Honeywell Home THR842D Wireless Room Thermostat

Introduction

The THR842D is a wireless room thermostat designed for efficient home climate control. It communicates wirelessly with a Relay Box using an 868MHz Radio Frequency (RF) band to manage heating system components like boilers, pumps, or zone valves. The system offers two-way RF communication for high-performance, energy-efficient control, boiler information display, and easy setup. It also features an ECO energy-saving mode.

Operating Indicators

The thermostat displays various indicators to show its current status:

Note: Frost protection is not available in cooling operation.

ECO Energy Saving Feature

The ECO feature allows for timed periods of energy saving at a predefined lower temperature (e.g., 18°C). Pressing the green ECO button activates this mode for a set duration. The display will show a countdown of the remaining ECO time.

To exit ECO mode before the timer expires, press the ECO button again. You can also temporarily adjust the ECO temperature by pressing the + or - buttons.

Installation

General Notes:

• For optimal performance, install the thermostat and Relay Box in an open space, at least 30cm away from metal objects and 1 meter from other electrical equipment.
• Do not mount the Relay Box on metal wall boxes.
• Ensure AC mains supply/load cables are kept separate from signal wiring for EMC compliance. Refer to EN61000-5-1 and -2 standards.
• The THR842D Room Thermostat is battery-powered.
• The Relay Box requires a permanent 230V~ supply.
• Install the Relay Box before installing the Room Thermostat.
• The RF link between the thermostat and Relay Box is pre-configured from the factory. If components are separated or mixed, a binding procedure (refer to Section 6) is required.

Relay Box Installation

The Relay Box connects to the 230V~ 50-60Hz power supply and the heating system components. Ensure correct wiring to terminals A-B and A-C as per the diagram. Wire gauges of 1.5-2.5mm² are recommended, with a maximum cable entry of 6mm. The diagram shows typical connections for a boiler (NILT1T2) or other systems (V4043H).

Room Thermostat Installation

The THR842D Room Thermostat can be mounted on a wall using the backplate or placed on an optional table stand. Ensure it is located in an open space where it can accurately sense room temperature and where the RF signal strength is high. Test the signal strength before final installation.

Signal Strength Test: The thermostat display shows signal strength levels (0-5). A strong signal (3-5) allows proceeding with mounting. A weak signal (0-2) requires repositioning the thermostat.

Operation

Automatic Operation

In automatic mode, the thermostat controls the heating system based on programmed settings. The green LED on the thermostat indicates the relay status:

• Green LED ON: Relay is connected (heating active).
• Green LED OFF: Relay is disconnected (heating inactive).

Temporary Manual Override

Pressing the button on the thermostat temporarily overrides the current relay position. This allows for manual control for a short period.

Loss of RF Communications

If RF communication is lost for an extended period (e.g., over 1 hour), the red LED on the thermostat will light up. The Relay Box will then operate in a failsafe mode, as configured by the installer.

Installer Mode

Installer Mode allows for advanced configuration and parameter adjustments. To enter Installer Mode, follow the specific button press sequence indicated in the manual (e.g., pressing - and + simultaneously for 5 seconds).

Parameter Selection and Adjustment

Within Installer Mode, you can select and change various parameters. The display will show the current parameter and its value. Use the + and - buttons to navigate through parameters and adjust their settings.

Parameter Table: A detailed list of parameters, their descriptions, range of values, and default settings is provided in the manual.

Binding/Rebinding Procedure

Binding is required when system components are replaced or if the Relay Box has incorrect or no binding data stored. This ensures the thermostat and Relay Box can communicate.

Binding Relay Box

To put the Relay Box into binding mode, press and hold the button for 15 seconds until the LED flashes. Refer to the manual for specific LED patterns.

Binding Room Thermostat

To put the Room Thermostat into binding mode, press and hold the button for 5 seconds. The display will show the binding status.

Connecting Components

Once both devices are in binding mode, they will automatically connect. The green LED on the thermostat will indicate successful connection.

Resetting Data

Stored data in the Relay Box or Room Thermostat can be reset to factory defaults following the procedures outlined in the manual.

Support

For assistance with this product, please visit livewell.honeywellhome.com.

Manufacturer: bk-electronic GmbH, Hardhofweg 40, 74821 Mosbach, Germany.

Country of origin: UK.

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