Table of Contents
[5-2 Outdoor Unit Control ]
(4) Evaporation temperature control (Expansion valves LEV2a and LEV2b)
LEV is controlled every 30 seconds so that the temperature at the bypass inlet (TH15) of the BC controller is in a constant
range during heating-main operation.
5-2-11
Expansion valve control (LEV2a, LEV2b, and LEV2d)
The default opening levels of the expansion valves LEV2a and LEV2b are shown in Section [5-2-10 Outdoor Unit Fan Control].
When the following control (1) or (2) is performed during heating-only or heating-main operation, the valves open or close.
(1) Refrigerant equalization control
On the combination models, to equalize the refrigerant amount between OC and OS, the opening levels of LEV2a and LEV2b
are controlled depending on the difference of TdSH between OC and OS. During the refrigerant equalization control, the open-
ing levels of LEV2a and LEV2b change on each unit. The LEV opening levels of the unit having smaller TdSH is lower than
those of the unit with larger TdSH. Therefore, the opening levels of LEV2a and LEV2b are sometimes smaller than the default
opening levels.
TdSH = TH4-Tc
(2) Evaporation temperature control
LEV is controlled every 30 seconds so that the temperature at the bypass inlet (TH15) of the BC controller is in a constant
range during the heating-only or heating-main operation.
5-2-12
Control of Controller Cooling Function (Electronic Expansion Valve )
Control of controller cooling function is performed individually for OC and OS.
The opening of LEV9 is adjusted every three seconds to keep the controller heatsink temperature (THHS) below the threshold
value, which is determined by the setting of the outside temperature (TH7).
5-2-13
Injection Control (Linear Expansion Valve )
LEV4 opening is adjusted every 30 seconds to keep the discharge temperature (TH4) within the predetermined range.
Injection control starts when the outside temperature (TH7) drops below 5°C (41°F).
5-2-14
Control at Initial Startup
When started up for the first time before 12 hours have elapsed after power on, the unit goes into the initial startup mode.
At the completion of the initial operation mode on the OC and OS, they will go into the normal control mode.
(1) Single-outdoor-unit system
20
- chapter 5
Initial startup mode starts.
50
F
60Hz
Completed in the integrated operation time of 35 minutes.
or
F < 50Hz
Completed in the integrated operation time of 90 minutes.
or the discharge superheat (TH4 - Tc) is detected (within
5 minutes of startup) that remains above approximately
25 degrees for one minute .
Initial startup mode complete
HWE18220_GB
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- Error Code [4114]
- Error Code [6840]
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