Gas Safe fitter · 8–10 year warranty · Benchmark commissioning
Boiler Installation London
Gas Safe registered boiler installation across every London borough — Worcester Bosch, Vaillant, Ideal, Baxi, Viessmann. Combi, system and heat-only. Benchmark commissioning, Building Regs notification, extended manufacturer warranty registered.
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Boiler installation — Gas Safe, Benchmark, warranty-registered
A boiler installation is the largest single mechanical purchase in most London homes, and it is one where getting the specification right matters as much as getting the install price right. The wrong boiler in the wrong property is expensive to run, uncomfortable to use, and can fail a decade before its useful life. The right boiler — correctly sized, from the right brand for your priorities, installed by an accredited fitter with the manufacturer warranty properly registered — delivers 12–15 years of quiet, reliable operation with a full-length warranty backing the equipment.
Every install we deliver is by a Gas Safe registered engineer (statutory UK gas register), fitted to full manufacturer specification, commissioned via the Benchmark scheme (industry-standard commissioning record + Building Regs notification), and warranty-registered with the manufacturer. We hold accredited-installer status on Worcester Bosch (unlocks 8-year warranty), Vaillant (Advance Installer scheme — 10-year warranty), and Ideal Logic Max (10-year warranty on registered installs). Extended warranty registration is conditional on annual service by a Gas Safe registered engineer; we handle the annual service so the warranty stays in force year-on-year.
The four boiler categories we install cover every domestic scenario. Combi boilers for 1–2 bathroom flats and homes. System boilers feeding new unvented hot water cylinders for 2+ bathroom homes needing mains-pressure DHW at every outlet simultaneously. Heat-only (regular) boilers for like-for-like replacement in period properties where the existing vented system is being retained. And hybrid heat-pump + gas boiler installations for eco-refurbishment projects where the space heating is delivered by an air-source heat pump with the boiler providing DHW and winter backup.
Where the install involves a new unvented hot water cylinder (combi-to-system upgrade), the cylinder side is delivered by our G3 certified engineer (UK Certification Ltd certificate 136359 issued 8 September 2025, expiry 18 August 2030) and a Building Notice is submitted to the local authority Building Control team. Gas Safe covers the boiler and gas connections; G3 covers the unvented cylinder under Building Regs Part G3; WaterSafe (Water Regulations 1999 competency, certificate 136356 same period) covers the cold supply-side work. All three qualifications on the same engineer, one visit, one invoice, one accountable installer. Public liability £5,000,000 via SiriusPoint through Eaton Gate MGU, policy BE26ACTT000000018221, period 07/05/2026 to 06/05/2027.
Four boiler types — which one is right for your property
Combi boiler
Single-appliance boiler heating both DHW and radiators. No cylinder or loft tank. Best for 1–2 bathroom flats and homes. Compact form factor, wall-mounted. Typical output 24–35 kW.
Pros: Compact, no cylinder needed, cheapest to install.
Cons: Struggles with simultaneous DHW demand at 2+ bathrooms; flow rate capped by boiler kW.
System boiler
Sealed-system boiler feeding an unvented hot water cylinder. Mains-pressure DHW at every outlet simultaneously. Standard for 2+ bathroom homes. Typical output 24–35 kW.
Pros: Simultaneous multi-outlet DHW, mains-pressure showers, no loft tank.
Cons: Requires cylinder and airing-cupboard space. Higher install cost than combi.
Heat-only (regular) boiler
Traditional boiler feeding a vented cylinder and loft header tank. Common in Victorian and Edwardian properties. Being replaced with system boilers on modern refits.
Pros: Compatible with existing vented systems, keeps low-pressure historic pipework.
Cons: Weak shower pressure (0.1–0.3 bar), loft tank flood risk, less energy-efficient.
Hybrid heat pump + boiler
Hybrid system combining an air-source heat pump for space heating with a gas boiler backup for winter peak and DHW. Increasingly specified for eco-refurbishments.
Pros: Lower carbon emissions, energy cost reduction, BUS grant eligible.
Cons: Higher install cost. Requires outdoor unit for the heat pump. Best-in-class integration needs Vaillant or Daikin ecosystem.
