The Honeywell Home DT4R Wireless Room Thermostat and Receiver (YT42WRFT20) is a battery-powered heating control solution designed to provide convenient wireless room temperature regulation. Supplied with a mains-powered relay receiver, this complete thermostat pack allows the thermostat to be positioned in a suitable location without requiring a direct thermostat cable connection to the boiler or heat source.
Operating on an encrypted 868 MHz radio frequency, the DT4R provides on/off heating control for compatible boilers, heat pumps and zone valves. Its large LED segment display, adjustable brightness, fuzzy logic control and adjustable Eco Offset make it a practical choice for domestic heating installations.
With a temperature set-point range of 5°C to 35°C, built-in frost protection and compatibility with the Honeywell Home BDR91A relay box, the DT4R is suitable for new installations and selected existing wireless heating control upgrades.
Wireless 868 MHz On/Off Control White Finish 5-Year Warranty 2 × AA Batteries
Key Features
1. Complete Wireless Thermostat and Receiver Pack
Supplied with a DT4R wireless room thermostat and a 230V AC mains-powered relay receiver. The receiver connects to the heating appliance, while the thermostat communicates wirelessly, reducing the need for a thermostat cable between the two locations.
2. Encrypted 868 MHz Wireless Communication
Uses an encrypted 868.0–868.6 MHz radio frequency with a typical indoor communication range of up to 30 metres in a residential building environment.
3. Fuzzy Logic On/Off Temperature Control
Features fuzzy logic control with selectable cycle rates and installer-adjustable minimum on/off times. It provides on/off demand switching for compatible heating appliances operating with a 24–230V AC control circuit.
4. Clear LED Display and Adjustable Brightness
The large LED segment display features adjustable brightness and status indicators for heating, cooling, wireless signal, Eco mode, off mode, low battery and warnings. The display switches off when not in use and can be activated using the wake-up button.
5. Eco Offset and Built-In Frost Protection
Provides a timed Eco Offset adjustment from -3°C to +3°C in 0.5°C steps, with a duration of 1–24 hours. The Off position maintains a 5°C frost-protection minimum to help protect the heating system against freezing conditions.
6. Flexible Installation and 5-Year Warranty
The thermostat supports table-stand or wall-mounted installation, while the receiver can be mounted directly onto a wall or wall box. The product carries a 5-year manufacturer warranty according to the supplied specifications.
Additional Installer Features
- Flip-up receiver wiring platform for easier wiring access.
- Receiver status LED, manual override and reset buttons.
- Installer settings for cycle rate, minimum on/off time and set-point limits.
- Configurable heating, cooling or heating and cooling operation.
- Installer-configurable heat/cool changeover.
- Binding and factory reset options.
- Failsafe operation: if the sensor or radio link is lost, the receiver cycles demand at 20% on and 80% off.
What's Included in the Box?
- Honeywell Home DT4R white wireless room thermostat.
- Wireless relay receiver (230V AC mains powered).
- 2 × AA alkaline batteries for the thermostat.
- Wiring plate and mounting fittings.
- Installation literature in 14 languages, including English.
Technical Specifications
General Information
| Manufacturer |
Resideo (Honeywell Home) |
| Model |
DT4R |
| Manufacturer Stock Code |
YT42WRFT20 |
| EAN |
5059085002640 |
| Colour |
White |
| Control Type |
On/off, fuzzy logic |
| Operating Modes |
Heating, cooling and off |
| Warranty |
5 years |
Thermostat Specifications
| Power Supply |
2 × AA alkaline batteries |
| Battery Life |
Up to 1.5 years |
| Temperature Sensor |
10 kΩ at 25°C NTC thermistor |
| Set-Point Range |
5°C to 35°C |
| Room Temperature Display Range |
0°C to 40°C |
| Frost Protection |
5°C minimum |
| Eco Offset |
-3°C to +3°C in 0.5°C steps, 1–24 hours |
| Display |
LED segment display with adjustable brightness |
| Dimensions (H × W × D) |
101 × 101 × 54mm |
| Weight |
130g |
Wireless Communication
| RF Frequency |
ISM 868.0–868.6 MHz |
| Maximum RF Power |
25mW |
| Protocol |
Encrypted |
| Communication Range |
Up to 30m indoors in a residential environment |
Relay Receiver Specifications
| Power Supply |
230V AC mains |
| Switched Appliance Voltage |
24–230V AC |
| Electrical Rating |
5A resistive / 3A inductive |
| Switch Type |
SPDT |
| Terminals |
Up to 2.5mm² cable |
| Ingress Protection |
IP30 |
| Weight |
200g |
Environmental and Compliance Information
| Operating Temperature |
0°C to 40°C |
| Storage Temperature |
-20°C to 55°C |
| Relative Humidity |
10–90%, non-condensing |
| ErP Class |
Class IV (+2%) |
| Approvals Listed |
EMC 2014/30/EU, LVD 2014/35/EU, R&TTE 1995/5/EC |
Heating System Compatibility
| Application |
Compatibility |
Notes |
| Gas combi, system and heat-only boilers |
Yes |
Must accept a 24–230V AC on/off thermostat circuit. |
| Heat pumps |
Yes |
Must accept a simple on/off demand input. |
| 2-port zone valves |
Yes |
On/off demand control through the receiver. |
| Solid fuel boilers |
Yes |
Must accept an external thermostat input. |
| Underfloor heating zone control |
Yes |
On/off zone control for suitable heating and cooling applications. |
| Honeywell Home BDR91A relay box |
Yes |
Compatible; sold separately. |
| evohome / HCC100 zoning |
Check first |
Confirm the correct product and integration requirements before ordering. |
| OpenTherm modulation |
No |
This is an on/off model. Consider the YT43MRF series for OpenTherm. |
| Direct 240V electric heating |
No |
Not supported by the manufacturer for this model. |
Important Compatibility Information
On/off control only: The YT42WRFT20 does not provide OpenTherm modulation. For compatible OpenTherm control, refer to the Honeywell Home YT43MRF modulating series.
