Summary: UTY-TTRX Thermostat Converter Offset Settings

Purpose:

The UTY-TTRX thermostat converter allows a third-party thermostat to control a Fujitsu mini-split system. However, temperature differences may arise between the thermostat sensor and the indoor unit sensor. Since the system satisfies based on whichever sensor reaches the set temperature first, this can cause inconsistencies.

To ensure the third-party thermostat has primary control, offset adjustments can be made to minimize the impact of the indoor unit's sensor.

Offset Adjustments:

• Cooling Offset: Setting a -8°F (-4°C) offset ensures the thermostat sensor controls cooling in almost all situations.
• Heating Offset: Setting a +8°F (+4°C) offset ensures the thermostat sensor controls heating in almost all situations.
• These adjustments prevent the indoor unit's thermistor from interfering with the thermostat’s temperature control.

Function Settings Table:

• Function 30 (Cooling) / 31 (Heating) allows offset adjustments ranging from -8°F to +8°F.
• Negative values reduce the influence of the indoor unit sensor for cooling, while positive values prioritize the thermostat for heating.

Important Notes:

• Function settings should be adjusted according to the indoor unit’s installation manual.
• Power to the entire system must be turned off for at least two minutes before applying changes.
• Avoid running the system below 64°F (18°C) in cooling or above 88°F (30°C) in heating to prevent operational issues.

See Attached bulletin for more.