Top 5 best boilers & brands in the UK for 2025: A complete guide to efficiency and reliability
Replacing your old boiler can prove to be a smart decision, especially if your existing boiler performs poorly or is at the end of its life.
If you are looking to buy the best new boiler on the market, our research has identified the top brands to consider. These are Worcester Bosch, Vaillant, Ideal, Alpha and Viessmann.
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The most highly rated boiler models include the Viessmann Vitodens, Vaillant ecoTEC, Alpha E-tec, Worcester Bosch Greenstar and Ideal Logic.
WhatPrice has analysed customer reviews and online feedback to create the following ultimate guide to the best boilers for 2025.
Top 5 gas boiler brands
Alpha
When you need a new boiler but your budget is tight, Alpha is a brand to consider with its range of combi and system boilers priced well under £1,000. These boilers also have unique technology to promote energy efficiency, including ‘GasSaver’ and ‘FlowSmart’ features.
Ideal Heating
Staying with the affordable boiler range, Ideal boilers offer a typical warranty period of between 4-7 years. Installers praise the ease of installation of Ideal boilers, with space-saving options available for smaller homes.
Vaillant
As one of the premium boiler brands on the market, Vaillant boilers offer exceptional technology and overall energy efficiency. Customers benefit from long warranty periods which are backed by a team of UK-based Vaillant engineers who can provide technical assistance in addition to any boiler cover you may have elsewhere.
Worcester Bosch
A name that needs no introduction, Worcester Bosch boilers have excellent lifespans. Offering gas, oil and LPG boilers, Worcester Bosch has boilers for every fuel type as well as every property size.
Viessmann
While lesser known among consumers, this German manufacturer of boilers is extremely popular within the trade community. 75% of Viessmann reviews on TrustPilot are 5 stars, with users praising aspects such as reliability and ease of use.
Top 5 gas boiler models
Alpha E-Tec Plus NX
The Alpha E-Tec Plus NX combi boiler range has received the prestigious ‘Good Homes Approved’ award. Heating engineers praise it for being a quiet running boiler. This model was recently updated and now boasts improved performance while remaining within the affordable price range.
Ideal Logic Max 30
Compact enough to fit in a kitchen cupboard, the Ideal Logic Max 30 boiler is backed by a 10 year warranty. It offers ease of use for consumers due to its built-in control system.
Vaillant ecoTEC
Dubbed one of Vaillants ‘flagship boilers’ by heating engineers, the Vaillant ecoTEC is one of the brand’s best selling boilers. It’s available in 3 different kW outputs and boasts up to 94% energy efficiency.
Worcester Bosch Greenstar 8000
As the most powerful wall hung boiler produced by Worcester Bosch, the Greenstar 8000 caters towards larger homes. It is also hydrogen ready (20%) and offers a like-for-like swap if replacing existing Worcester Bosch models. The Greenstar 8000 also benefits from intelligent software, endless flue options and wall jigs that can conceal its pipework.
Viessmann Vitodens 100-W
Already rated as one our out best combi boilers the Vitodens 100-W is packed with WiFi-enabled features including instant fault reporting, the Viessmann Vitodens 100-W offers an abundance of user-friendliness. As a hydrogen ready boiler (20%), it helps future-proof your heating and hot water system. The Vitodens 100 is also well built with premium internal components such as a stainless steel heat exchanger.
How we rank the best boilers
We’ve ranked the best boilers by researching customer reviews on various platforms. Crucially, we’ve studied feedback about the overall boiler performance including common areas of complaints or praise.
Where applicable, we’ve also included our own experience of purchasing a new boiler as homeowners or property tenants living in the UK.
💡Top tip: You can contribute your own experiences by submitting how much you paid for your new boiler, or any other work you’ve recently had done. Your information helps us ensure our data is as up to date and as helpful as possible!
Best oil boilers
Grant Vortex Pro 21
The Grant Vortex Pro 21 has won awards for the quality of its heat exchanger which is known to greatly increase hot water performance. The Pro 21 is available in 3 sizes and can achieve an energy efficiency of up to 91%.
Firebird Envirogreen HE
As one of the premium oil boilers on the market, the Envirogreen HE offers superior hot water performance. It benefits from being fully insulated as well as being acoustically designed to ensure quiet operation.
