Honeywell Home THR840D Digital Room Thermostat: User Guide & Installation with ECO

Product Overview

The Honeywell Home THR840D is a digital room thermostat designed to provide efficient and comfortable temperature control for your home. It features an ECO energy saving function to help reduce energy consumption.

Key Features

ECO Energy Saving Feature: Pressing the green ECO button activates a timed period with a different, predefined temperature (typically 18°C) to save energy. The duration of this ECO period can be set from 1 to 24 hours. The display shows a countdown of the remaining ECO time. Users can temporarily adjust the ECO temperature by pressing the up or down arrow buttons (represented as ▲ or ▼). To exit the ECO mode, press the ECO button again.
Temperature Control: Displays the current room temperature and allows users to set and adjust the desired temperature.
Heating/Cooling: Supports both heating and cooling systems, indicated by a changeover indicator.
Frost Protection: Provides protection against freezing temperatures, though this feature is not available during cooling operation.
Low Battery Indicator: Alerts the user when the batteries need to be replaced (uses 2 x LR6 AA Alkaline batteries).
Fault Indicator: Signals any system errors or malfunctions.

Operating Indicators

[Heating Demand Indicator]: Shows when the thermostat is calling for heat or cooling.
[Frost Protection Indicator]: Indicates that the frost protection function is active.
[Low Battery Indicator]: Appears when the batteries are low and need replacement.
[Fault Indicator]: Appears when there is an error with the thermostat or system.

Installation

The THR840D thermostat is typically mounted at a height of 1.2 meters from the floor. Installation involves wiring the thermostat to the heating/cooling system. The thermostat connects to a 24-230V AC supply and has an 8(3)A rating. Key connections include:

L: Live connection
N: Neutral connection
ABC terminals: For connecting the heating/cooling system (specific function depends on system type).

The installation process involves mounting the backplate, connecting the wires, and attaching the thermostat unit. Specific wiring diagrams are provided in the original documentation for different system configurations.

[Diagram description: Shows the thermostat backplate being mounted to a wall, with wires being connected to terminals labeled L, N, and ABC. Another diagram shows the thermostat unit clipping onto the backplate.]

Installer Mode and Parameters

The thermostat features an Installer Mode, which allows for advanced configuration and parameter adjustments. This mode is accessed through a specific sequence of button presses.

Within Installer Mode, users can select and change various parameters that control the thermostat's operation. The following table summarizes key parameters:

Parameter	Description	Range of values	Default
Minimum ON/OFF time (Ot)	Minimum time the system is switched on or off.	1, 2, 3, 4, 5 min	1 min
Cycle rate (Cr)	Number of cycles per hour.	{3, 6, 9, 12}	6
Proportional band width (Pb)	Controls the sensitivity of temperature regulation.	1.5 ... 3.0 K	1.5 K
Temperature measurement offset (tO)	Adjusts for sensor inaccuracies.	-3 ... 3 K	0 K
Upper setpoint limit (uL)	Maximum settable temperature.	21 ... 35 °C	35 °C
Lower setpoint limit (LL)	Minimum settable temperature.	5 ... 21 °C	5 °C
ECO temperature (ES)	The predefined temperature for ECO mode.	5 ... 35 °C	18 °C
Heat/cool changeover (HC)	Configures the system for heating or cooling. 0 = Disable, 1 = Enable.	0, 1	0
Off setpoint adjust (OS)	Setpoint adjustment when the thermostat is off (frost protection).	-- (= Off), 5...16°C	5°C
Electric heat (EH)	Enables electric heating. 0 (<3A) / 1 (3A-8A).	0 (<3A) / 1 (3A-8A)	0 (<3A)
Reset parameters (FS)	Resets all parameters to factory defaults. 0/1.	0/1	1 (factory)

[Diagram description: A flowchart illustrating how to navigate installer mode, select parameters, change values, and exit the mode.]

Support and Further Information

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

Manufactured by Resideo Technologies Inc. The Honeywell Home trademark is used under license from Honeywell International Inc.

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Honeywell Home THR840D Digital Room Thermostat