Buying advice

How much does a new boiler cost in 2026?

Straight answer: £1,800 to £4,500 installed for a like-for-like swap in most UK homes. Below that, the quote probably excludes something you'll need. Above that, you're either getting premium kit or the job is more complex than a standard swap.

2026 prices by boiler type

Combi swap (like-for-like)

£1,800 – £3,500

Replacing an existing combi with a new combi in the same position. Most common job. Budget: Baxi / Ideal Logic+ £1,800–£2,500. Mid: Worcester Greenstar / Vaillant ecoTEC £2,400–£3,200. Premium: Viessmann / Vaillant Exclusive £3,000–£3,500.

Install time: 1 day

System boiler swap

£2,200 – £3,800

System boilers work with a hot-water cylinder. Includes pump + expansion vessel built in. Slightly more expensive than combi of same output.

Install time: 1–2 days

Conventional (regular) boiler swap

£2,000 – £3,500

Uses cold-water tank and hot-water cylinder. Being phased out but still common in older homes. Cheapest type, but adds cost if you also replace the cylinder.

Install time: 1–2 days

Convert regular → combi

£2,800 – £5,000

Removes old tank + cylinder, installs combi. Frees up loft / airing cupboard space. Main cost drivers: pipework rerouting, plaster-making-good.

Install time: 2–3 days

Back boiler → combi

£3,200 – £5,500

Removes back boiler behind gas fire, installs new combi on kitchen/utility wall. Biggest cost driver: new flue penetration, pipework routing, making good the fireplace.

Install time: 2–3 days

Move boiler position

+£500 – £1,500 on top

Moving the boiler to a different room or wall adds pipework, flue, and gas rerun. Worth it for hiding the boiler but adds meaningful cost.

Install time: +1 day

What your quote should include

A legitimate fixed-price quote covers all of these. Watch for ones that "exclude" items that invariably end up on the bill:

✓ The boiler itself, warranty registered
✓ Installation labour (Gas Safe engineer)
✓ Standard flue (up to 1m)
✓ System flush (chemical flush minimum)
✓ Magnetic system filter (Adey MagnaClean or equivalent)
✓ Wireless thermostat / smart control
✓ Benchmark certification + registration with Gas Safe
✓ Building regs compliance notification
✓ VAT at 0% (new rate for heating systems — confirm)
✓ Making good any tiling, plastering, painting disturbed

What drives the biggest price swings

Location: Labour costs in London and the south-east. Rural areas also carry higher travel charges.

London +15–25%

Power-flush vs chemical flush: Power-flush is worth it on old systems (8+ years) or visible sludge. Skip it on modern clean systems — chemical flush is fine.

+£200–£500

Brand tier: Worcester/Vaillant/Viessmann vs Ideal/Baxi/Alpha.

+£400–£800

Moving the boiler: New flue, new gas run, new pipework runs.

+£500–£1,500

Gas supply upgrade: If your gas pipe is 15mm and boiler output requires 22mm.

+£300–£900

Scaffolding: Flue above ground-floor ceiling on external wall — sometimes needs scaffold.

+£250–£500

Get 3 quotes — always

Online installers (Boxt, Heatable, iHeat) give fixed-price quotes in 5 minutes with no home visit. They're a good benchmark. Get a third quote from a local Gas Safe engineer on Checkatrade — they often undercut the online quotes by £100–£400 on straightforward jobs.