How much does a new boiler cost in London in 2026?

If you're shopping for a new boiler in London right now, you've probably noticed something unhelpful: every quote you get back is wildly different. £2,500 from one. £4,800 from another. £7,200 from a third. For — supposedly — the same job.

This guide explains where those numbers actually come from, what changes the price the most, what a fair price looks like in 2026, and how to spot when you're being quoted for things you don't need.

Written by Ilir Nuredini, a qualified plumber installing boilers across London since 2004.

The quick answer

For most London homes in 2026, expect to pay roughly:

These are realistic 2026 London prices for installations done properly — by a qualified gas engineer, with a magnetic system filter, an inhibitor refill, and a manufacturer warranty registered in your name.

If a quote is significantly below the bottom of these ranges, something is being cut. Usually labour quality, sometimes the warranty, occasionally both.

What goes into the quote

A boiler quote is made up of five things. Different installers weight them differently, which is the main reason you get such different numbers.

1. The boiler itself

Trade prices for the boiler vary widely. A basic Ideal Logic combi might be £700 trade. A Vaillant ecoTEC plus is around £1,200. A Worcester Bosch Greenstar is £1,300–£1,500 depending on the model. Premium brands cost more — but they also tend to last longer and come with better warranties.

2. Ancillary parts

A proper installation includes more than just the boiler. You should expect:

• A magnetic system filter (Adey MagnaClean, Spirotech Spirovent, Worcester Greenstar System Filter). Trade cost £80–£150. Catches iron oxide before it kills the heat exchanger. This should not be an upsell — it's basic practice in 2026.
• Inhibitor (Sentinel X100 or similar). Trade cost £20–£30. Stops corrosion in the system. Mandatory under building regulations.
• Flue parts, gas pipework upgrades if needed, condensate run, isolation valves.
• Flue gas analyser test report at commissioning.

If a quote leaves the magnetic filter out, ask why. The answer is almost always "to bring the price down" — and you'll regret it within five years.

3. Labour

Labour is the biggest single line on most quotes. London labour rates in 2026 are roughly £350–£500 per day for a qualified gas engineer working alone. A combi swap takes one full day. A system-to-combi conversion takes two. A first-time install takes three to five depending on the property.

This is the line where the difference between a competent installer and a rushed one shows up most. A boiler installed properly in eight hours is worth more than one bashed in over four — every time.

4. Power flush or chemical clean

If your existing system is more than ten years old and has never been flushed, you almost certainly need either a power flush or a chemical clean before fitting the new boiler. Pumping clean water through a sludged system into a new heat exchanger is a fast way to kill it.

Cost: £400–£700 for a power flush, £150–£250 for a chemical flush. Honest installers will quote this separately and explain why. Dishonest ones either skip it (and shorten the new boiler's life) or hide it inside the install price so you can't compare quotes properly.

5. The warranty

Worcester Bosch and Vaillant both offer up to 12-year warranties — but only when fitted by an accredited installer. Worcester's Accredited Installer scheme requires the engineer to register the warranty in your name on the day of install. If a non-accredited installer fits a Worcester boiler, you typically get the standard 5-year warranty, not 12.

This matters more than people realise. A Worcester Greenstar with a 12-year warranty is genuinely a different proposition from the same boiler with a 5-year warranty — even though the boiler is identical.

Cost by brand

Worcester Bosch

The default premium choice. Reliable, well-supported, parts available, engineers know them inside out. Greenstar 8000 Style is the high-end model, Greenstar 4000 is the mid-range. Up to 12-year warranty when fitted by a Worcester Accredited Installer.

London installed cost in 2026: £2,800 – £4,500 for most domestic combi installs.

Vaillant

Worcester's main competitor and arguably better engineered, particularly the ecoTEC plus and ecoTEC exclusive ranges. Slightly quieter than Worcester, very reliable, similar 10-year warranty when fitted by a Vaillant Advance installer.

London installed cost in 2026: £2,700 – £4,400.

Ideal

The best of the mid-range brands. Ideal Logic and Logic Max are popular in London for their balance of price and reliability. 10-year warranty available on top-spec models when fitted by an Ideal Max Accredited installer.

London installed cost in 2026: £2,200 – £3,400.

Baxi

Solid mid-range, particularly for system and regular boilers. The Baxi 800 range is well-regarded. Generally cheaper than Worcester or Vaillant for similar specs.

London installed cost in 2026: £2,100 – £3,200.

Viessmann

Premium German engineering. Very reliable but parts can be slower to source than Worcester or Vaillant in the UK, which matters if you ever need a repair. Up to 12-year warranty.

London installed cost in 2026: £3,000 – £4,800.