Warmflow Utility U90HE
Offering one of the best affordable oil boilers, the Warmflow Utility U90HE is an A-rated condensing boiler. Backed by a 7 year warranty, it’s a great choice for homes with more than one bathroom.
Worcester Bosch Greenstar Danesmoor Utility 12/18kW
As the highest rated oil boiler made by Worcester Bosch on a leading plumbing merchant website, this boiler model is best associated with having excellent reliability. Recent refinements of this model have also resulted in a reduced weight. Kitchen, utility or external models are available.
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Online installers such as WarmZilla, Heatable, iHeat & BOXT have become very popular in recent years and for good reason, they offer a fast and efficient way of pricing and arranging a boiler replacement all through their website.
Best electric boilers
ACV Etech W Wall Mounted Electric System Boiler
Requiring only minimal ventilation, the ACV Etech can not only be installed anywhere but is also compatible with traditional radiators or modern underfloor heating systems.
Electric Heating Company Comet PV System Boiler
Providing an incredible 100% energy efficiency and zero carbon emissions, the Comet PV is one of the most innovative electric boiler makes on the market. It comes complete with a range of features including smart home technology.
Elnur Mattira MAC15 Electric Combi Boiler
Automatically modulates in response to heating or hot water demand to deliver maximum efficiency. Geared towards single bathroom properties, the MAC15 comes with an intuitive digital display for ease of use.
Heatrae Sadia Electromax 9kW Electric Flow Boiler
As a top rated Heatrae Sadia electric boiler model, the Electromax offers fully controllable heating. It can also be programmed to cater to different energy tariffs to reduce energy bills. It’s backed by an impressive 10 year warranty.
Boiler efficiency explained
| Rating | Efficiency |
|---|---|
| A | 90%+ |
| B | 86-90% |
| C | 82-86% |
| D | 78-82% |
| E | 74-78% |
| F | 70-74% |
| G | Below 70% |
Boiler energy efficiency runs on a scale of A to G.
Similar to other features found elsewhere in your home such as your windows or appliances, boiler efficiency ratings denote its overall performance.
Simply put, if a boiler is efficient, it means it requires a minimal amount of energy to heat your water and radiators. As a result, it will generally be cheaper and greener to run.
Since April 2018, all new boilers must achieve an A rating for energy efficiency.
However, if your boiler was installed prior to 2018, it is likely lacking in efficiency. The boilers likely to be most inefficient are those heading towards the end of their lifespan, i.e. at least 10 years since they were installed.
Boiler reliability
When comparing new gas boiler prices, the reliability of both the brand and boiler make should be top of the agenda.
For new or existing boilers alike, there can be some common factors which impact reliability:
- Boiler age: Older boilers are more likely to become unreliable. Upgrading to a new boiler ensures your property benefits from the latest in boiler technology. If your boiler is over 10 years old, it will benefit the most from an upgrade to a new and more reliable model.
- Maintenance: Boilers require regular maintenance to keep them working safely and efficiently. A lack of maintenance is a common reason for boiler failure. Skipping your annual service may also invalidate the manufacturer’s warranty.
- Flue system: During a boiler service, your boiler technician will inspect the flue outside of your property. If the flue has become damaged or is corroded, the boiler may experience issues and will have reduced efficiency.
Boiler warranties and guarantees
What is a boiler warranty?
A boiler warranty specifies the length of time your boiler will be covered by the manufacturer in case of genuine fault. So long as your boiler is still within the warranty period and you have had the boiler serviced as required, the manufacturer will be obliged to repair the boiler.
Boiler warranty periods vary anywhere from 1 to 10 years on average. As you might expect, boilers with a shorter warranty tend to be on the cheaper end of the scale owing to their typically shorter lifespans and overall higher maintenance costs.
What is the difference between a warranty and guarantee?
In essence, a boiler guarantee and a boiler warranty are describing the same things. The only real difference is that a boiler guarantee outlines a promise from the manufacturer that they will repair your boiler for a fixed time frame regardless of the fault cause.
