General Assist Technical Reference
Indoor Unit AUTO Changeover
How the master indoor unit automatically selects cooling or heating
Technical explanation of AUTO changeover temperature logic and the 6-minute thermostat OFF condition
When AUTO changeover is enabled, the system determines whether to operate in cooling or heating by comparing the master indoor unit's room temperature with its set temperature.
1. AUTO Changeover Setup
For indoor-unit AUTO changeover operation, the following configuration is required:
| 1 | Set the outdoor unit operation mode management to "Management by indoor unit" using the applicable outdoor unit DIP switch. |
| 2 | Set the master indoor unit using the wired remote controller. |
| 3 | Cooling or heating is then determined from the difference between the master indoor unit's set temperature and its room temperature. |
Important: The master indoor unit is the reference used to determine whether AUTO operation requires cooling or heating.
2. Temperature Changeover Logic
The AUTO changeover decision is based on a ±2°C temperature differential around the master indoor unit's set temperature.
Ts = Master Indoor Unit Setting Temperature
| Room Temperature Condition | AUTO Decision |
|---|---|
| Room temperature ≥ Ts + 2°C | COOLING operation |
| Room temperature ≤ Ts − 2°C | HEATING operation |
| Room temperature is between Ts − 2°C and Ts + 2°C | No new heating or cooling changeover threshold has been reached. |
Cooling selection
Room Temperature ≥ Set Temperature + 2°C
→ COOLING OPERATION
Heating selection
Room Temperature ≤ Set Temperature − 2°C
→ HEATING OPERATION
3. 6-Minute Thermostat OFF Rule
Once the system is operating in either heating or cooling, AUTO changeover does not continuously switch between modes each time the room temperature moves.
The thermostat must remain OFF for 6 minutes or longer before the AUTO changeover temperature conditions are judged again.
This timing condition applies in both:
- Heating operation
- Cooling operation
4. AUTO Changeover Sequence
| 1 | AUTO changeover operation starts. |
| 2 | The controller compares the master indoor unit's room temperature with its set temperature. |
| 3 | If room temperature is 2°C or more above the set temperature, cooling is selected. |
| 4 | If room temperature is 2°C or more below the set temperature, heating is selected. |
| 5 | The selected heating or cooling operation continues according to system demand. |
| 6 | When the thermostat remains OFF for 6 minutes or longer, the system returns to the AUTO changeover temperature judgement. |
| 7 | If the system stops or an operation command other than AUTO changeover is issued, the AUTO changeover sequence is no longer followed. |
5. Example
If the master indoor unit is set to 22°C:
| Room Temperature | Condition | Result |
|---|---|---|
| 24°C or higher | Room ≥ 22°C + 2°C | Cooling |
| 20°C or lower | Room ≤ 22°C − 2°C | Heating |
| Above 20°C and below 24°C | Within the ±2°C changeover band | No new mode threshold reached |
The 2°C differential is the AUTO changeover threshold. It should not be interpreted as the normal thermostat differential for maintaining the room temperature once heating or cooling has been selected.
6. Quick Reference
| Mode management | Management by indoor unit |
| Temperature reference | Master indoor unit |
| Cooling threshold | Room ≥ Ts + 2°C |
| Heating threshold | Room ≤ Ts − 2°C |
| Re-evaluation condition | Thermostat OFF for 6 minutes or longer |