10
SUPERHEAT CONTROL
This function is used to adjust the opening of the electronic expansion valve so that superheat (SH) will reach a targeted superheat
value (SHS).
The superheat is calculated by reading the temperature of the gas pipe thermistor (T2B) and the temperature of the liquid pipe
thermistor (T2A) of the indoor unit.
SH = T2B - T2A SH: Evaporator outlet superheat (°F)
SHS: Target SH value T2B: Indoor unit gas pipe temperature (°F)
T2A: Indoor unit liquid pipe temperature (°F)
DSH: Discharge superheat of outdoor unit
40VMC, F, H, I, L, M, R, U, V, W Series
Initial SHS = 9°F for the first ten minutes after outdoor unit starts. SHS corrections are made according to the following logic:
Table 8 —SHS Correction by DSH of Outdoor Unit
HEATING OPERATION
Startup and Stop Control of 5000P EEV
When the indoor unit receives any of the following signal:
• signal to turn off
• indoor unit error signal
• indoor unit turns to thermo-off
The EEV’s control uses the following logic:
• If the outdoor unit shuts down without heating capacity requirement:
The EEVs keep the previous opening for three minutes.
Then EEVs conduct 300P opening (EEV whose opening is not equal to 0 will close to 0P first, then open to 300P).
• If the heating capacity requirement of the outdoor unit is not equal to 0:
The EEVs keep previous opening for 25 seconds after the indoor unit turns off, and then close to -16P to reset the opening and
open to 72P (Standby).
When the indoor unit receives the signal to turn ON, the EEV’s control uses the following logic:
Fig. 17 —For Heat Pump and Single Phase-VRF
SHS
Correction
Heat Pump VRF, Single-Phase VRF Heat Recovery
'6+
6+6
6+6
6+6
6+6
'6+
6+6
6+6
6+6
6+6
All the
indoor units
open to OP
Compressor starts > 200s
Pc > 362 psi
Pc-Pe > 123 psi
T2a > 89.6°F
Heat Pump VRF
Single Phase VRF
requirement = 0
Capacity
requirement = 0
Startup Signal
72P standby opening
First open to max. opening
for one minute, and then
open to initial opening for
4 minutes
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