Install a smart thermostat
Save £150–300/year in 1–2 hours — no electrician needed
Most people call an electrician for this. You probably don't need to.
Last updated: March 2025
Only basic tools needed — most homes already have them.
Before you start
Smart thermostats save money by learning your schedule and adjusting heating automatically. Studies show average savings of £150–300 per year on heating bills compared to a standard thermostat.
This is a job involving low-voltage heating wiring (not mains electrical wiring). It is legal to do yourself in the UK. The risk is low if you follow the manufacturer wiring diagram carefully.
Some links on this page are affiliate links. If you buy through them we may earn a small commission at no extra cost to you.
Tools & materials
- ✓Cross-head screwdriver— for wall plate and terminals
- ✓Phone or camera— to photograph existing wiring before disconnecting
- !Smart thermostat kit— buy — Nest, Hive, Tado, or Drayton Wiser are popular UK options
Want everything in one go?
Prices shown on retailer sites. Always check current pricing before purchasing.
Check compatibility
Most UK smart thermostats (Nest, Hive, Tado, Drayton Wiser) work with standard gas combi boilers. Check the manufacturer compatibility checker with your boiler model. If you have an older system with a hot water cylinder, check whether the thermostat supports multi-zone systems.
Most people get this done in under 5 minutes.
Where beginners go wrong
Not checking compatibility first — some older boilers or system boilers need a different configuration or a professional install.
Mixing up Live and Switched Live wires — the boiler will not fire correctly. Always follow the manufacturer's UK wiring diagram, not a generic one.
Not configuring the schedule properly — the default settings are rarely optimal. Spend 10 minutes in the app setting your actual heating times.
Stop and call a heating engineer if...
Your system has more than 3 wires at the thermostat — it may be a more complex system requiring professional configuration
The boiler does not fire after installation — do not leave the heating non-functional overnight in cold weather
You have an oil boiler, heat pump, or underfloor heating system — check compatibility requirements carefully
Cost breakdown
Recommended starter kit
Five tools that cover most home repairs.
- →Adjustable spannerAmazon·Screwfix
- →Screwdriver setAmazon·Screwfix
- →PTFE tapeAmazon·Screwfix
- →Spirit levelAmazon·Screwfix
- →Tape measureAmazon·Screwfix
Want everything in one go? Get it on Amazon
What you just learned
You now understand how heating control wiring works and how to replace a thermostat. This pays for itself in energy savings within the first year and gives you full control over your heating schedule from anywhere.
Most people would pay a tradesperson for this.
⚠️ Watch out if you rent
Always get your landlord's written permission before changing a thermostat in a rented property. Keep the original thermostat to reinstall when you leave.