New Boiler Installation Cost London 2026: Full Price Guide
A new boiler in London costs £1,500–£3,500 installed. This 2026 guide covers what affects the price, combi vs system choices, grants available, and what to watch out for.
A new combi boiler in London costs £1,500–£2,500 installed (boiler + labour). A system boiler with cylinder costs £2,200–£3,500. Prices vary by brand, boiler output, and pipework changes needed. ECO4 grant may cover full cost for eligible households.
Key Takeaways
- A combi boiler installed in London typically costs £1,500–£2,500 all in; system boilers with a cylinder run £2,200–£3,500.
- Like-for-like replacements are cheapest — moving the boiler or upgrading pipework adds £300–£800 to the bill.
- The ECO4 scheme can fund a full free boiler replacement for households on qualifying benefits.
- Always use a Gas Safe registered engineer and ensure you receive a Benchmark commissioning record on completion.
Boiler Replacement Costs in London 2026
The boiler replacement cost in London sits higher than the national average — partly because of London labour rates and partly because older housing stock, Victorian terraced houses in particular, often needs additional work before a modern boiler can be fitted cleanly. Based on jobs completed across London boroughs in 2025–2026, here is what you can realistically expect to pay. For a broader comparison of London plumber and heating costs across all job types, see our 2026 London plumber prices guide.
| Boiler Type | Unit Cost | Labour | Total Installed |
|---|---|---|---|
| Combi boiler (budget brand) | £700–£950 | £350–£500 | £1,050–£1,450 |
| Combi boiler (mid-range) | £900–£1,300 | £350–£600 | £1,250–£1,900 |
| Combi boiler (premium) | £1,200–£1,800 | £400–£700 | £1,600–£2,500 |
| System boiler + cylinder | £1,200–£2,000 | £500–£800 | £1,700–£2,800 |
| Regular (heat-only) boiler + cylinder | £1,000–£1,800 | £600–£900 | £1,600–£2,700 |
These figures cover supply, installation, flue, and Gas Safe certification. They assume a straightforward like-for-like swap in the same location. Additional costs — such as moving the boiler to a new position, replacing a header tank, or fitting a magnetic system filter — are covered in the next section.
If you are weighing up whether a repair might be cheaper than a full replacement, read our guide on boiler repair in London first. A boiler under seven years old with a single fault is often worth repairing; one over twelve years with recurring issues generally is not.
What Affects the Boiler Replacement Cost in London
Two homeowners on the same street can receive quotes that differ by £800 or more. The variation is almost always explained by a handful of factors that any reputable engineer will walk you through before they start.
Boiler brand and output rating. A 24kW Ideal Logic costs a fraction of a 35kW Worcester Bosch 8000 Life. For a typical two-bedroom London flat, a 24–28kW combi is sufficient. Larger Victorian terraces with multiple bathrooms often need 30–35kW. Oversizing wastes money on both the unit and running costs.
Location of the existing boiler. Moving a boiler — from an airing cupboard to an outside wall, or from a kitchen to a utility room — means extending gas pipe, flue, and possibly the central heating flow and return. Budget £300–£600 for a relocation within the same room, and £500–£900 for a move to a different room.
System condition and extras. Many London homes have older heating systems with sludge build-up in the radiators. Fitting a new boiler onto a dirty system shortens its life and can void the warranty. A power flush costs £300–£500 and is often recommended — or required — by the manufacturer. A magnetic system filter (Magnaclean or similar) should be fitted as standard and adds around £80–£120. Some installers include this in the quoted price; many do not, so always ask.
Flue type and routing. Most modern combis use a concentric horizontal flue through an external wall. If your boiler is on an internal wall, or if the flue needs to extend more than a metre or so, additional flue extensions add £50–£200. Vertical flues or specialist flues for high-rise London flats can cost more.
Pipework and gas supply. Older London properties — especially pre-war terraced houses in areas like Hackney, Lewisham, or Ealing — sometimes have 15mm gas supply pipes that are undersized for a modern boiler. Upgrading the gas supply pipe to 22mm adds £150–£400 depending on the run length.
Combi vs System Boiler: Which Costs Less in London?
The boiler type you choose has a significant impact on the overall boiler replacement cost in London. Combi boilers are cheaper to install because they eliminate the need for a separate hot water cylinder, but they are not always the right choice — particularly in larger London properties with high simultaneous hot water demand.
| Factor | Combi Boiler | System Boiler + Cylinder |
|---|---|---|
| Installed cost | £1,250–£2,500 | £1,700–£3,500 |
| Hot water storage | None (instant) | 150–300 litre cylinder |
| Best for | 1–2 bed flats, small terraces | 3+ bed houses, 2+ bathrooms |
| Space needed | Boiler only | Boiler + cylinder cupboard |
| Flow rate | 10–15 litres/min | Unlimited from stored volume |
| Future solar/heat pump ready | Limited | More compatible |
For a one-bedroom flat in Islington or a two-bed Victorian conversion in Brixton, a combi is almost always the right call — lower cost, no cylinder to find space for, and perfectly adequate hot water flow. For a four-bedroom house in Richmond or Chiswick with two or three bathrooms running simultaneously, a system boiler with a well-insulated cylinder will give far better results.
