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Replacing a boiler in Streatham? A new boiler is notifiable building work, so the installer’s Gas Safe registration and paperwork matter as much as the price — and every engineer here is checked before listing.
✅ Checked before listing — identity, insurance, trading presence, Gas Safe (where relevant).
✅ Workmanship guarantee badges on listings — 1, 3, 6 or 12 months
⚠️ Smell gas? Leave the property and call the National Gas Emergency Service free on 0800 111 999 from outside (24h). A poorly running gas appliance can also produce carbon monoxide, which you can’t smell — gas-safety steps & CO signs ↓.
Contact verified boiler engineers in Streatham ↓
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Coverage: Streatham and the wider SW16 area, including the High Road and town centre, Streatham Hill, Streatham Common, Streatham Vale and Streatham Wells.
What this covers: supply and installation of new gas boilers (combi, system and regular) and swaps, including the Boiler Plus controls and the Building Regulations notification. For a boiler that can still be fixed, see Boiler Repair in Streatham; to keep a new boiler’s warranty, Boiler Servicing in Streatham.
Costs: a new boiler is a project price, not a callout — see What a new boiler costs.
Availability: listed engineers set their own hours and lead times; ask about survey and fitting slots.
A new boiler is notifiable work: Boiler Plus and your Building Regs certificate
A boiler swap isn’t just a fitting job — it triggers two sets of rules a good installer handles for you.
Current efficiency guidance. Under the currently operative Approved Document L, the normal minimum for wet gas heating is 92% ErP. For installations in existing dwellings, Table 6.2 contains a defined exceptional-circumstances route permitting lower SEDBUK 2009 efficiencies where its procedure applies. When a gas-fired combination boiler is installed in an existing dwelling, it must also include at least one of the four additional Boiler Plus measures: flue-gas heat recovery, weather compensation, load compensation, or a smart control with automation and optimisation.1 The published 2026 Approved Document L does not become operative until 24 March 2027 for ordinary work, so this page uses the 2021 edition incorporating 2023 amendments.
Building Regulations notification. A registered installer normally self-certifies and submits the notification through the competent-person arrangements. The compliance certificate is then issued through the relevant scheme or registered organisation for the property; it should not be described simply as a certificate personally issued by the engineer.2
Commissioning and warranty records. The installer should complete the Benchmark commissioning record and follow the manufacturer’s instructions for cleaning, water treatment, controls and handover. Many manufacturer or extended-warranty terms depend on correct commissioning and documentary evidence, but the exact warranty terms remain decisive; the installation record does not override statutory consumer rights. Only an appropriately qualified Gas Safe registered engineer may carry out the gas installation work.
Low-carbon alternative? As at July 2026, BUS grants are £7,500 for air-to-water, ground-source and water-source heat pumps; £2,500 for residential air-to-air heat pumps; and £5,000 for eligible biomass boilers. A £9,000 grant for eligible off-gas-grid air-to-water or ground-source installations applies from 21 July 2026 to 31 March 2027. The scheme has been extended to 2030. Developer-built new homes and social housing are generally excluded, but qualifying individual self-builds can receive heat-pump funding.5
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A pre-quotation survey should cover room-by-room heat loss and radiator output, hot-water demand and simultaneous use, dynamic mains flow and pressure before proposing a combi, gas working pressure, meter and internal gas-pipe capacity, the flue route and terminal clearances, plume effects on neighbouring windows or walkways, the condensate route, fall, frost protection or need for pumping, existing system-water condition, service clearances and future access. In an upper-floor converted flat, weak mains flow or a flue route through shared structure can make a proposed combi unsuitable; a stored-hot-water system may be a better fit. Freeholder consent, planning restrictions, scaffolding or access through another demise are separate questions that must be confirmed before the installation date.
Water treatment also has separate purposes. Cleaning and inhibitor protect the primary heating circuit against corrosion. An inline or magnetic filter captures magnetite and circulating debris. Suitable hardness protection on the incoming cold-water or domestic-hot-water side is considered only where the appliance instructions, measured water conditions and system design justify it; a magnetic filter is not limescale protection.6
Safety first
If you smell gas or suspect a leak, follow the HSE domestic emergency guidance: avoid flames and electrical switching, ventilate if safe, shut the meter control valve if safely accessible, leave if necessary and call 0800 111 999 from outside.7
The Streatham gas network is operated by SGN up to your meter; the emergency number above is the one to call for a leak.8
Carbon monoxide. A poorly running or badly installed gas appliance can produce CO — colourless and odourless. Fit a CO alarm meeting BS EN 50291, sited per the manufacturer’s instructions.
Gas work is Gas Safe work. Installation, commissioning and the final connection of pipework to a gas boiler must be done by a Gas Safe registered engineer.4 Landlords: a new appliance must have its annual gas safety check within 12 months and be maintained thereafter.
Find a verified installer by Streatham district
- Streatham Hill — larger homes may need a room-by-room heat-loss calculation, radiator-output review and hot-water-demand assessment before any conversion is proposed.
- Streatham High Road and town-centre flats — flue, plume and condensate routes may cross shared structure or commercial space, so freeholder, neighbouring-access and building-management requirements should be confirmed before the installation date.
- Streatham Common and Vale — measured mains flow and simultaneous hot-water demand should decide whether a combi or stored-hot-water arrangement is suitable; the property type alone does not decide it.
- Streatham Wells and Leigham Court Road — surveys should confirm gas-pipe capacity, existing-system condition, service access and the practical flue and condensate route.
Streatham’s Southern and Thameslink stations (Zone 3) keep listed installers within easy reach of the SW16 core.
