Fixington

Replace Thermostat

Trade: Heating Engineer

⭐ Introduction

A thermostat controls your heating system by regulating the temperature inside your home. Replacing a thermostat may be needed when your old one is faulty, inaccurate, or simply outdated. Newer models can offer improved energy efficiency and better control over your heating, potentially saving you money on bills.

Common reasons to replace a thermostat include:

  • It stops working or shows incorrect readings.
  • You want to upgrade to a programmable or smart thermostat.
  • You’re fitting a new heating system or upgrading your existing one.

Making sure your thermostat functions correctly helps maintain a comfortable home environment while potentially reducing energy waste.

🔧 What the job involves

Replacing a thermostat is more than just swapping one unit for another. A heating engineer will:

  • Turn off your heating system and isolate electrical supply for safety.
  • Remove the old thermostat, carefully disconnecting wiring.
  • Check that the new thermostat is compatible with your heating system.
  • Install the new thermostat and connect wiring correctly.
  • Test the system to confirm the thermostat works properly.
  • Program the thermostat if it’s digital or has smart features.
  • Provide basic instructions on how to operate the new controls.

The process can vary depending on your thermostat type (mechanical dial, digital, or smart) and heating system (boiler, electric, or underfloor heating).

📝 Step-by-step from booking to completion

  1. Enquiry: Contact a Gas Safe registered heating engineer or a reputable heating company to discuss your needs.
  2. Survey and Quote: A professional may visit to inspect your existing thermostat and heating system, then provide a written quote.
  3. Scheduling: Arrange a convenient day for the engineer to carry out the work.
  4. Day of Work: The engineer arrives, turns off your heating system, safely removes the old thermostat, and installs the replacement.
  5. Testing and Demonstration: After installation, they will test the system and show you how to use the new thermostat.
  6. Completion and Paperwork: Receive any necessary paperwork such as compliance certificates or manufacturer warranty details.
  7. Aftercare: Keep contact details handy for any future servicing or troubleshooting.

💷 Main costs to expect

  • Labour: Typically £60 to £100 per hour depending on location and engineer’s experience.
  • Thermostat Unit: Basic models from around £25; programmable or smart thermostats from £80 to £200+.
  • Materials: Wiring clips, back plates, and any necessary electrical fittings, usually under £20.
  • Disposal: Removing and disposing of old equipment may cost around £10–£20.
  • Certification: Generally no formal certification required unless the thermostat is part of a new heating installation, but any associated gas appliance work must be Gas Safe registered.

Example itemisation:

  • Labour (1.5 hours): £90
  • Thermostat: £120 (programmable)
  • Materials: £15
  • Disposal: £15
    Total: £240 (excluding VAT)

📊 What affects the price

  • Access: Difficulty reaching the current thermostat or rewiring challenges.
  • Complexity: Installation of smart or touchscreen models may take longer.
  • Regulations: Additional costs if work involves gas system alterations or electrical upgrades that require certification.
  • Remedial works: Repairing damaged wiring or wall plastering after removal.
  • Location: Prices tend to be higher in London and the South East.
  • Timeline: Urgent or same-day jobs might incur premium charges.

⏱ How long does it take?

  • Straight swap: 45 minutes to 1.5 hours for a simple replacement of a like-for-like thermostat.
  • Complex install: 2 to 3 hours if installing a new programmable or smart model requiring extra wiring or system integration.
  • Additional work: Longer if other heating system upgrades are needed simultaneously.

🏠 Can you DIY it?

While changing the thermostat might seem straightforward, it involves working with electrical components and potentially your heating system controls. If you’re not confident or qualified, it’s safer to hire a Gas Safe registered engineer or a qualified heating electrician.

Key reasons to avoid DIY include:

  • Risk of electrical shock or damage if wiring is handled incorrectly.
  • Possible voiding of your boiler warranty or home insurance if improper installation causes faults.
  • Compliance with UK safety standards, including Part P Building Regulations that apply to electrical work in homes.
  • Need to maintain gas safety and heating system integrity.

If you choose to install a thermostat yourself, ensure the mains power is off and follow manufacturer instructions carefully.

💰 Typical UK price range

Replacing a thermostat typically costs between £150 and £350 including parts and labour, excluding VAT if applicable. Basic mechanical models with straightforward fitting are at the lower end, while smart thermostats or complex system upgrades are at the higher end.

Remember that VAT at 20% applies to most domestic services provided by VAT-registered businesses.

✅ Handy tips before you start

  • Prepare: Make a note of your current thermostat model and system type when enquiring.
  • Clear the area: Ensure easy access to the thermostat and power supply.
  • Ask for written quotes: Comparing prices and including all work helps avoid surprises.
  • Keep documentation: Save receipts, warranties, and manuals for future use.
  • Consider upgrades: Newer thermostats often offer better energy-saving features; discuss options with your engineer.
  • Regular servicing: Have your heating system and thermostat checked annually to maintain efficiency.
  • Understand your controls: Ask the engineer to explain programming and maintenance to avoid issues later.

By planning ahead and relying on professional assistance, replacing your thermostat can be a smooth, safe, and rewarding home improvement.