Boiler Replacement and New Boiler Installation in London

All of our Gas Safe boiler engineers are experienced fitters of new boilers in London properties.

Replacing a boiler requires an initial survey visit before a quote can be prepared.

4.9 stars, 1,000+ reviews | Gas Safe Registered | Survey and Fixed Quote | Same or Next Day Survey Available | Mon to Sat 8am to 5pm | Book Online 24/7

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Specific arrival times. We confirm a one-hour arrival window on every booking, so there is no waiting in all day.

How much does it cost to replace a boiler in London?

A replacement gas boiler in London costs on average £2,500 to £4,500 supplied and fitted, depending on the boiler, the make, and how much work the installation needs, and the job starts with a survey visit costing £35+VAT that is deducted from the final invoice if you go ahead. The reason we survey first rather than quote a flat price online is that the real cost is driven by what an online form cannot see: the route and length of the new flue, whether the existing gas supply pipe is large enough for a modern boiler or needs upsizing, where the condensate can safely run, and whether the system needs a flush or filter before a new boiler is connected.

• £35 + VAT survey and quote visit, deducted from the final invoice if you proceed
• Supply and fit of a replacement gas boiler, on average £2,500 to £4,500
• A fixed written quote before any installation work is booked
• No obligation to proceed after the survey

A worked example: a straightforward combi-for-combi swap in the same location, where the flue and pipework stay put, sits at the lower end of the range, while converting a conventional boiler with a tank and cylinder to a combi, or moving the boiler, sits higher because of the extra pipework, the flue and the system changes. The survey is what tells us which of those your job is, so the quote you accept is the price you pay.

Ready to book a survey?

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Why London chooses Silver Saints for a new boiler

Here is why London customers have booked Silver Saints for boiler replacement and new boiler installation.

• 4.9 stars from over 1,000 Google reviews
• 5 stars on Trustpilot and Checkatrade
• Gas Safe registered engineers, with the installation notified to Gas Safe and Building Control
• £5 million public liability insurance
• Operating across London since May 2008
• All work guaranteed against faulty workmanship, with a 12-month guarantee on labour, plus the manufacturer's warranty on the boiler
• A fixed written quote after survey, with the £35+VAT survey fee deducted if you proceed

Ready to book? We can usually survey today or tomorrow, subject to availability.

Call 0207 0999 199 Book Online Now

Why do you survey before quoting for a new boiler?

Silver Saints survey before quoting because the cost and the safety of a boiler replacement depend on details only a Gas Safe engineer can confirm on site, and an online fixed price has to guess at them. On the survey we check the gas supply pipe size, because many older London properties have a 15mm or undersized run that will not feed a modern boiler at full rate and has to be upsized to 22mm. We work out the flue route and termination, which is rarely simple in a flat or a mid-terrace, the condensate route and whether it needs a pumped or internal solution to avoid freezing, and the state of the existing system, because connecting a new boiler to a sludged-up system without a flush and a filter voids most manufacturer warranties. We also confirm the boiler can be sited and serviced safely. Quoting from a photo skips all of that, which is how online quotes become more expensive on the day.

Replacing a back boiler or converting to a combi in London

Silver Saints replace back boilers and convert conventional systems to combis across London, which is one of the most common upgrades in the city's older housing stock. A back boiler sited behind a gas fire is now obsolete and was discontinued, so it is replaced with a modern wall-hung boiler, which frees the chimney breast and the airing cupboard but means new flue, pipework and a condensate route. Converting a conventional boiler with a cold tank in the loft and a hot cylinder to a combi removes the tank and cylinder and runs everything from one wall-hung unit, which suits a smaller flat but needs the mains flow and pressure checked first, because a combi is only as good as the cold mains feeding it. Whether a combi or a system boiler is right for you depends on how many bathrooms run at once, which we assess on the survey.