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| Job | Typical Streatham range (editorial estimate) |
|---|---|
| Combi swap, like-for-like (mid-range boiler, fitted) | £2,100–£3,400 |
| Combi swap with Boiler Plus control and any specified water-treatment measure | £2,500–£4,000 |
| Conversion (e.g. conventional system to combi) | £3,300–£5,200+ |
| System boiler + cylinder (larger homes) | £3,200–£5,800+ |
Editorial estimate only — indicative ranges to sense-check a quote, NOT regulated rates, market data or a published cost survey. Price depends on boiler make/model, flue and pipework changes, and controls. Streatham is inside the London-wide ULEZ and outside the central Congestion Charge zone.
Frequently asked questions
For wet gas heating, the normal minimum is 92% ErP, subject to the defined exceptional-circumstances procedure for certain installations in existing dwellings. The four additional combi measures apply when a gas-fired combination boiler is installed in an existing dwelling.1
A Building Regulations Compliance Certificate — your Gas Safe engineer notifies the local authority within 30 days and the certificate is issued for the property.2
Often, but the installer must first confirm the flue route, terminal clearances and plume effects. Check the lease and obtain freeholder or planning approval where the alteration affects shared structure, a listed building or a restricted elevation; approval is not automatic for every replacement.
Not automatically. The installer should follow the boiler manufacturer’s instructions and measured water conditions. Primary-circuit inhibitor and filtration address corrosion and debris; any domestic-water hardness measure is selected separately for limescale risk.6
It depends on hot-water demand, pressure and bathrooms in use at once — see Combi vs System Boiler.
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Why verified plumbers — not a general directory
A boiler installation is gas work with paperwork attached, so Gas Safe registration is the credential we put first. Every listing is checked before it goes live and re-verified annually: we confirm the business is legitimately trading and verify the named contact, we check evidence of public liability insurance, and we confirm the plumber covers Streatham’s SW16 postcodes before a profile is approved — and we keep an eye on customer feedback gathered from across the web. Where gas is involved we confirm Gas Safe registration directly with the Gas Safe Register — and on an install, ask to see the ID card and confirm the Building Regs notification is handled. For non-gas work you can look a plumber up yourself on WaterSafe.
Listed plumbers pay a flat monthly fee to be listed. What that fee never buys is the verification itself — every listing is checked on the same terms — and there’s no per-enquiry middleman fee, so your enquiry goes directly to the plumber. Profiles may be suspended or removed if credentials lapse or credible concerns are raised; see the full verification process →.
Related areas
Verified plumbers across Streatham’s neighbourhoods and its near neighbours, including:
- Balham
- Brixton
- Norbury
- Thornton Heath
- Tooting Bec
- Tulse Hill
Related services
Other verified plumbing services in Streatham:
- Emergency Plumber in Streatham
- Burst Pipes in Streatham
- Leak Detection in Streatham
- Blocked Drains in Streatham
- Toilet Repairs in Streatham
- Tap Repair & Installation in Streatham
- General Plumbing in Streatham
- Bathroom Plumbing in Streatham
- Kitchen Plumbing in Streatham
- Washing Machine & Dishwasher Installation in Streatham
- Boiler Repair in Streatham
- Boiler Servicing in Streatham
- Central Heating Repair in Streatham
- Commercial Plumbing in Streatham
Related guides
- Should I Repair or Replace My Boiler? — London 2026
- Combi vs System Boiler UK: Which Is Better in 2026?
- London Hard Water — Homeowner & Landlord Guide 2026
- London Plumbing Costs & Compliance Guide 2026
A new boiler in Streatham begins with the survey: heat loss, hot-water demand, mains flow, gas capacity, flue and condensate feasibility, system condition and access. The selected boiler and controls are then commissioned, the system is treated for the correct risks and the notification and handover records are completed. Compare verified Gas Safe installers below.
Contact verified boiler engineers in Streatham ↑
Last reviewed: July 2026 by Adiel Khan — SFEDI-accredited business advisor, 20+ years’ experience (South East Enterprise Ltd) and operator of VerifiedPlumbers. LinkedIn ↗
This page is checked for compliance and regulatory accuracy against the bodies cited on it — GOV.UK Boiler Plus, the Gas Safe Register, HHIC Benchmark, Ofgem, HSE, Thames Water and SGN. Source links are provided within this page where relevant.
Sources & further reading
1. GOV.UK — current operative Approved Document L, Volume 1 (2021 edition incorporating 2023 amendments), paragraphs 6.1–6.2 and Tables 6.1–6.2: https://assets.publishing.service.gov.uk/media/662a2e3e55e1582b6ca7e592/Approved_Document_L__Conservation_of_fuel_and_power__Volume_1_Dwellings__2021_edition_incorporating_2023_amendments.pdf
2. Gas Safe Register — Building Regulations Compliance Certificate: https://www.gassaferegister.co.uk/gas-safety/gas-safety-certificates-records/building-regulations-certificate/
3. HHIC Benchmark code of practice: https://www.hhic.org.uk/uploads/5D9B41557255E.pdf
4. Gas Safe Register — official register and ID card: https://www.gassaferegister.co.uk/
5. Ofgem — Boiler Upgrade Scheme property-owner grant values, eligibility and self-build exception, current July 2026: https://www.ofgem.gov.uk/environmental-and-social-schemes/boiler-upgrade-scheme-bus/boiler-upgrade-scheme-bus-property-owners
6. HHIC — primary-system corrosion treatment, filtration and separate limescale protection: https://hhic.org.uk/uploads/6904A36486490.pdf
7. HSE — domestic gas-emergency guidance: https://www.hse.gov.uk/gas/domestic/faqs.htm
8. SGN — gas distribution network (south of England): https://www.sgn.co.uk/</a>