M thermal Mono
202008 15
4.4 Four-way Valve Control
The four-way valve is used to change the direction of refrigerant flow through the water side heat exchanger in order to
switch between cooling and heating/DHW operations. Refer to Figures 2-3.1 and 2-3.2 in Part 2, 3 Refrigerant Flow
Diagrams .
During heating and DHW operations, the four-way valve is on; during cooling and defrosting operations, the four-way
valve is off.
4.5 Electronic Expansion Valve Control
The position of the electronic expansion valve (EXV) is controlled in steps from 0 (fully closed) to 480 (fully open).
When the outdoor unit is power on:
The EXV first closes fully, then moves to the standby position (304 steps). After compressor runs for 60-second,
EXV is controlled according to ambient temperature. After a further 180s, EXV is controlled according to different
modes.
When the outdoor unit is in standby:
The EXV is at position 304 (steps).
When the outdoor unit stops:
The EXV is fully closed firstly, then moves to the standby position (304 steps).
4.6 Outdoor Fan Control
The speeds of the outdoor unit fans are adjusted in steps, as shown below.
Table 3-4.3: Fan speed index
Fan speed index
Fan speed (rpm)
Upper fan Lower fan
W1 200 180
W2
280 260
W3
340 320
W4
400 380
W5
460 440
W6
520 500
W7
580 560
W8
640 620
W9
700 680
W10
760 740
W11
820 800
W12
880 860
W13
900 900
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