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Boiler replacement cost: what it really costs in 2026
Like-for-like swaps to full system upgrades.
£2,800 – £5,600
A like-for-like combi swap starts around £2,800. Adding a system upgrade takes it to roughly £4,200, and premium boilers with full works around £5,600.
Price by spec
| Option | What it means | Typical price |
|---|---|---|
| Combi like-for-like | Same position, straightforward swap | £2,800 – £3,500 |
| With system upgrade | New controls, filter, flush | £4,200 – £4,800 |
| Premium install | Top-tier boiler, long warranty | £5,600+ |
What actually happens
- Old boiler drained and disconnected
- New boiler mounted and flued
- Connected to gas, water and heating circuits
- System power-flushed and inhibitor added
- Smart controls or thermostat fitted
- Commissioned, certified and registered for warranty
Popular choices
Smart thermostat controlMagnetic system filter10–12 year manufacturer warranties
Regulations to know
- Gas boiler work is illegal unless done by a Gas Safe registered engineer — always check the card
- The installer should self-certify the job with building control and register your warranty
Tips from the trade
- A power flush with the swap protects the new boiler — cheap insurance
- Oversizing wastes money; a heat-loss calculation beats guesswork
Plan this project properly
Get a region-adjusted estimate, track budget against real quotes, and find local tradespeople -- free to browse on Qome.
Start planning on QomePrices on this page are approximate, region-adjusted guide figures built from cross-checked UK cost data. They exist to inform you, not to bind anyone. Actual prices are whatever you and your tradesperson agree, and a difference between a Qome guide figure and a real quote is not a fault in either.