
Honeywell Home DT4 Grey Wired Room Thermostat
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.
Original: $51.29
-65%$51.29
$17.95More Images


Honeywell Home DT4 Grey Wired Room Thermostat
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.
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Product Information
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Description
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.





















