A boiler installation is one of the biggest plumbing investments you’ll make. Get the engineer wrong and you risk poor performance, a void warranty and non-compliant installation. Every engineer listed here is Gas Safe registered, independently checked and locally based — covering all London boroughs and the City.
✅ Gas Safe registration checked against the Gas Safe Register where applicable
✅ Insurance and business identity and contact details verified
✅ Verified by our 16-point process (see how we verify plumbers →)
✅ Work guarantees available — confirm with your plumber
Find a Verified Boiler Installation Engineer in Your Borough — Call Now →
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Every listing is verified before it goes live — Gas Safe registration confirmed directly with the Gas Safe Register, service coverage confirmed and contact details validated. No paid placements go live without verification — listing comes after checks, not before.
Already know your borough? Jump to the borough grid below. Contact 2–3 verified engineers to compare quotes, and confirm they supply and install your preferred boiler make before anyone visits.
If an engineer cannot provide a written quote with parts and labour itemised, move to the next — a boiler installation is not a job to price verbally.
Compare Verified Boiler Installation Engineers in Your Borough — Call Now →
What to decide before you call a boiler installation engineer
1. Replacement or new system
Most London boiler installations are like-for-like replacements — same boiler type, same location, same pipework configuration.
These are faster, cheaper and simpler than system changes. If you are switching boiler type — combi to system, back boiler to combi, or moving the boiler location — expect higher costs, longer installation time and more complex certification requirements. Know which category you are in before you call.
2. Boiler make and model
You do not have to accept whatever boiler an engineer supplies. You can specify the make and model — or ask for three options at different price points with honest pros and cons.
Major UK manufacturers such as Worcester Bosch and Vaillant dominate the London market, alongside Baxi, Ideal and Viessmann. Each has different warranty terms, parts availability and service network coverage across London boroughs.
Ask your engineer which make they install most frequently and why — the answer tells you a lot.
3. Building Regulations notification
Every gas boiler installation is notifiable under Building Regulations Part L. As required by Gas Safe Register guidance, your engineer must notify the installation and you should receive a certificate.
You will receive a Building Regulations Compliance Certificate — keep this. It is the document you will need when selling the property. If your engineer does not mention this process, ask directly before work starts.¹
4. Warranty registration
Manufacturer warranties are a separate process from Building Regulations notification. Most require registration via the manufacturer’s portal or app within a set window after installation, completion of the Benchmark commissioning checklist, and a commitment to annual servicing.
Some manufacturers require brand-accredited installation for their extended warranty terms — confirm with your engineer before committing to a make. If it isn’t registered correctly and conditions aren’t met, it isn’t the warranty on the box.
5. Boiler Plus compliance
Since 2018, every combination boiler installation in England must include an additional energy efficiency measure under Boiler Plus regulations — a load compensator, weather compensator, or smart thermostat with automation and optimum start control.
This is a Building Regulations requirement under Approved Document L1b, not optional. If a quote does not reference a compliant control, the installation may not meet Part L. Ask your engineer which Boiler Plus measure is included before accepting any quote.²
6. Get three quotes
Boiler installation prices in London vary significantly between engineers — not always because of quality differences, but because of parts margin, call-out structures and overhead differences.
Three quotes give you a market picture. The cheapest is rarely the best. The most expensive is rarely necessary. The middle quote from a verified, Gas Safe registered engineer with a clear written breakdown is usually the right call. See our How to Read a Plumbing Quote guide before you compare.
What boiler installation costs in London
London boiler installation rates sit above national averages due to operating costs specific to the capital — including parking restrictions, congestion-related delays and insurance requirements.
These are the realities of a compliant, Gas Safe registered London engineer — not excessive margins. Many homeowners compare headline prices without checking what the quote includes — whether the boiler, flue, controls, filter and commissioning are all covered, or whether these are charged separately.
Typical current ranges for London boiler installation work are outlined below. Actual costs vary by boiler make, installation complexity, property type and access.
