How much does a new boiler cost in the UK?
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A new combi boiler supply and installation costs £1,500–£3,000 for a mid-range unit (Worcester Bosch, Vaillant, Ideal). Budget £2,000–£2,500 as a realistic midpoint for most homes. Prices in London and the South East are typically 20–30% higher.
System boilers (which use a hot water cylinder) cost slightly more — £2,000–£3,500 installed. Heat-only (regular/conventional) boilers for older systems with a header tank cost similar. Budget extra if the cylinder needs replacing too.
The brand matters. Worcester Bosch and Vaillant carry a premium but offer long manufacturer warranties (up to 12 years on some models). Ideal and Baxi are good value mid-range options. Budget brands like Glow-worm cost less upfront but parts can be harder to source.
Additional costs to factor in: flue extension (£50–£150), magnetic system filter fitting (£80–£150 if not included), power flush if the old system has sludge (£400–£800), new programmer/thermostat (£100–£300 for a smart thermostat), and scaffolding if the flue exits through the roof.
Always get three quotes. A quote that seems very low often means the engineer is cutting corners — no system flush, cheap unbranded parts, or a boiler that is the wrong size for your home. Ask each engineer to confirm the boiler output (kW) and why they recommend that size.
Check the engineer is Gas Safe registered (verify at gassaferegister.co.uk) and that the boiler comes with a manufacturer warranty — most require an annual service to keep the warranty valid. A reputable installer will register the warranty for you.
The Boiler Upgrade Scheme (BUS) offers grants for switching from a gas boiler to a heat pump (£7,500 for air source). If your home has solid walls or poor insulation, investigate whether a heat pump is viable before committing to another gas boiler.
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Frequently asked questions
Does a new boiler reduce my energy bills?
Yes — replacing a G-rated boiler (pre-2005) with an A-rated condensing boiler can reduce gas consumption by 20–30%. Exact savings depend on your home, usage, and current gas prices.
How long does a boiler installation take?
A straightforward like-for-like combi replacement takes one day. If pipework changes, cylinder removal, or a power flush are needed, allow two days.