How much does it cost to install a new boiler in London? Combi, system and heat-only boilers, supply and fit prices by brand, and what affects the final cost.
New Boiler Installation Costs in London 2025
Boiler installation costs in London are typically 20–40% higher than the national average, reflecting London labour rates and the complexity of London's housing stock (period conversions, flats with limited access, and older pipe systems).
Combi Boiler Supply and Fit — London Prices
| Brand / Model | Supply + Fit (London) |
|---|---|
| Vaillant ecoTEC Plus 30kW | £2,200–£2,800 |
| Worcester Bosch Greenstar 8000 30kW | £2,300–£2,900 |
| Baxi 800 Combi 30kW | £1,800–£2,400 |
| Ideal Logic Max 30kW | £1,700–£2,200 |
| Viessmann Vitodens 100-W 30kW | £2,400–£3,100 |
System Boiler + Cylinder — London Prices
A system boiler with a new unvented hot water cylinder costs significantly more: £3,000–£5,500 including the boiler, cylinder, and installation. Required in London properties where hot water demand is high (multiple bathrooms) or where mains pressure is insufficient for a combi.
What Affects Boiler Installation Cost in London
- Flue run — a long or complex flue adds £100–£400 to the cost. London period flats often have challenging flue routes.
- System flush — a power flush before installation (recommended for old systems) adds £300–£500
- Pipework modifications — condensate pipe run to an external drain adds £100–£300
- Gas meter upgrade — if the existing meter cannot supply a larger boiler, a meter upgrade is required (coordinated with Cadent, often free)
- Location change — moving the boiler from a different room requires new pipework runs, adding £300–£800
- London flat access — working in a high-rise flat or a period conversion with limited access adds time and cost
Frequently asked questions
How long does a new boiler installation take in London?
A standard combi boiler replacement (same location, same type) takes 6–8 hours in most London properties — a skilled Gas Safe engineer can complete it in a single day. More complex installations (first-time installation, location change, new cylinder) typically take 1.5–2 days. London flats in high-rise buildings may require slightly more time for flue access and building manager coordination.
Should I get the cheapest boiler in my London rental property?
Budget boilers (Ideal Logic, Baxi 600 series) are reliable and significantly cheaper than premium brands. For a London rental property where the boiler sees heavy use and minimal maintenance attention from tenants, a mid-range or premium boiler often delivers better long-term value through longer warranty periods, better parts availability, and lower repair frequencies. Vaillant and Worcester Bosch offer 10-year parts guarantees on certain models — worth considering for a property you plan to hold for 10+ years.
Can I get a grant for a new boiler in my London property?
The Boiler Upgrade Scheme (BUS) only applies to heat pumps and biomass boilers — not gas boilers. The ECO4 scheme (Energy Company Obligation) provides free or heavily subsidised boiler replacements for low-income households in properties with low EPC ratings. London landlords do not generally qualify for ECO4 unless their tenant meets the income criteria. Check eligibility on the GOV.UK ECO scheme page.