A new boiler is one of the bigger home costs you'll face — so it pays to know what's fair before you get quotes. Here's what a boiler replacement actually costs in Paisley and Renfrewshire in 2026, and what pushes the price up or down.
The short answer
A new combi boiler in Paisley typically costs £1,800–£3,500 supplied and fitted. A system or conventional boiler (for homes with a hot water cylinder) usually lands £2,200–£4,000.
The boiler unit itself is often only 40–50% of the price — the rest is the installation, any system upgrades, and the warranty-backed labour of a Gas Safe engineer.
What affects the price
Boiler make and output: premium brands (Worcester Bosch, Vaillant) cost more but come with longer warranties. A bigger home with more bathrooms needs a higher-output boiler.
Like-for-like vs relocating: swapping a combi for a combi in the same spot is the cheapest job (often a day). Moving the boiler, converting from a system to a combi, or upgrading pipework adds cost and time.
Extras: a power flush, new radiators, a smart thermostat or a magnetic filter all add to the quote — but often save money long term.
How to get an honest quote
Always get more than one quote, and make sure every engineer is Gas Safe registered — it's a legal requirement for gas work. On TrustVault, every boiler engineer is Gas Safe checked and insured before they can quote.
Be wary of a quote that's far cheaper than the rest — it often means a cheaper boiler, a shorter warranty, or corners cut on the install.
Frequently asked
How long does a boiler installation take?
A like-for-like combi swap is usually done in a day. Moving the boiler or converting the system can take 2–3 days.
Is it worth paying more for a better boiler?
Often yes — premium boilers come with 7–10 year warranties and better efficiency, which usually outweighs the higher upfront cost over the boiler's life.