The Honeywell Home DT4 Grey Wired Room Thermostat DT40GT21 is a contemporary digital thermostat for accurate room temperature control in homes and apartments. With its slim modern design, large clear LED segment display, and energy-efficient auto-off technology, it combines style with simple, intuitive operation.

Key Features

• Energy-efficient LED display automatically turns off when not in use to conserve battery.
• Backlit captive touch buttons for easy operation in any lighting conditions.
• Integrated eco-mode provides timed temperature offset for energy savings.
• Fuzzy Logic control algorithm optimises boiler operation for precise temperature maintenance.
• Wide system compatibility including heat pumps, zoning, underfloor heating, and zone valves.
• Frost protection maintains minimum 5 °C setpoint when system is off.

Why Choose Honeywell Home DT4 Grey?

Stylish grey finish complements modern interiors while delivering proven Honeywell reliability and advanced energy-saving functions in a user-friendly package.

ErP Class IV (+2%) rating ensures compliance with current heating control efficiency regulations.

Suitable For

• Gas boilers, combi boilers, and heat pumps (24-230 V on/off control).
• Zone valve applications and multi-zone heating systems.
• New installations and thermostat replacements requiring wired controls.

Technical Specifications

• Brand: Honeywell Home by Resideo
• Model: DT4 Grey Wired Room Thermostat
• MPN: DT40GT21
• GTIN: 5059085002626
• Control Type: On/Off (24-230 V)
• Power Supply: 2 x AA batteries (included)
• Battery Life: Approx. 3.5 years
• Set Point Range: 5 °C to 35 °C
• Display Range: 0 °C to 40 °C
• Sensor: 10k NTC thermistor @ 25 °C
• Switching Capacity: 3 A resistive, 1 A inductive
• Switch Type: SPDT
• ErP Class: Class IV (+2 %)
• Dimensions: 101 x 101 x 23 mm (HxWxD)
• Weight: 105 g
• Terminal Size: Max 2.5 mm²
• Operating Temperature: 0 °C to 40 °C
• Warranty: 2 years

Installation & Operation

Simple wall-mounted wired installation featuring flip-up wiring platform. User menu configures heating/cooling modes, eco offset timing, and frost protection. Installer menu enables cycle rate adjustment, setpoint limits, and commissioning settings.