
2WAY VRF SYSTEM
Control Functions
1
- 20
1
2
3
4
5
6
7
8
9
2WAY VRF SYSTEM
Control Functions
5. Outdoor Unit Fan Control
(2) Fixed Initial Fan Mode
For the first 30 seconds after operation starts, the mode is fixed at the initial mode which was calculated from the
relationship between the outdoor air temperature and the outdoor unit horsepower.
If the outdoor unit horsepower (compressor capacity) changes dramatically, the initial mode may be recalculated
and may be again fixed for 30 seconds.
(3) Operation after Fixed Initial Fan Mode
After the fixed initial fan mode, the fan mode is increased or decreased according to the operating conditions.
3-1. Cooling operation
* The fan mode is always increased when the detected high pressure sensor temperature is 114.8°F (46°C) or
higher.
Fan mode is increased when the detected high pressure saturated temperature is high, and is decreased when
the high pressure saturated temperature is low.
The fan mode may be decreased when the system detects refrigerant shortage at an indoor unit.
During cooling operation, if the fan mode becomes “0” and this condition maintains for 3 minutes, the fan mode is
changed to “1”.
3-2. When all indoor units are operating in heating mode
If the pressure sensor temperature is low, the fan mode is increased at regular intervals.
If the pressure sensor temperature is high, the fan mode is decreased in order to prevent excessive loads.
The fan mode may be increased when the liquid temperature of outdoor unit heat exchanger drops to
1.8deg F (1deg C) or below.
5. Outdoor Unit Fan Control
1-3. Silent mode
This unit includes 2 types of silent modes.
See the table under the section “(1) Fan Mode” for maximum fan mode in silent mode.
Selecting the silent mode results in operation that gives priority to reducing noise, because these modes involve
restrictions on outdoor unit fan modes, the capacity will be somewhat reduced. (It may sometimes become a
maximum of -5 hp.)
* Maximum fan mode and frequency in silent mode
Type of outdoor unit
72
96
120
144
Fan mode
9
10
11
11
Frequency (Hz)
48.1
64.4
41.4
54.9
* To activate this function, it is necessary to set it to each outdoor unit.
CODE: 05
Setting No.
Mode
External input to PCB
Silent mode
0
Invalidity (Factory preset mode)
-
-
1
Silent priority
Necessary
Silent mode
2
-
3
Unnecessary
Silent mode
4
-
5
Capacity priority
Necessary
Silent mode
6
-
7
Unnecessary
Silent mode
8
-
* When the setting is "external input to PCB necessary", this function works by short circuiting "SILENT" pins.
* When the setting is "external input to PCB unnecessary", this function always works.
* When the setting is "silent priority", max. fan mode is decided in the following formula.
Max. fan mode = 13 - ( 35 – Ambient temperature) / 2
However, minimum fan mode is “6”, maximum is “13”. (When high static pressure mode, max is “15”)
* When the setting is "capacity priority", this function works excluding the following conditions.
Condition that silent mode interrupts
Heat exchanger [condenser] of outdoor unit: Ambient temperature ≥ 100.4°F (38°C)
Heat exchanger [evaporator] of outdoor unit: Ambient temperature ≤ 35.6°F (2°C)
This function will be useful for nighttime in summer.
SM830237-07_北米向け2WAY_VRF.indb 20
18/06/19 18:55:32