Midea V6R VRF Series Service Manual page 49

V6R VRF 50Hz
8.3 Auto Snow-blowing Control
Auto snow-blowing control is used to prevent the fans of stopped outdoor units from destroying by heavy snow.
Timing of auto snow-blowing operation:
T4≤3°C and outdoor units stops time elapse for TA.
Table 3-8.3: Snow-blowing control
Model
8-12HP
14-18HP
When T4＞3°C or the outdoor unit starts operation, the time accumulated for auto snow-blowing is reset to 0.
8.4 Auto Mode and Dual Set Points
Auto mode and dual set points can be set by wired controller with bi-directional communication function. In auto mode, the
indoor unit will operate in heating mode or cooling mode according to the indoor ambient temperature and target set
temperature. When auto mode is set, cooling mode temperature compensation and heating mode temperature
compensation is no longer has any effect.
T1
Tsc
Tsc-1
Tsh+1
Tsh
Tsc: Cooling target set temperature, 26
Tsh: Heating target set temperature, 24
D=Tsc-Tsh
There are three situations according to different D value. Take heating for example:
a) D=0°C
When the indoor ambient temperature(T1) is below Tsh, the indoor unit run in heating mode.
When the indoor ambient temperature(T1) is arrives Tsh+1°C, the indoor unit is heating thermostat OFF.
When the indoor ambient temperature(T1) is arrives Tsh+2°C, the indoor unit is cooling thermostat ON.
Case 1:
Tsc=Tsh=26°C
If the indoor unit operates cooling mode and when indoor ambient drops to 24°C, the indoor unit will change to heating
mode; if the indoor unit operates heating mode and when indoor ambient rises to 28°C, the indoor unit will change to
cooling mode. It is illustrated in Figure3-8.3.
48
TA: Level a
Fan Step
(Menu mode nb5)
15 30min
Figure 3-8.2: Auto mode and dual set points
°C default
°C default
TA: Level b
(Menu mode nb6)
15min
Cooling thermostat ON
Cooling thermostat OFF
Mode change: heating to cooling
H→C H→C
D
Mode change: cooling to heating
Heating thermostat OFF
Heating thermostat ON
Disabled
(Menu mode nb7, default)
/
H→C
: