What do combi boiler installations cost in 2025?
For a typical London home, the total cost of boiler replacement when fitting a new combi — that’s the boiler itself plus installation — usually lands somewhere between £2,200 and £3,800. Smaller, simpler jobs tend to sit toward the lower end of that range, while larger homes or more involved work naturally pull things higher. If you’d like to dig a bit deeper into how those numbers are put together, our new boiler cost and installation guide goes into more detail.
Here’s a snapshot of the combi boiler installation prices we most often see in London at the moment.
| Job type | What it covers | Typical price (incl. VAT) |
|---|---|---|
| Like-for-like combi swap | Replace old combi in the same location, new condensing combi, standard flue, basic controls | £2,200 – £3,200 |
| Combi swap with upgrades | New combi, magnetic filter, smart thermostat and system clean | £2,600 – £3,800 |
| System/regular to combi conversion | Remove tanks/cylinder, re-route pipework, upgrade gas if needed, install combi & new controls | £3,500 – £5,500 |
These are based on real quotes and invoices from recent jobs, not a price generator. Your exact figure will depend on the boiler size you need, how easy it is to work in the space you have, and whether we’re doing a simple swap or a more involved conversion.
Boiler cost and installation — what you’re really paying for
When people search for “boiler cost and installation” or “combi boiler installation prices”, they’re usually trying to figure out how much of the total is the boiler itself and how much is the fitting work. Breaking it down into those two parts makes everything a lot clearer.
1. Combi boiler price (supply only)
For most London properties, the combi boiler unit on its own comes in at roughly £900 to £1,800. The exact price depends on the brand you go for, how powerful the boiler needs to be and the length of the warranty. Higher output models designed for bigger homes or homes with several bathrooms naturally sit toward the top of that range.
2. Installation cost for a new combi
On top of the boiler, the installation cost — the labour, materials and time — is usually between £1,300 and £2,700, depending on:
- Whether it’s a straightforward swap or a full system conversion
- How easy it is to access the existing boiler, flue and pipework
- Flue length and route (short horizontal runs vs tall verticals, etc.)
- Whether the gas pipework needs upgrading to meet current regulations
- Any extras like smart controls, filters or a system clean
Add those two together and you get to the total cost of boiler replacement for a combi. For most simple combi-for-combi jobs, the final figure tends to sit somewhere in the middle of the ranges shown in the table above.
If you’d like us to price your specific boiler cost and installation instead of guessing from an average, you can send us a couple of photos through our boiler installation page. We’ll come back with a clear, written quote so you can compare it with other boiler fitting London options.
What’s included in our combi boiler fitting service
However simple or involved the job turns out to be, there are a few things that are always part of our standard boiler fitting London service:
- Safe isolation, removal and disposal of your old boiler (where needed)
- Supply of the new combi boiler and standard flue kit
- Installation of the boiler on a secure, level fixing point
- Connection to gas, heating and hot water pipework, with upgrades if required
- System fill, venting, pressure checks and leak tests
- Setup of your chosen controls, whether basic or smart
- Commissioning in line with manufacturer instructions
- Benchmark logbook completed and Gas Safe registration submitted
If your installation needs extras — for example, a powerflush because the water is heavily sludged, or a longer flue kit to reach outside — we’ll explain why and show it clearly on your quote so the complete boiler cost and installation is transparent from the start. And because we also handle general plumbing work in London, we can usually sort out any small plumbing issues we spot while we’re there.
Why people choose ARA for combi boiler fitting in London
There’s no shortage of companies offering boiler fitting London, but there are a few reasons our name keeps coming up in recommendations:
- Gas Safe engineers only. Every combi boiler is installed and signed off by a registered engineer.
- Local London experience. We work in Chelsea flats, Stratford townhouses, Forest Gate terraces and everything in between.
- Clear written pricing. You’ll see exactly how your combi boiler installation prices are made up — no vague line items.
- Electrics and heating covered together. Ideal when your new boiler setup needs wiring alterations or upgraded spurs.
