Boilers
Best Combi Boilers 2026: Models, Prices and Where to Buy
The best combi boilers for 2026 from Worcester Bosch, Vaillant, Ideal, Baxi and Viessmann: boiler-only prices, warranties, who each suits and where to buy.
Published 3 October 2026
There is no single best combi boiler. There is a best combi boiler for your home, your hot water use and your budget. This guide walks through popular 2026 models from five of the best-known brands, what each one costs to buy as a boiler on its own, what the warranty really depends on, and where you can buy one.
All prices below are for the boiler unit only, including VAT, as listed by UK merchants in early October 2026. They do not include the flue, filter, controls, parts or fitting, except where a merchant only lists a bundle, which we point out. Merchant prices change often, so treat them as a guide and check on the day.
How Do You Compare Combi Boilers Fairly?
Before looking at brands, it helps to know what actually separates one combi from another:
- Hot water output (kW) and flow rate (litres per minute). A combi heats water as you use it, so the flow rate decides how well a shower runs, and whether two taps can run at once.
- Warranty length and its conditions. The headline figure usually depends on who fits the boiler, whether a magnetic filter goes in, and whether it is registered and serviced every year.
- Fit with your home. The right size, a flue position that works, and controls that meet Building Regulations matter more than the badge on the front.
If you are not sure whether a combi is right for you at all, start with our guide to combi, system and conventional boilers, and see what to look for in a new boiler.
Worcester Bosch Greenstar 4000
Merchant price: around £1,290 to £1,510 at Screwfix in October 2026, depending on output (25kW and 30kW hot water versions).
Warranty: Worcester Bosch lists 7 years as standard on the Greenstar 4000, 8 years when fitted with a Greenstar System Filter, and 10 years when fitted by a Worcester Bosch Accredited Installer with a Greenstar System Filter. One merchant listing we checked showed a shorter guarantee, which is a good reminder that the length you get depends on how the boiler is fitted and registered, not on the box.
Who it suits: flats, terraces and smaller semis with one bathroom, where you want a well-known brand at a mid-range price.
Worcester Bosch Greenstar 8000 Life
Merchant price: around £1,770 (30C) to £2,200 (40C) at Screwfix in October 2026.
Warranty: Worcester Bosch lists 8 years as standard on its Greenstar 8000 range, 10 years with a Greenstar System Filter, and up to 12 years when fitted by an accredited installer with a Greenstar System Filter. Extended guarantees are not available with the smaller System Filter Micro.
Who it suits: larger homes and busier households. The 30C is listed with a hot water flow rate of 11 litres per minute, and the higher outputs give more.
Vaillant ecoTEC plus
Merchant price: around £2,020 for the ecoTEC plus 832 at City Plumbing in October 2026. City Plumbing also sells bundles with a horizontal flue and Vaillant Boiler Protection Kit at around £2,240 (826) to £2,700 (840).
Warranty: Vaillant gives 5 years as standard, extendable to up to 10 years when the boiler is fitted by a Vaillant myREWARDS installer and registered with a Vaillant Boiler Protection Kit (its filter).
Who it suits: most homes. Vaillant says the ecoTEC plus can turn down to 16% of its maximum power, which suits well-insulated homes where the heating rarely needs full output.
Vaillant ecoTEC exclusive
Merchant price: we could not confirm a current public merchant price for the ecoTEC exclusive in October 2026. Ask for it as a separate line in any quote.
Warranty: up to 10 years when fitted by a Vaillant myREWARDS installer and registered with a Vaillant Boiler Protection Kit.
Who it suits: homeowners who want Vaillant’s premium model. Vaillant describes it as carrying its Green iQ mark for efficiency and lists it with a 27kW heating output.
Ideal Logic Max Combi2
Merchant price: around £1,350 (C24) to £1,660 (C35) at Screwfix in October 2026.
Warranty: Ideal lists a 10 year parts and labour warranty when the boiler is registered within 30 days of installation and serviced every year.