Boiler replacement across London property types

The right boiler and the work involved track London building stock. In Victorian and Edwardian terraces and conversions across Wandsworth, Hackney, Islington and Camden we often find back boilers, airing-cupboard system boilers and undersized gas runs, so the job is as much about pipework and flue as the boiler itself. In period mansion blocks across Kensington, Chelsea and Marylebone the flue, the boiler position and freeholder or managing-agent consent matter, and a communal arrangement can dictate what is allowed. In modern new-build flats around Nine Elms, Battersea and Canary Wharf the boiler is usually a combi in a utility cupboard with a defined flue route, where the constraint is access and the building's own rules. We confirm all of this on the survey before quoting.

Combine a boiler replacement with related heating work

Because a Silver Saint is multi-trade and Gas Safe registered, a boiler replacement is the right moment to deal with related heating work in the same project rather than as separate call-outs. A new boiler should be protected by a clean system, so it pairs naturally with a central heating power flush and an inhibitor and filter before the boiler is connected. If your existing boiler is not beyond economical repair, a gas boiler repair may be the better first step, and once a new boiler is in we keep it covered with an annual gas boiler service and, for landlords, a gas safety certificate. Tell us everything on the survey so the quote covers the lot.

Boiler Replacement in London FAQs

Can you survey for a new boiler today in London?

Silver Saints usually offer same-day or next-day survey appointments for boiler replacement across London, subject to availability, and you can call 0207 0999 199 or book online to arrange the £35+VAT survey visit.

How much does it cost to replace a boiler in London?

A replacement gas boiler in London costs on average £2,500 to £4,500 supplied and fitted depending on the boiler and the work, and the job begins with a £35+VAT survey that is deducted from the final invoice if you proceed.

Why do I need a survey before getting a boiler replacement quote?

A survey is needed because the real cost of a boiler replacement depends on the flue route, the gas supply pipe size, the condensate run and the state of the existing system, none of which can be judged accurately from an online form, so a Gas Safe engineer checks them on site before quoting.

Is a new boiler installation notifiable work?

Yes, replacing a gas boiler is notifiable Building Regulations work, so Silver Saints notify the installation to Gas Safe and Building Control, complete the Benchmark commissioning record, and register the manufacturer's warranty.

Can you replace a back boiler or convert me to a combi?

Silver Saints replace obsolete back boilers with modern wall-hung boilers and convert conventional tank-and-cylinder systems to combis across London, confirming the mains flow and pressure on the survey so the new combi performs correctly.

Do you fit the boiler or do I buy it separately?

Silver Saints supply and fit the replacement boiler as one job, recommending the right make and model for the property on the survey, which keeps the manufacturer's warranty and the installation with a single accountable Gas Safe installer.

Which London areas do you cover for boiler replacement?

Silver Saints cover every London borough for boiler replacement and new boiler installation, including Westminster, Kensington and Chelsea, Camden, Islington, Wandsworth and Hackney, plus the surrounding TW, KT, CR and BR postcode areas.

Is the work guaranteed and insured?

All boiler replacement work by Silver Saints is insured with £5 million public liability cover and carries a 12-month guarantee on labour, alongside the boiler manufacturer's own warranty registered on installation.

Customer Reviews

Read what our customers say about our Silver Service on the UK's leading review platforms.

• Google Customer Reviews
• Trustpilot Customer Reviews
• Checkatrade Customer Reviews
• Yell Customer Reviews

Boiler replacement in London, in short

Silver Saints supply and fit replacement gas boilers across every London borough, with Gas Safe registered engineers surveying, quoting and installing combi, system and conventional boilers, including back-boiler replacements and conventional-to-combi conversions, with the work notified to Gas Safe and Building Control and commissioned on a Benchmark record. The job starts with a £35+VAT survey visit, deducted from the final invoice if you proceed, that confirms the flue route, gas supply pipe size, condensate run and system condition so the fixed quote reflects the real property, and a replacement boiler supplied and fitted costs on average £2,500 to £4,500 depending on the boiler and the work. The service covers flats and houses across Victorian and Edwardian terraces, mansion blocks, concrete builds and modern new builds plus the TW, KT, CR and BR areas, runs Monday to Saturday from 8am to 5pm with survey and next-day appointments usually available, and the team holds a 4.9-star rating from over 1,000 Google reviews. To book a survey, call 0207 0999 199 or use https://bookings.silversaints.com.

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