- Neat, respectful work. Dust sheets, tidying up, and taking away the old boiler and packaging as standard.
Abdul has been repairing and replacing boilers across London for well over a decade. He’s usually the one who looks at your photos, checks where your boiler sits now and suggests a sensible combi that matches your property and budget — not just the biggest or most expensive option.
Real combi boiler replacement jobs and prices
To give you a better feel for combi boiler installation prices in real homes, here are a few recent examples of boiler cost and installation from our own work:
Chelsea flat — compact cupboard swap
Small two-bed flat, old combi in a tight kitchen cupboard. We removed the old unit, fitted a modern condensing combi in the same place, added a magnetic filter and a simple wireless thermostat. The cost of boiler replacement for that job came in at just under £2,900, completed comfortably in a day.
Stratford townhouse — system to combi conversion
Three-storey townhouse with a system boiler and cylinder. We removed the cylinder and tanks, re-ran pipework, upgraded the gas supply, installed a high-output combi and performed a full system flush. Total boiler cost and installation was around £4,800, and the owners gained back a full cupboard worth of storage.
Forest Gate terrace — straight combi swap
Victorian terrace with a tired 15-year-old combi that had become unreliable. Like-for-like replacement in the same spot, plus fitting a filter and recommissioning the system. That boiler fitting London job worked out at roughly £2,400, and we had the heating back on the same day.
Combi boiler installation — common questions
What does a combi boiler installation cost?
In London when swapping an old combi for a new one in the same location, the price usually varies between £2,200 and £3,200 in total. If there are any extras added such as a magnetic filter, smart thermostat or a more thorough system clean, that can increase the price upward to betwwen the £2,600–£3,800 range. Full conversions, where we’re changing an older system with tanks or a cylinder over to a combi, typically come in between £3,500–£5,500 because there’s more time and materials involved. We also have a price guide for diffrent boilers, have a look at our new boiler cost and installation page if you’d like a second reference point.
are theyre any hidden fee's outside of the actual boiler installation?
We found the cost of the boiler replacement is depending on how much your plumber is charging for labour. the typical price of a combi boiler on its own might cost £900–£1,800, depending on output, what brand you choose and the warranty thatr comes with it . The installation side — labour, materials, commissioning, setup of your controls and Gas Safe paperwork — usually adds another £1,300–£2,700. If your looking for more of a specifc price on how boiler cost and installation come together have a look at out page it will give you a much more honest picture than just comparing boiler prices in isolation.
What is the average time it takes to fit a new combi-boiler?
A straightforward combi-for-combi replacement normally fits comfortably into a single working day. If there is extra work to be done around removing and replacing the boiler, e.g. a conversion or rerouting pipe work, the timeline can extend betwwen 1-3 days all depednant on how many variables theyre are and what needs to be aletered.
Is it possible to install a combi boiler in a flat that has a small cupboard?
In our experience yes it is possible in most cases, as long as we can leave enoughroom for safe servicing clearances and a suitable flue route, we can find a combi boiler that fits within the space you have.
Do you cover all of London for boiler fitting?
We’re based in London and regularly carry out boiler fitting in areas including Central, East and parts of North and South London — places like Chelsea, Stratford, Forest Gate, Leyton, Tottenham and surrounding postcodes.
How do I get a fixed quote for my home?
The best way we’ve found is for you to send us some images of your boilers on WhatsApp ( 07727 154746 ) and where it is located and where the flue exits the property.when drop us a message if you could just include your postcoe and a rough idea og many radiators and bathrooms you have, that helps us give you a more clear response on your enquiry radiators and bathrooms you have, that helps us size things properly. From there we can put together a clear, fixed combi boiler installation price for you and, if needed, arrange a short visit to double-check the details before booking you in.
Ready to find out your combi boiler installation price?
Whether your boiler has started playing up or you just want to get ahead of it before winter, we can help you choose the right size combi and work out the real boiler cost and installation for your home.
Or call us on 07727 154746. If you’ve got no heating or hot water, let us know when you get in touch and we’ll do our best to prioritise your booking.