Average cost
Most UK homeowners pay between £2,000 and £4,200 for a full boiler replacement, including the new unit and installation labour. A straightforward like-for-like combi swap sits at the lower end; moving boiler location or upgrading system type pushes costs higher.
Cost breakdown
Roughly a third of the total is the boiler unit itself, with the remainder split between installation labour and small parts — flue, filters, and controls. Premium A-rated combi boilers from established manufacturers command a higher unit price but typically carry longer warranties.
Factors affecting price
Boiler type
Combi boilers are generally the cheapest to install where one is already fitted. System and regular (heat-only) boilers cost more where a cylinder needs replacing or relocating.
Property type
Flats and terraced houses with straightforward pipe runs are typically quicker and cheaper to work on than larger detached properties with longer runs to radiators.
Regional differences
London and the South East typically run 20–30% above the national average due to higher labour rates; the North of England and Wales tend to sit below it.
How to save money
- Get at least three quotes from Gas Safe registered engineers
- Book outside of the September–November peak season if your existing boiler isn't an emergency replacement
- Ask about manufacturer cashback or extended warranty promotions
When to hire a professional
Boiler work must legally be carried out by a Gas Safe registered engineer in the UK — never attempt any gas work yourself.
FAQ
How long does a boiler replacement take?
A straightforward like-for-like swap usually takes one working day. Moving the boiler or upgrading the system can take two to three days.
Do I need a Gas Safe engineer?
Yes — it is a legal requirement in the UK for any boiler or gas appliance work.