Replacing a boiler is one of the largest home maintenance costs a London homeowner will face. Prices range significantly depending on the boiler type, brand, and complexity of installation. This guide gives you realistic 2026 figures so you know what to expect — and how to avoid overpaying.
Boiler Replacement Costs in London (2026)
| Installation type | Typical London cost |
|---|---|
| Combi boiler replacement (like-for-like) | £1,500–£2,500 |
| System boiler replacement | £1,800–£3,000 |
| Regular (heat-only) boiler replacement | £1,800–£3,000 |
| Converting from regular to combi boiler | £2,500–£4,500 |
| Moving boiler to new location | Add £300–£800 |
| Magnetic system filter (recommended) | Add £100–£200 |
| Power flush (if system is dirty) | Add £300–£600 |
Note: These prices include the boiler unit itself and all installation labour. Parts and labour are typically bundled in a fixed-price quote.
Boiler Costs by Brand
| Brand | Boiler unit cost | Reliability rating |
|---|---|---|
| Worcester Bosch | £900–£1,800 | Excellent |
| Viessmann | £1,200–£2,200 | Excellent |
| Vaillant | £900–£1,600 | Very good |
| Baxi | £600–£1,200 | Good |
| Ideal | £500–£1,100 | Good |
| Glow-worm | £500–£900 | Good |
Labour costs are typically the same regardless of brand — around £400–£700 for a standard installation in London.
Which Type of Boiler Do You Need?
Combi Boiler
Heats water on demand — no hot water cylinder or cold water tank needed. Best for London flats and smaller houses (1–2 bathrooms, up to 3 bedrooms). Around 70% of new London installations are combis.
System Boiler
Works with a pressurised hot water cylinder. Better for larger London homes with 2+ bathrooms and higher hot water demand. More expensive to install but better performance for larger households.
Regular (Heat-Only) Boiler
Requires both a hot water cylinder and a cold water tank in the loft. Found in older London properties. Often converted to combi during replacement to free up space.
Signs Your Boiler Needs Replacing (Not Just Repairing)
- The boiler is over 12 years old
- It has broken down 2+ times in the past year
- Repair costs more than 50% of the new boiler price
- It's a G-rated (non-condensing) boiler — switching to A-rated saves £200–£400/year
- Parts are no longer available from the manufacturer
- Gas bills have risen significantly without a clear reason
For help diagnosing the fault first, see: How much does a boiler repair cost in London?
Get free boiler replacement quotes
Compare quotes from Gas Safe registered engineers across all 32 London boroughs. No obligation.
Get Free Quotes Now →How to Get a Fair Price on a New Boiler in London
- Get 3 quotes minimum — prices for the same installation can vary by £500–£1,000 between engineers
- Only use Gas Safe registered engineers — boiler installation is legally required to be done by a registered engineer. Verify at gassaferegister.co.uk
- Ask about extended warranties — most manufacturers offer 5–10 year warranties when installed by an approved engineer
- Get a written, fixed-price quote — not an estimate. This protects you from bill inflation after the job
- Ask if a power flush is necessary — it often is for systems over 10 years old, but some engineers will recommend it unnecessarily
Government Grants for Boiler Replacement
If you're on certain benefits or in a low-income household, you may qualify for a free or subsidised boiler through the Energy Company Obligation (ECO4) scheme. Check eligibility via your energy supplier or at gov.uk. Some London boroughs also offer additional support through local authority schemes.
Frequently Asked Questions
How long does a new boiler last?
A well-maintained boiler from a quality brand should last 10–15 years. Premium brands like Worcester Bosch and Viessmann regularly achieve 15–20 years with annual servicing.
Do I need a new boiler if mine is 10 years old?
Not necessarily — age alone isn't a reason to replace. If it's working well, services annually, and repairs have been minimal, it may have several good years left. But start getting replacement quotes if it breaks down, as planned replacement is always cheaper than emergency replacement.