Best Combi Boilers in the UK (and Which to Avoid)

We’ve looked at many areas to produce this top 10 with a particular focus on the following.

Top boiler brands: We include boilers from brands Worcester, Viessmann, Ideal, Vaillant, Baxi & Alpha, which are all known for producing reliable boilers at different price points.

Price: Here at WhatPrice we specialise in ensuring homeowners get the best deal. That’s why we’ve scoured the internet and listed below how much you can expect to pay for a new gas boiler, based on a like-for-like replacement.

Long warranties: Every boiler we include must come with at least 7 years warranty, many have much longer but always check that your installer can supply the boiler with the maximum warranty available, they may have to fit the brands filter or be an accredited installer.

High efficiency: We all want the most efficient combi boiler, right? It saves money and helps the planet. That’s why all the boilers in our top 10 are A-rated to ensure you reap the benefits.

Customer support: We’ve spoken to engineers who can all vouch for the boiler brands we recommend, plus we’ve checked all the boilers here are backed by a UK nationwide support network.

A lower cost option that’s suitable for smaller homes and flats. It’s compact enough to fit inside a kitchen cupboard and Quiet Mark certified so won’t wake you in the middle of the night.

Available in two outputs of 25 & 30kW, the lower output of the two will be suitable for flats and smaller sized homes with one bathroom, anything larger then opt for the 30kw model.

This is a popular and reliable model from a big brand at a lower cost, if your budget allows however go for the Worcester 4000 which is slightly more efficient and comes with a longer warranty.

The Greenstar 4000 is the most popular combi boiler from Worcester for good reason, it’s efficient, compact, quiet and packaged in a modern sound insulated case that looks pretty good on your wall.

Only slightly more expensive than it’s smaller sibling, the Worcester Greenstar 2000, its additional hot water output makes it a worthwhile upgrade if you’re considering the Worcester 2000 vs Worcester 4000.

The boiler is also popular with Installers, it’s easy to fit and to maintain with front access to all components. It’s a good choice for anyone looking for a reliable combi for a small to medium sized home.

The Vitodens 050-W is known for its high efficiency, compact design, and quiet operation. It comes with smart technology features, including Wi-Fi connectivity for remote control via a smartphone and remote support.

Supplied in 25kW & 30kW models the Vitodens 050 combi boasts 7 years warranty and includes a stainless steel heat exchanger as standard. Being hydrogen ready you’ll be future proofed for changes in your gas mixture should this happen in your area.

A very compact and quiet boiler with a very user friendly control panel, it’s perfect for small houses and flats as it can fit inside a kitchen cupboard.

The Vitodens 100-W is one of the most popular models due to its exceptional build quality and efficiency. It’s cost being slightly higher than most is justified with the use of high quality components such as a stainless steel heat exchanger, which enhances durability and efficiency.

It’s smart WiFi integration enables remote support by the manufacturer ensuring minimum downtime in the event of a breakdown.

Available in 3 outputs the Vitodens 100-W combi boiler is best for small to medium sized homes with 1 or more bathrooms.

Vaillant’s EcoTec Pro boilers offer reliable performance with a focus on energy efficiency and lower emissions. Manufactured in Vaillant’s Derbyshire plant it’s another boiler, similar to Viessmann, that contains a Stainless Steel heat exchanger, this ensures longevity and superior heat transfer.

Not only is this boiler future proofed being hydrogen ready it’s also compatible with Vaillant’s aroTHERM plus air source heat pump, making it the perfect entry into renewable systems.

Available in 3 output options this Vaillant combi is a great option for small to medium-sized homes.

The EcoTEC Plus is one of Vaillant’s premium combis, offering higher efficiency, smart connectivity, and excellent British build quality.

It’s a powerhouse of heat available in 4 outputs up to 40 kW making it our best combi for larger homes with high hot water demands.

Like its smaller sibling it’s fitted with a stainless steel heat exchanger and smart controls. It’s a favourite of heating engineers nationwide and for good reason. It carries a higher cost than most combis but you won’t go wrong choosing this boiler.

The Ideal Vogue Max is available in 3 versions up to 40kW in output, making it the best choice for larger homes. It’s simple to fit and use with rotary dials and an LCD display.

With up to a 12-year warranty, this Vogue Max is a reliable unit backed by a company with a good track record in customer support. It also comes with an Ideal filter in the box and stainless steel heat exchanger as standard.

The Vogue Max combi boiler is a solid choice and won’t break the bank.

The smallest combi in our list, the Ideal Logic+ is the best combi for kitchen cupboards and tight spaces. It’s also incredibly efficient and quiet, what’s not to like?

With an easy to use colour screen and simple interface the Logic plus is designed and made in the UK, specifically for UK homes. Whilst being very compact the boiler can also be fully serviced from the front, so you won’t need your kitchen dismantling should something go wrong.

Available in 3 models (824 Combi 2, 830 Combi 2 & 836 Combi 2) the 800 series is a lightweight and compact boiler suitable for installation within kitchen cupboards.

The Baxi 800 contains a built in filling loop, brass fluid fittings (most others are plastic) and a stainless steel heat exchanger which ensures rock solid reliability. On the outside you get no-frills analogue pressure gauge, rotary dials and an LCD display for ease of use. Inside the box you’ll get an Adey Micro2 magnetic system filter which is an outstanding filter.

Engineer feedback for this boiler is very positive, they say it’s easy to fit, service and quiet in operation. Its compact size is a real bonus for houses with little wall space for a boiler.

The Alpha NX combi is the best value option we’ve found, providing high efficiency and reliability at a lower price point. It comes with a 7-year warranty as standard but shopping around we found it available with a whopping 11-year warranty.

It comes with a stainless steel heat exchanger and is available in two models of 28 & 33kW outputs making it the best combi boiler for small and medium sized homes.

You may wonder what the support would be like for such a cheap combi, but looking on Trustpilot you’ll see Alpha Heating perform very well with a score of 4.6/5 from over 6,400 reviews.

This is a simple, straightforward and efficient boiler at a great price, you can’t go wrong.