Honeywell Home THR840DEU DT2 Wired Thermostat

The Honeywell Home THR840DEU DT2 is a wired thermostat with a battery-powered LCD display and push-button control. Its listed features include a 5°C to 35°C set-point range, self-learning TPI control and a timed Eco setting, making it a straightforward option for compatible heating or cooling systems.

At a glance

Digital wired on/off thermostat for heating or cooling control.
The listing specifies a 5°C to 35°C set-point range and self-learning TPI control.
One-touch Eco control allows a lower set point for a timed period of 1 to 24 hours.
The listing describes an extra-large display, simple interface and installer mode.

Price

£33.99Save 35%

Reference price: ~~£52.12~~

Price checked: 12 Nov 2026

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Pros and cons

Pros

Timed Eco mode gives users a temporary lower set point without describing a weekly programming schedule.
The manufacturer says the battery is included and can be changed by unclipping the front cover.
Customer feedback reports ease of installation and use, along with positive impressions of accuracy and appearance.

Technical specifications

16 specifications

Identity
Brand	Honeywell Home
Model	THR840DEU

Display
Screen technology listed	LCD
Display	Extra-large display and simple user interface

Control and operation
Control methods listed	Touch
Temperature control	Learning
Set-point range	5°C to 35°C
Eco setting duration	from 1 hour to 24 hours in 1-hour increments

Connectivity and controls
Wireless connection listed	BACnet MS/TP

Power and battery
Power configuration	Battery Powered
Battery requirement	1 AA batteries required. (included)

Installation and dimensions
Mounting type listed	Wall Mount
Dimensions	2.9D x 9W x 9.2H centimetres
Weight	299 Grams
Colour	Wired White
Product style	Wired \| Basic

What to know before buying

Listing details to confirm

Listing details are inconsistent or unconfirmed: connectivity is presented as Wi-Fi in the product details but BACnet MS/TP in the technical fields, while the listing also describes the thermostat as wired. The controls are described as push-button and touch, and the battery-powered specification appears alongside a 230 Volts listing. Confirm the exact model configuration, wiring, system compatibility and included battery details before purchase. The separate manufacturer content discusses DT3 products, so its DT3 compatibility claims should not be assumed to apply to this THR840DEU.

What’s in the box

Included

1 thermostat

Who is it for?

A good fit for

Buyers seeking a basic wired thermostat with a display and one-touch timed Eco adjustment.
Users whose compatible heating or cooling setup suits on/off control and who value self-learning TPI operation.

Less suited to

Buyers who require app control, remote operation or confirmed Wi-Fi connectivity.
Anyone needing a confirmed fit for a particular boiler or control system without checking compatibility first.

Honeywell Home THR840DEU DT2 Wired Thermostat · photo 2 — Additional product photo 2

Customer reviews on Amazon

4.2 / 5 · 968 ratings

5 stars63%63%
4 stars17%17%
3 stars10%10%
2 stars2%2%
1 star8%8%

Customer feedback reports that the thermostat is easy to install and use, with positive comments about functionality, build quality, appearance and perceived accuracy. The feedback also flags mixed experiences with adjustability and instructions described as short on detail. For a wired thermostat with timed Eco control and a defined set-point range, the reported usability may matter, but installation guidance and system compatibility are worth considering. Overall ratings lean positive, while not establishing why individual customers rated it as they did.

Positive themes

Customers report ease of installation and use, and praise the product's functionality and quality.
Some customer feedback praises its appearance and perceived accuracy.

Negative themes

Customer feedback says the installation instructions can lack detail.

Mixed feedback

Feedback on adjustability is mixed.

Frequently asked questions

What temperature range does the listing specify?

It gives a set-point range of 5°C to 35°C.

Does it have a timed Eco setting?

The listing says the one-touch Eco button can set a lower temperature for a selected period from 1 to 24 hours in one-hour increments.

Is this thermostat Wi-Fi enabled?

The details conflict: one field lists Wi-Fi, while the technical listing gives BACnet MS/TP and describes the thermostat as wired. Confirm the actual connectivity for the selected model before buying.

Will it work with my boiler?

The listing names boilers as a use, but does not establish compatibility with every boiler. Check that the thermostat’s wiring and on/off control suit your system.