Some brands (i.e. Worcester Bosch) only offer boiler guarantees rather than boiler warranties. The reason for this is because a guarantee can seem more appealing to customers, since it means they will repair or replace your boiler for a set period of time. In contrast, a warranty often comes with limitations about the faults that will be repaired, along with how long repairs will be offered for following the installation.
Are there any boiler brands to avoid?
Apart from one exception, it’s not usually the case that any single boiler brand should be avoided. However, there are some specific boiler models that have been poorly rated on various review platforms.
- Ferroli: Across the board, Italian boiler manufacturer Ferroli rates very poorly due to high failure rates along with frequent maintenance issues.
- Baxi’s 400 Combi 2: Due to frequent problems reported by installers, Baxi revamped its 400 Combi 2 to the 2.1 model soon after its initial release. However, the Combi 2 remains available for purchase as it was not withdrawn from the market.
- Vokera’s Vision 30c Combi Gas Boiler: Due to having some of the highest number of user complaints, the Vision 30c boiler by Vokera also makes it onto the list. Common issues arise from so-called ‘inferior’ parts leading to frequent malfunctions and endless error codes.
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Best new boiler UK FAQs
Thinking about purchasing a new boiler and have some questions? We’ve answered some of the most popular queries below.
For anything else, such as our central heating boiler price information, be sure to check out our other boiler content. Here, you’ll find our latest price guides and installation tips.
What type of boiler should I get?
In short, the type of boiler that is best for your specific property and overall needs. You should consult a trusted heat engineer for further advice if you are unsure.
Combi boilers are the most popular type of boiler as they can provide heating and hot water on demand. They can run on gas or electricity and there is no need to have a tank in the loft.
System boilers require excellent mains pressure to run, although the water must be heated up before it is used. They are extremely energy efficient and a great choice for homes with multiple bathrooms.
Conventional boilers are ideal for properties that have low water pressure with a need to deliver hot water to multiple locations at the same time. While one of the cheapest boiler types to install (like-for-like swaps), if the hot water runs out then you will need to wait for it to reheat.
Finally, if you have the budget then a heat pump boiler offers the latest technology and is also exceptional for energy efficiency.
Why is boiler efficiency important?
Inefficient boilers are more expensive to run. Therefore, upgrading to a new boiler can reduce your energy bills.
An efficient boiler also makes your property more environmentally friendly.
How often should I service my boiler?
Most manufacturers require the boiler to be serviced annually as part of the warranty agreement. However, even if the boiler is no longer under warranty, you should still schedule a service by a qualified heating engineer every 12 months.
Regardless of when your last boiler service was, if you are currently experiencing any issues with your boiler, then you should arrange to have it inspected by a qualified heating engineer without delay.
How can I improve my boiler’s efficiency?
Depending on the age of your boiler, it may be possible to increase its efficiency by having a heating engineer perform some maintenance. Common tasks include bleeding the radiators, using a central heating inhibitor, insulating any pipework and also adjusting the boiler pressure.
However, if you have an older boiler, it may be more effective to upgrade your boiler. Taking the opportunity to make any other required updates to the energy efficiency of your home such as upgrading any draughty windows can also maximise your energy bill savings. That’s because when your home is energy efficient, your boiler doesn’t have to work as hard to heat your home.
What are the signs that I need a new boiler?
If you are the homeowner who installed the boiler, then you will typically know when it’s time for a new boiler based on how long ago it was installed. Typically, this is around the 10-15 year mark.
For tenants or homeowners who moved into their property after the current boiler was installed, there are some tell-tale signs to look out for. This includes frequent boiler breakdowns, or a generally inefficient boiler (i.e. difficulty achieving hot water).
During your annual boiler service, your technician will also advise if your boiler is due for replacement. Once your boiler is deemed beyond economic repair or if it is condemned, then a boiler replacement will be required immediately.
How do I find a qualified heating engineer?
As a minimum, the engineer should be on the Gas Safe Register to be able to legally work on any gas appliance in your home.
However, for additional peace of mind, you may also want to look out for engineers who have relevant industry accreditations such as CIPHE or WIAPS. A select number of heating engineers in the UK are also Trading Standards Approved.
Of course, it is also essential to do your research before hiring a plumber to install a boiler by reading customer reviews. You may also be able to discover the best plumbers local to you by asking for recommendations from friends and family.