Always confirm exactly what is included before accepting any quote. See our London Plumbing Costs Guide for the full breakdown.
| Service | Typical London range |
|---|---|
| Like-for-like combi boiler replacement (supply and fit) | £2,500–£4,500 |
| System boiler replacement (supply and fit) | £2,500–£4,000 |
| Back boiler to combi conversion | £3,000–£5,000 |
| Boiler relocation (same property) | £500–£1,500 additional |
| Magnetic filter installation (recommended) | £150–£250 |
| Smart thermostat / Boiler Plus control | £150–£300 |
| Flue extension or reroute | £200–£600 |
Always confirm whether the quote includes the boiler, flue components, filter, Boiler Plus control, disposal of the old unit, all labour, Gas Safe notification, Building Regulations compliance certification and warranty registration.
An incomplete quote is not a competitive quote — it is an incomplete price.
Why London boiler installation is different from anywhere else in the UK
Combination boiler dominance and space constraints
London properties — particularly flats, conversions and Victorian terraces — are space-constrained in ways that most of the UK is not.
Boiler cupboards, airing cupboards repurposed for combis, and kitchen installations in galley layouts all create access and flue routing challenges that add time and cost.
Current standards under BS 6798 recommend internal condensate pipe runs wherever possible — where an external run is unavoidable, a minimum 30mm internal diameter pipe, fully insulated, is the specification to reduce freeze risk.³
An engineer who installs predominantly in London properties plans for these constraints. One who doesn’t quotes for a straightforward installation and finds complications on the day.
Hydrogen-ready boilers
Many new gas boilers supplied in the UK are now marketed as hydrogen-ready or hydrogen-blend ready — capable of operating on a blend of up to 20% hydrogen without modification.
This is now standard across most new boilers from major manufacturers, not a separate legal requirement for existing homes, but worth confirming when comparing models.
Hard water and filter requirements
Much of London sits in the hard to very hard water range — Thames Water confirms that all water in their supply area is hard.⁴
Installing a boiler in London without a magnetic system filter is a mistake — limescale and magnetite accumulation will shorten the life of the new boiler and may void the manufacturer warranty.
Most reputable engineers include a filter as standard. If a quote does not include a filter, ask why before accepting it. See our London Hard Water Guide for the full picture.
Flue regulations in conservation areas and listed buildings
A significant proportion of inner London properties sit within conservation areas or are listed buildings.
External flue positioning is subject to planning constraints in these areas — a standard rear or side flue may require permitted development checks or, for listed buildings, separate listed building consent depending on the works involved.
Your engineer should identify this before installation day, not during it. If your property is in a conservation area or listed, raise this at the quoting stage.⁵
Back boiler removal in older stock
Back boilers — gas fires with a boiler unit behind — are still present in parts of London’s older housing stock, particularly in inner south and east London.
Removing a back boiler and installing a combination boiler is a more complex job than a like-for-like replacement: the fireplace void needs to be made good, the flue liner needs replacing, and the pipework configuration changes significantly.
Confirm your engineer has specific experience with back boiler conversions before committing. See our Victorian Terrace Plumbing Guide for what older London properties typically contain.
Landlord and rental property installations
Any boiler installation in a London rental property requires Gas Safe notification and a Building Regulations Compliance Certificate issued on completion.
The landlord’s annual gas safety inspection obligation resets from the installation date. Engineers listed here cover landlord and rental property installations and will issue the correct documentation on completion. See our Landlord Plumbing Compliance Checklist for the full obligations.
Find a verified boiler installation engineer in your London borough
Every engineer below is Gas Safe registered and independently checked before listing. Find your borough and call now.