Cost by property type

1-bed flat

Combi swap (replacing one combi with another in the same location): the simplest job. £2,200–£3,200 typical.

If the flat is in a converted house with shared flue or unusual access (e.g. boiler in a kitchen cupboard you can't get a stepladder into), expect £200–£400 more.

2–3 bed terrace

The most common London install. £2,500–£3,800 for a combi-to-combi swap.

If you're moving from a system boiler with hot water cylinder to a combi, add £700–£1,200 for cylinder removal, pipework alterations, and new combi flue routing.

4+ bed Victorian terrace or detached

For larger London houses with multiple bathrooms, you need a properly sized combi or — more often — a system boiler with cylinder. £3,500–£5,500 for a system swap, £4,500–£6,800 for a system-to-combi conversion.

Critically: if you have two or more bathrooms used simultaneously, a combi may not be the right answer at all. A system boiler with cylinder gives you hot water at multiple taps without pressure dropping. Anyone quoting you a combi for a four-bath house without checking flow rate is doing you a disservice.

Why London is more expensive than the rest of the UK

Three reasons:

1. Labour rates. A gas engineer in London earns more than one in Birmingham or Newcastle. That's just the cost of living and operating here.
2. Property complexity. London has more old buildings, more flats with shared flues, more listed properties, more access challenges than anywhere else in the UK.
3. Disposal and parking. Disposing of an old boiler in London costs more (limited skip access, more borough restrictions). Parking on a job site often costs the engineer £20–£60 per day in permits and meters.

A like-for-like job in London usually costs 15–25% more than in the regions. That's not unfairness — that's reality.

Grants available in 2026

Boiler Upgrade Scheme (BUS)

The UK government's Boiler Upgrade Scheme pays £7,500 toward the cost of an air source heat pump (or £5,000 for a biomass boiler). It does not apply to gas boilers.

If you've been told there's a grant for a new gas boiler, that's incorrect. There isn't. There hasn't been since the Green Homes Grant ended in 2021.

ECO4

The ECO4 scheme provides funding for boiler replacement for households on certain benefits or in low-income properties. It's administered through energy suppliers and usually fits low-cost mid-range boilers, not premium installs.

Heat pump grant route

If you genuinely want to switch from gas to a heat pump, the BUS grant of £7,500 brings the cost of a typical air source heat pump install down from £12,000–£18,000 to £4,500–£10,500. For older Victorian properties without heat-loss improvements first, this is often a poor financial decision — but for modern, well-insulated houses, it can make real sense.

How to get an honest quote

Three things to ask any installer:

1. Can I see your qualifications and insurance? Ask to see the actual certificates — a real pro will not hesitate. Don't take their word for it.
2. Are you an accredited installer for the brand you're quoting? This matters for the warranty length. A Worcester boiler from a non-accredited installer is the same boiler with half the warranty.
3. Show me the heat-loss calculation for the property. Anyone sizing a boiler without doing this is guessing. The wrong-sized boiler is the most common cause of cold radiators and short boiler life.

If you get satisfactory answers to all three, you have a real installer. If you get hedging or "we don't usually do that," walk away.

Frequently asked questions

Why are boiler prices so different between installers?

Three reasons: brand and accreditation level, the actual quality of the work being done, and what's being included silently (or excluded silently). The cheapest quote almost always cuts something — usually the magnetic filter, the power flush, or the warranty registration.

How long should a new boiler last?

Twelve to fifteen years for a Worcester or Vaillant fitted properly, serviced annually, in a clean system. Less if installed in a sludged system without flushing, or if oversized so it short-cycles.

Should I pay a deposit?

For materials yes, normally 30–50% on larger jobs. For labour no — that should be on completion. Anyone asking for a full payment up front is a red flag.

What's the cheapest way to replace my boiler?

Don't replace it if you don't have to. Many older boilers can be repaired economically for years longer. If yours is over 12 years old and has had a major component fail, replacement usually wins. Otherwise, repair.

What about extended warranties?

Extended manufacturer warranties (Worcester 12-year, Vaillant 10-year) are essentially insurance. They're free at the point of install if your installer is accredited, and they're worth having. Third-party extended warranties sold by some installers separately are usually overpriced.

Can I install a boiler myself?

No. Gas work in the UK requires qualification. DIY gas work is illegal and dangerous. Carbon monoxide poisoning from amateur boiler installs kills people every winter. Don't do it.

How much should the call-out fee be?

For a new boiler quote, there should be no call-out fee. Quotes are free and no-obligation in this trade — anyone charging for a quote is unusual.

Get a free no-obligation quote

If you'd like an honest assessment of what your London property actually needs, get in touch. No pressure, no upselling, no commission deals.