The Best Combi Boilers for Your Home (2018)

What is a Combi Boiler?

The combi boiler, or combination boiler, is the most common type of boiler system found in British homes today. Providing heat and domestic hot water on demand, without the need for extra space for separate storage tanks and cylinders, the combi is popular for its functionality, low-cost installation and use.

Whether it’s fueled by electric, gas or oil fired, the combi boiler can be a reliable source of heat for your home for years after its installation – but choosing the right combi boiler is vital. Making an unwise investment can lead to higher bills, unreliable water flow and increased expenditure on troubleshooting and problem-solving.

As it’s such an important investment, deciding what combi boiler to buy can be a difficult decision, especially if you’ve not seen as many boiler installations as we have. In an effort to make the information surrounding boilers a little clearer, we’ve come up with the following guide to the best performing boilers for your home.

Why Choose a Combi Boiler?

A combi boiler is a high-efficiency water heater and central heating system in a single unit. The cold water mains is directly connected to the boiler, which is heated on demand when a hot water tap is opened through an independent heat exchanger. This eliminates the need for additional space for an extra storage tank, meaning you not only save on installation costs but also space. Although that isn’t the only benefit of a combi boiler.

Benefits of Installing a Combi Boiler

There are a lot of reasons why you should get a combi boiler, among them, are:

  • Hot water on demand
  • A neat, self-contained system which eliminates the need for extra cylinders or tanks
  • Maintenance is in one place
  • Smaller carbon footprint than larger dated storage systems
  • No need for additional pumps to pressurise the water as the hot water is driven by the mains


The Best Combi Boiler Manufacturers

Due to their popularity in the domestic market nowadays, most boiler brands and manufacturers have a wide range of combi boilers. But when buying a new boiler, you have to be aware that some boilers, and manufacturers, are better than others.

Boilers aren’t always a one size fits all solution, and the leading combi boiler on the market may be excellent, but won’t necessarily meet all the specific needs of your home. We’ve worked in the industry for long enough now that we know what works and what doesn’t.

After working in various homes over the years, we’ve come to advocate only a few boiler manufacturers for their value, performance and longevity.

Worcester Bosch boilers have been installed in over 1 million homes in the UK. In 2017, the largest independent consumer body in the UK, Which? determined that Worcester Bosch boilers were the most reliable on the market from a survey of over 10,000 consumers and 200 heating engineers.

All Worcester boilers are covered by up to a 10-year guarantee, and their commitment to both their boilers and their customer service means that only accredited plumbers can install their boilers.

This, amongst other reasons, is why we’re an accredited Worcester Bosch installer, and why they are one of only a few manufacturers we actively advocate.

Even though Worcester is one of the best on the market, it still doesn’t mean that you shouldn’t take the time to sort through which model will work best for you. If you want to know which Worcester combi boiler you should be buying for your home, read on.

The Best Combi Boilers For Your Home

Worcester 34Cdi Classic Combi

Best Combi boiler for Homes with 3 bedrooms +

Worcester 34Cdi Classic Combi Boiler

Worcester 34Cdi Classic Combi Boiler

The 34Cdi Classic combi boiler is one of the most popular choices for medium to large properties for its capacity to deal with a high demand for heating and hot water.

Coming with the 10-year boiler guarantee when fitted with Worcester Bosch Greenstar filter and comfort controls, this particular model also has built-in frost protection and is fully ERP compliant.

Although this boiler works with a natural gas supply, it does also come as an LPG option.

Why Should You Buy?
  • Save up to 20 – 30% on your heating bills by switching to this combi boiler. Rated as a SEDBUK band A-rated boiler, the 34CDi operates at over 90.1% efficiency – one of the highest energy efficiency levels on the market.
  • With a vastly improved heating output of 30kW and an improved flow rate of 14.3 litres per minute at 35 degrees Celsius, this boiler will comfortably allow you to run multiple hot streams at once.
  • Worcester have also invested heavily in reducing the standby electrical output by approximately 60%. The Boiler operates at just 3.5W when on standby.
  • It’s stylish, clean and modern and can be easily fitted in fairly small spaces. The pipework can even be hidden from view using a wall mount.
  • Parts are easy to find, and it is easy to maintain and fix.


Worcester 30i Combi

Best Combi Boiler for Homes on a Budget

Worcester 30i Combi Boiler

Worcester 30i Combi Boiler

The 30i model is built with medium sized properties (2-3 bedrooms, 1 bathroom) in mind. Although equally as efficient as the other A-rated condensing models on the list, the fantastic price point of the 30i makes it a standout for those shopping on a budget, without wanting to negotiate on performance.

This model comes with a 5-year guarantee as standard and is fully compliant with the EU’s ErP Directive.

Why Should You Buy?
  • Output of 25kW and hot water flow rate of 9 litres per minute, allowing for an excellent heating performance and speedy heat up time.
  • This boiler is easy to service. Components, including the expansion vessel, are easily accessible, therefore easier to repair or replace.
  • Comes with an integrated Siphon that combats frozen condensate internally, so no need to purchase an extra part come winter time.
  • The interface is simple and easy to use with a scrolling text display. This enables you to communicate more accurately with engineers.


Worcester 30Cdi Classic Combi Controls

Worcester 30Cdi Classic Combi Controls

Worcester 25i Combi

Best Combi Boiler for 1 Bedroom Flat

Worcester 25i Combi

Worcester 25i Combi

The 25i is perfect for those with smaller properties, such as small houses with 1 bathroom. With a low price point, SEDBUK A rating and high-performance quality, the 25i allows you to compromise on space, not quality.

This model comes with a 5-year guarantee as standard and is fully compliant with the EU’s ErP Directive.

Why Should You Buy?
  • Quick heat up times and great performance with a 25kW and 9 litre per minute flow rate.
  • Comes with a built-in CondenseSure Style Siphon, eliminating the need to buy an additional part for your boiler to combat frozen condensate.
  • Easy to use adjustable heating controls. Now, you can fine-tune the temperatures of your hot water and central heating controls to a level to suit you. Also compatible with the Worcester Wave, which enables you to control your heating remotely over an internet connection.


When pricing up a new combi boiler to buy, make sure you ask for the installation price, not just the price for the boiler. As fitting and installing a gas boiler by yourself is not something you should be doing unless you’re a qualified Gas Safe Registered engineer.

Don’t join the 52% of Bristol homes already at risk from unsafe gas work. Make sure your home is never at risk from faulty gas work by hiring a Gas Safe Registered engineer, whose competence and qualifications are regularly checked by the official Gas Safe Register body. Ensuring your home is never at risk from faulty gas work.

If you’re unsure how to check whether your engineer has the right qualifications, read our guide to checking proper credentials here:

For more information on anything to do with your central heating system, from boiler servicing to boiler repairs, take a read of our blog, or don’t hesitate to contact one of our expert (and Gas Safe Registered) engineers for a chat on 01179 093 967