Inner South London
- Boiler Installation Greenwich
- Boiler Installation Lewisham
- Boiler Installation Southwark
- Boiler Installation Lambeth
- Boiler Installation Wandsworth
- Boiler Installation Merton
Inner North London
- Boiler Installation Islington
- Boiler Installation Hackney
- Boiler Installation Camden
- Boiler Installation Haringey
- Boiler Installation Tower Hamlets
Inner East London
- Boiler Installation Newham
- Boiler Installation Waltham Forest
- Boiler Installation Barking & Dagenham
- Boiler Installation Redbridge
- Boiler Installation Havering
Inner West London
- Boiler Installation Hammersmith & Fulham
- Boiler Installation Kensington & Chelsea
- Boiler Installation Westminster
- Boiler Installation Ealing
- Boiler Installation Hounslow
- Boiler Installation Richmond
Outer South London
- Boiler Installation Bromley
- Boiler Installation Croydon
- Boiler Installation Sutton
- Boiler Installation Kingston
Outer North London
- Boiler Installation Barnet
- Boiler Installation Brent
- Boiler Installation Harrow
- Boiler Installation Hillingdon
- Boiler Installation Enfield
Outer East London
The City
- Boiler Installation City of London
Frequently Asked Questions
Yes — this is a legal requirement. Any gas boiler installation must be carried out by a Gas Safe registered engineer.
Your engineer must notify the installation under Building Regulations, and the local authority should be notified within 30 days. You should then receive a Building Regulations Compliance Certificate — keep it safe, as you may need it when selling the property. Verify registration at gassaferegister.co.uk before committing to any engineer.
A straightforward like-for-like combi boiler replacement typically takes one day.
More complex installations — including back boiler conversions, system changes or boiler relocations — often take one to two days depending on access, pipework changes and flue routing. Confirm the expected timescale at the quoting stage, especially if you are in a flat or a property with restricted access.
A complete quote should clearly itemise the boiler itself, flue components, controls, removal and disposal of the old unit, all labour, Gas Safe notification, Building Regulations compliance certification and warranty registration.
Many installers also include a magnetic system filter as standard because it helps protect the boiler from sludge and debris. If key items are missing or vaguely described, ask why before accepting the quote.
A well-maintained boiler will often last around 12 to 15 years, and proper annual servicing helps protect both performance and warranty cover.
In London, hard water can accelerate wear, so good system protection matters. Measures such as annual servicing, inhibitor treatment and a magnetic filter can all help reduce sludge-related damage and extend service life.
Many new gas boilers are marketed as hydrogen-ready or hydrogen-blend ready. In practice, most modern boilers can already operate on a gas blend containing up to 20% hydrogen without modification.
It is not a separate legal requirement for existing homes, but it is worth asking about when comparing models so you understand exactly what is being claimed and whether it offers any real advantage.
Related services
- Boiler Repair London
- Boiler Servicing London
- Central Heating Repair London
- Emergency Plumber London
- General Plumbing London
Related guides
London Plumbing Costs Guide
London Hard Water Guide
How to Read a Plumbing Quote
Landlord Plumbing Compliance Checklist
Victorian Terrace Plumbing Guide
Every engineer on this directory is Gas Safe registered and independently checked before listing — not after something goes wrong. Registration confirmed directly with the Gas Safe Register. Insurance confirmed.
Local coverage confirmed. Many offer work guarantees — check their profile before you call. A new boiler is a 12-year decision. The engineer who installs it matters as much as the boiler itself. Find your borough. Call now.
Find a Verified Boiler Installation Engineer in Your Borough — Call Now →
Sources
¹ Gas Safe Register — Building Regulations and boiler installation notification
https://www.gassaferegister.co.uk/gas-safety/gas-safety-certificates-records/building-regulations-certificate/
² Heating & Hotwater Industry Council — Boiler Plus guidance and Approved Document L1b
https://www.hhic.org.uk/consumer-advice/boiler-plus/
³ Heating & Hotwater Industry Council — Condensate pipe standards (BS 6798 guidance)
https://www.hhic.org.uk/consumer-advice/condensate-pipe-guidance/
⁴ Thames Water — Water hardness in London
https://www.thameswater.co.uk/help/water-quality/hard-water
⁵ Historic England — Permitted development and conservation areas
https://historicengland.org.uk/advice/your-home/making-changes-your-home/planning-permission/