Honeywell Home THR842D Wireless Room Thermostat

with ECO energy saving feature

Operating Indicators

Room temperature: Displays the current room temperature (e.g., 20.0°C).

Heating demand indicator: Shows when the heating system is active (?).

Frost protection: Indicates frost protection is active (❄️). Note: Frost protection is not available in cooling operation.

Fault indicator: Signals a system error (⚠️).

Low battery indicator: Alerts when batteries need replacement (?).

RF communication: Indicates wireless connection status (?).

Loss of RF communications: If RF communication is lost, a red LED ? lights up, and the Relay Box operates in failsafe mode, as set by the installer.

Temperature Settings

Set temperature, inquiry: Displays the desired temperature setting.

Set temperature, adjustment: Allows adjustment of the desired temperature using the ⬆️/⬇️ buttons.

Power and Mode Control

Switch ON/OFF: Use the button ▶️/⏹️ to control the thermostat. Frost protection is enabled when the button is pressed.

ECO Energy Saving Feature

Pressing the green ECO button ? activates a timed period at a predefined energy-saving temperature (typically 18°C).

To set the ECO energy savings time period, adjust the duration using the controls (e.g., 1-24 hours).

The display shows the countdown of ECO time remaining (e.g., 5s).

Temporary Manual Override: Pressing the ⬆️ or ⬇️ buttons allows temporary modification of the ECO temperature setting.

To exit ECO mode early, press the green ECO button ? again.

Relay Box Operation

Automatic Operation

The Relay Box operates automatically based on thermostat settings.

Temporary Manual Override

Press the button to temporarily override the current relay position.

LED Indicators:

Green LED on (?): Relay is ON (e.g., heating is active).
Green LED off: Relay is OFF.

Product Information

Power Source: 2 x LR6 AA Alkaline batteries.

Manufacturer: bk-electronic GmbH, Germany.

Country of origin: UK.

Support: For assistance, visit livewell.honeywellhome.com.

Model Numbers: THR842D, DT92.

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