evohome and HCC100: The supplied compatibility information identifies the BDR91A relay box as compatible with this pack. It lists evohome, HCC100, HCE80, HCC80 and ST9000 against the separate DTS42WRFST20 spare thermostat. Contact the supplier to confirm the correct product before ordering for these systems.
Time control: This thermostat does not include a built-in time schedule or programmer. Separate time control may be required depending on the heating system.
Electric heating: Not suitable for direct 240V electric heating. The receiver is rated at 5A resistive and 3A inductive, and is not intended to switch a direct electric heater load.
Other DT4R Range Options
| Colour / Version |
Part Code |
Type |
| White (this product) |
YT42WRFT20 |
On/off wireless pack |
| Grey |
YT42GRFT21 |
On/off wireless pack |
| Black |
YT42BRFT22 |
On/off wireless pack |
| White modulating |
YT43MRFWT30 |
OpenTherm wireless pack |
| Grey modulating |
YT43MRFGT31 |
OpenTherm wireless pack |
| Black modulating |
YT43MRFBT32 |
OpenTherm wireless pack |
| White spare thermostat |
DTS42WRFST20 |
Thermostat only, no receiver |
Frequently Asked Questions
1. Does the Honeywell Home DT4R YT42WRFT20 come with a receiver?
Yes. The pack includes a wireless room thermostat and a 230V AC mains-powered relay receiver, along with two AA batteries and mounting fittings.
2. Can I use the DT4R with a heat pump?
Yes, provided the heat pump accepts a simple 24–230V AC on/off demand input. Cooling mode is also available for suitable appliances.
3. Will it work with evohome or an HCC100 controller?
Compatibility should be checked before ordering. The supplied manufacturer comparison information identifies the BDR91A relay box as compatible with this pack, while several zoning systems are listed against the separate DTS42WRFST20 thermostat.
4. Can I upgrade an existing Honeywell Home wireless system?
Yes. The DT4R is backwards compatible with compatible Honeywell Home RF products, including the BDR91A relay box. The thermostat can be bound to a compatible receiver using the installer menu.
5. What happens if the battery or wireless signal fails?
The thermostat displays a low-battery warning. If the sensor or radio link is lost, the receiver uses the specified failsafe operation, cycling demand at 20% on and 80% off.
6. Does the DT4R have a built-in timer or programmer?
No. The YT42WRFT20 does not include a built-in time schedule. Separate time control may be needed for installations requiring programmed heating periods.
7. Is this thermostat suitable for direct electric heating?
No. The manufacturer states that this model is not suitable for direct 240V electric heating. Its receiver is designed for compatible control circuits rather than direct electric heater loads.
8. Are other colours available?
Yes. The supplied range information lists grey and black on/off versions, as well as white, grey and black OpenTherm modulating versions. These have different manufacturer part codes.
Installation and Safety Information
The relay receiver is powered by 230V AC mains and switches compatible appliance control circuits. Isolate the electrical supply before wiring or carrying out installation work. Boiler and heat pump controls must be installed by a competent person, with gas appliance work carried out by a Gas Safe registered engineer where required. Follow BS 7671, the appliance manufacturer's instructions and applicable UK regulations.
Order Honeywell Home DT4R Wireless Thermostat from GetPlumb
Choose the Honeywell Home DT4R YT42WRFT20 for wireless on/off heating control. Supplied with a mains-powered receiver, AA batteries and mounting fittings, it offers flexible control for compatible boilers, heat pumps and heating zones.
Order now from GetPlumb.