For a deeper comparison of both options, our article on combi vs system boiler in London walks through every scenario in detail, including heat pump compatibility if you are thinking ahead to future upgrades.
Grants and Funding Available for London Homeowners
The boiler replacement cost in London can be dramatically reduced — or eliminated entirely — if your household qualifies for one of the available government or energy supplier schemes. These are not obscure loopholes; they are actively funded programmes that many London households qualify for but never claim.
ECO4 (Energy Company Obligation 4). ECO4 is the main government scheme running until March 2026, with successor funding expected to continue. It requires energy suppliers to fund heating improvements in low-income and fuel-poor households. If you or someone in your household receives Universal Credit, Pension Credit, Child Benefit (at certain income thresholds), or a number of other qualifying benefits, you may be entitled to a fully funded boiler replacement. Renters in private accommodation can also qualify if their landlord consents. Apply through an accredited installer or directly through your energy supplier.
Boiler Upgrade Scheme (BUS). This scheme does not cover gas boiler replacements but provides a £7,500 grant toward an air source heat pump if you are considering switching away from gas entirely. Relevant for London homeowners in well-insulated properties who are planning ahead.
London Borough schemes. Several London councils — including Southwark, Tower Hamlets, and Lambeth — run their own fuel poverty programmes that can supplement ECO4 or provide funding for households that narrowly miss the ECO4 criteria. Contact your borough's housing or environmental health team to ask what is available.
Flexible finance through your installer. For households that do not qualify for grants, many Gas Safe registered installers offer 0% finance over 12–24 months, effectively splitting a £2,000 boiler installation into manageable monthly payments. Always check the total cost of credit before signing — some schemes revert to high APR after an introductory period.
If your boiler has broken down rather than simply reaching end of life, it is worth reading our article on boiler not working in London before committing to a full replacement — sometimes a repair is the faster and cheaper solution.
What to Watch Out For When Getting a New Boiler in London
The London boiler installation market contains excellent engineers and a significant number of poor ones. Price is not a reliable indicator of quality, and the cheapest quote is rarely the best value. Here is what to verify before you hand over any money.
Gas Safe registration is non-negotiable. It is illegal for anyone to work on gas appliances in the UK without being Gas Safe registered. Before booking, check your engineer's registration at gassaferegister.co.uk — you can search by name or registration number and verify the categories they are licensed to work on. Do not accept screenshots or photocopies; check the register directly. Our guide on finding a Gas Safe engineer in London covers what to look for and how to verify credentials. We also cover why this matters in detail in our guide on gas safety certificates in London.
The Benchmark commissioning record. When your boiler is installed, the engineer must complete a Benchmark commissioning checklist — a standardised document confirming the boiler has been set up correctly and safety-tested. Without a completed Benchmark, your manufacturer warranty may be invalid. Ask for it explicitly and keep it with your boiler documents.
Radiator balance check. A new boiler should be balanced across all radiators to ensure even heat distribution. This is often skipped on quick installations. Ask your engineer whether balancing is included or quoted separately.
Avoid cash-only deals with no paperwork. Any engineer asking for cash upfront with no written quote or contract is a risk. A genuine Gas Safe engineer will provide a written quote, a VAT receipt, and a commissioning record. If they are unwilling to provide any of these, walk away.
Annual servicing is not optional. Most boiler warranties require an annual service by a Gas Safe engineer to remain valid. Budget £80–£120 per year for this in London. Our guide on boiler service cost in London covers what is included and what to expect.
Need a New Boiler in London?
Trusted Plumber London provides fixed-price boiler replacement quotes from Gas Safe registered engineers across all London boroughs. Our £60 call-out fee is waived on jobs over 2 hours — and a full boiler swap always qualifies. Checkatrade-listed with verified reviews.
📞 Call 020 7870 3200Frequently Asked Questions
How much does a new boiler cost in London in 2026?
A new combi boiler installed in London costs between £1,250 and £2,500 for supply and fitting. A system boiler with a hot water cylinder typically runs £1,700–£3,500. Budget brands like Ideal and Baxi sit at the lower end; Worcester Bosch and Viessmann units push toward the top. Labour in London adds roughly £350–£700 on top of the unit cost depending on job complexity.
Can I get a free boiler replacement in London?
Yes — the government's ECO4 scheme funds free boiler replacements for homeowners and private tenants who receive qualifying benefits such as Universal Credit, Pension Credit, or Child Tax Credit. Some London boroughs also run local fuel poverty schemes that can help households who narrowly miss ECO4 criteria. Contact your energy supplier or an accredited ECO4 installer to check eligibility — the assessment is free.
How long does a boiler replacement take?
A straightforward like-for-like combi boiler swap in a London terraced house takes one working day — typically 4–6 hours. If the boiler is being relocated, or if the system needs a power flush, magnetic filter, or upgraded pipework, allow a day and a half to two days. A system boiler installation including a new hot water cylinder can run into a second day. Your engineer should give you a realistic time estimate when they quote.