The THR840 is a digital room thermostat that is more accurate than a mechanical room thermostat.

Measurements from an electronic sensor are compared with your desired temperature and advanced control software is used to maintain the temperature in an energy efficient manner.

  • System Control – heating and cooling functions from 5°C to 35°C
  • Easy to Use – extra large LCD display with large text
  • Precise Temperature Control – typically accurate to within 0.5°C for maximum comfort
  • Ideal for Combi-Boilers – two wire, volt free output connections
  • Easy to install – Simply fix it directly to the wall


Buy now

Our heating products are stocked in many home and DIY outlets across the UK.
Alternatively you can buy this product directly from the following websites.


Honeywell Home Heating

We have a range of heating controls designed to improve the efficiency of your home heating

Easy To Install and easy to use

Honeywell Home’s heating products have a great range of features that will allow you to control your heating more efficiently and help save you energy and money. All this is backed up by our 2 year product guarantee.

Instruction Manual