
51
Function and Control
2.7
Draught Prevention Control (Hot-Start Function)
Outline
Draught prevention control prevents cold draught when the unit is started up in heating
operation.
Detail
Draught prevention control is conducted by monitoring the indoor heat exchanger
temperature and the set temperature on the remote controller (Ts). When the indoor heat
exchanger temperature drops below a certain level or when the Ts exceeds 20°C, the
minimum frequency of the compressor increases 4 Hz per 120 seconds.
Also, the followings are controlled in order to improve energy efficiency, considering room
thermistor temperature, set temperature, and airflow rate.
After starting heating operation, the unit controls the indoor heat exchanger temperatures
A
and
B
as follows, if the condition
∆
D
≤
4 continues for 60 minutes
∗
Refer to page 45 as for
∆
D.
When the indoor heat exchanger is not hot enough, the indoor fan does not start at the set
speed. The fan speed increases step by step. The limitation of the fan speed is lifted when
the indoor heat exchanger temperature rises above
H
°C.
Condition
A
(°C)
B
(°C)
27°C
≤
Room thermistor temperature
Ts + 2°C
Ts
20°C
≤
Room thermistor
temperature < 27°C
Indoor fan speed > M tap
Ts + 10°C
Ts + 8°C
M tap
≥
Indoor fan speed > L tap
Ts + 9°C
Ts + 7°C
L tap
≥
Indoor fan speed
Ts + 7°C
Ts + 5°C
Room thermistor temperature < 20°C
Ts + 2°C
Ts
C
(°C)
D
(°C)
E
(°C)
F
(°C)
G
(°C)
H
(°C)
10
25
35
37
38
39
A
(˚C) = 51 – 0.6 × Ts
B
(˚C) = 49 – 0.6 × Ts
A
˚C
B
˚C
+ 4 Hz / 120 seconds
– 2 Hz / 120 seconds
(R19765)
Indoor heat exchanger
temperature
LLL
LL
L
ML
M
C
D
E
F
G
H
No limitation
Fan speed
Temperature
(˚C)
(R19674)
Upper
limitation
