Airwell /yaz218, Service Manual

Page: 53 / 84

CONTROL SYSTEM
11-14
SM YAZ218 1-A.2 GB
Note: ‘On’ state has higher priority.
11.5.7 Thermodynamic Protections
Protection level definition
Five protection levels are defined:
Normal – No protection status is ON.
Stop-Rise (SR) – System is in protection, first level
D1 - System is in protection, second level
D2 - System is in protection third level
Stop-Compressor (SC) – System is in protection fourth level
11.5.8 IDU Protection Level
The overall protection level of the indoor units will be the worst protection status among the
all indoor units.
11.5.9 IDU Protections
11.5.9.1 Indoor Coil Defrost Protection
ICT Trend
ICT
Fast
Increasing
Increasing No change Decreasing
Fast
Decreasing
ICT < -2 SC SC SC SC SC
-2 ≤ ICT < 0 D1 D1 D2 D2 D2
0 ≤ ICT < 2 SR SR D1 D2 D2
2 ≤ ICT < 4 SR SR SR D1 D2
4 ≤ ICT < 6 Norm Norm SR SR D1
6 ≤ ICT < 8 Norm Norm Norm SR SR
8 ≤ ICT Normal
11.5.9.2 Indoor Coil over Heating Protection
ICT Trend
ICT
Fast
Decreasing
Decreasing No Change Increasing
Fast
Increasing
ICT > 55 SC SC SC SC SC
53 < ICT ≤ 55 D1 D1 D2 D2 D2
49 < ICT ≤ 53 SR SR D1 D2 D2
47 < ICT ≤ 49 SR SR SR D1 D2
45 < ICT ≤ 47 Norm Norm SR SR D1
43 < ICT ≤ 45 Norm Norm Norm SR SR
ICT ≤ 43 Normal
OAT
Base Heater at heating mode
ON
OFF
-2 0