Who it suits: good value for flats and family homes. Ideal lists hot water flow rates of 9.9 litres per minute (C24), 12.4 (C30) and 14.5 (C35).
Ideal Vogue Max Combi
Merchant price: around £1,570 (26) to £1,900 (40) at Screwfix in October 2026. City Plumbing lists the C32 with an Ideal system filter at around £1,830.
Warranty: 10 years, rising to 12 years when fitted and serviced by an Ideal Max Accredited installer, registered within 30 days and serviced every year.
Who it suits: homes that want strong hot water performance. Ideal lists 10.6 litres per minute (C26), 13.1 (C32) and 16.4 (C40).
Baxi 600 Combi 2
Merchant price: around £980 (624) to £1,260 (636) at City Plumbing in October 2026.
Warranty: Baxi lists a 7 year parts and labour warranty, with terms and conditions.
Who it suits: tighter budgets, flats and smaller homes where a reliable, straightforward boiler is the priority.
Baxi 800 Combi 2
Merchant price: for the 30kW model, around £1,630 at City Plumbing (bundled with a horizontal flue and Adey Micro2 filter) and around £1,930 at Toolstation for the boiler on its own, in October 2026. That spread shows why comparing like with like matters.
Warranty: Baxi lists a 10 year parts and labour warranty, provided the Adey Micro 2 filter is installed and registered at the same time as the boiler.
Who it suits: homeowners who want a longer warranty from a UK-built boiler without paying top-tier prices.
Viessmann Vitodens 100-W
Merchant price: around £1,530 to £1,690 at Screwfix in October 2026, across the 26kW, 30kW and 35kW hot water versions.
Warranty: Viessmann lists 7 years as standard, upgradeable to 10 or 12 years. The installation must be registered with Viessmann within 30 days, otherwise it falls back to a basic 2 year warranty.
Who it suits: homeowners who like a stainless steel heat exchanger and built-in Wi-Fi, both listed on the Screwfix product page. Viessmann also makes the Vitodens 050-W (7 years, upgradeable to 10) and the 111-W.
Where Can You Buy a Combi Boiler?
You have two routes:
- From a merchant. Screwfix, Toolstation, City Plumbing and Travis Perkins all list boilers online, and plumbers’ merchants such as Plumb Center and Graham stock them too. Check whether the listing includes the flue and filter, as many do not.
- Supplied by the installer. This is the usual route. The engineer orders the right boiler, flue, filter and controls together, and is responsible if a part is wrong.
Buying the boiler yourself can look cheaper, but there are catches:
- Many installers will not fit a customer-supplied boiler. They cannot guarantee where it came from, how it was stored, or that it is the right model for your home.
- Extended warranties usually need an accredited installer. The longest warranties from Worcester Bosch, Vaillant and Ideal depend on the boiler being fitted by an installer in their scheme, with the right filter, and registered within the deadline (30 days for Vaillant, Ideal and Viessmann).
- Annual servicing is part of the deal. Most warranties require a yearly service by a Gas Safe registered engineer. See how often you should service your boiler.
- The boiler is only part of the cost. The fitting is quoted separately, after the engineer has seen the job. We explain how that works in new boiler cost explained.
Which Combi Boiler Is Best for You?
As a rough guide:
- Tight budget, one bathroom: Baxi 600 Combi 2 or Ideal Logic Max.
- Mid-range, strong warranty: Ideal Logic Max, Baxi 800 Combi 2, Worcester Bosch Greenstar 4000 or Viessmann Vitodens 100-W.
- Bigger homes or higher hot water demand: Worcester Bosch Greenstar 8000 Life, Ideal Vogue Max or Vaillant ecoTEC plus.
If more than one bathroom is often in use at the same time, a combi may not be the right type at all. A system boiler with a cylinder can be the better answer, and a good engineer will tell you so.
Get a No-Obligation Quote
For a no-obligation quote, call 07360 268948 or send photos of your current boiler on WhatsApp, and we’ll put you in touch with a local Gas Safe registered engineer who can recommend the right model for your home. Find out more about boiler replacement in the TW area.