The six-stage install workflow
Property survey and boiler sizing
On-site survey to confirm boiler type, output kW required (based on radiator count, DHW demand, and property heat loss), condensate discharge route, flue route, gas pressure at meter, and Building Regs notification path. Written quote issued within 24 hours of survey visit.
Brand and warranty selection
Brand recommendation based on your priorities — best warranty (Vaillant 10 year, Ideal Logic Max 10 year), best reliability (Worcester Bosch), best value (Alpha, Baxi). Extended warranty registration by accredited installer status on Worcester and Vaillant. Full manufacturer literature supplied ahead of install.
Building Regs notification (Benchmark)
Every gas boiler installation is notifiable under Building Regulations. Notification submitted via the Benchmark scheme — GasSafe engineer registers the install, boiler manufacturer receives the commissioning data, local authority Building Control is auto-notified. Benchmark certificate supplied to customer with the install pack.
Installation day — same-day or two-day depending on scope
Simple combi replacement 1 day. Combi-to-system upgrade with new cylinder 2 days. Property drained, existing boiler removed, new boiler installed with all new isolation valves and gas connections, condensate discharge fitted, flue installed (horizontal or vertical), system refilled and pressurised.
Commissioning and testing
Full commissioning to manufacturer specification — flue gas analysis (CO/CO₂ ratio checked), gas rate verified, water pressure across DHW and heating verified, condensate trap primed, error log cleared, warranty registered with manufacturer. Landlord Gas Safety Record issued if property is a rental.
Handover and paperwork
Full customer walkthrough — boiler controls, thermostat programming, hot water schedule, pressure top-up procedure, what to do if the boiler locks out. Install pack: Gas Safe certificate, Benchmark commissioning record, warranty registration, Building Notice reference, invoice, and manufacturer manual.
Cost — boiler installation in London
| Scope | Price (inc. VAT) | Includes |
|---|---|---|
| Combi boiler replacement (like-for-like, mid-range brand) | £2,100–£2,850 | Boiler supply, Gas Safe install, Benchmark commissioning, waste haulage, 5-year warranty |
| Combi boiler replacement (premium brand — Worcester, Vaillant) | £2,650–£3,650 | Boiler supply, install, 8-year (Worcester) or 10-year (Vaillant) accredited-installer warranty |
| System boiler + new unvented cylinder | £4,650–£6,850 | Boiler, 210–250L Megaflo Eco Indirect cylinder, G3 safety kit, install, Building Notice, G3 certificate |
| Heat-only boiler like-for-like replacement | £1,950–£2,850 | Boiler supply, install, commissioning, existing vented cylinder retained |
| Gas hob or gas cooker install (as part of boiler visit) | +£165–£280 | Gas connection, isolation valve, commissioning |
| Powerflush of heating circuit (add-on) | +£450–£750 | Full powerflush of existing radiators before new boiler install — recommended on systems 10+ years old to protect new boiler warranty |
Real London boiler installs
Camden NW1 flat — Vaillant ecoTEC Plus 25kW combi replacement
Existing 22-year-old combi failing on the DHW plate heat exchanger. Replaced with Vaillant ecoTEC Plus 25kW combi as accredited installer — 10-year manufacturer warranty registered. Single-day install, Benchmark commissioning, Landlord Gas Safety Record issued. Total £2,950.
Chiswick W4 townhouse — Worcester Greenstar 30kW system + 210L Megaflo
Family upgrading from failing combi to full system boiler + unvented cylinder for two-bathroom mains-pressure delivery. Worcester Greenstar 30kWi system boiler with 8-year accredited-installer warranty, 210L Megaflo Eco Indirect. Two-day install. Building Notice submitted to Hounslow Council Building Control. Total £5,650.
Enfield EN2 landlord portfolio — Ideal Logic Max 5-boiler contract
Landlord replacing 5 aged combis across a rental portfolio in Enfield. Ideal Logic Max 30kW combis with 10-year warranty. Consolidated portfolio pricing (£2,450 per install), CP12 records issued for each property post-install, single monthly invoice. All 5 completed within a 3-week window.
Boiler installation across every London borough
Frequently asked questions about boiler installation
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Gas Safe fitter, Benchmark commissioning, 8–10 year manufacturer warranty registered.
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