HomeServe Membership Limited is a credit broker, not a lender. Barclays Partner Finance acts as the lender. If you choose a credit option, Help-Link UK Limited trading as HomeServe will receive commission from Barclays Partner finance which is a fixed percentage of the total loan amount. For more information, contact Help-Link UK Limited. The approval of your application depends on your financial circumstances and borrowing history, so do the terms you may be offered. Other finance, deposit and term options are available. Access to Finance is not guaranteed and credit is subject to status, affordability assessment and credit checks. Minimum spend and eligibility criteria applies.

Complete guide to a new combi boiler installation

Combination boilers or “combi” boilers are one of the most popular choices of home boiler systems within the UK. True to their name sake, these heating systems combine efficient water heating with powerful central heating in one to provide households with on demand hot water and heat.

Our A-rated gas combi boilers are a great choice for most homes. They’re typically easy to install, compact, and available in a range of sizes and outputs. Our boilers are also compatible with a selection of fuel sources, so whether you’re in need of a LPG, oil or gas combination boiler we have an extensive range of boilers that should be able to suit your needs.

Try our free quote service today if you’re interested in getting a new combi boiler installation or if you’re facing any trouble with the one you have installed. Our sales team will be in touch in a jiffy.

Quick navigation links





What is a combi boiler & how does it work?

What is a combi boiler? A gas combi boiler is designed to be a highly-efficient means of concurrently heating the water within your home and providing central heating. Combination boilers control your whole central heating system directly from one, compact unit and provide a range of advantages based on factors such as space, energy and costs.

One of the main features of these boilers is their ability to provide instantaneous hot water without water tanks or cylinders, making them typically easy to install and less likely to take up excessive space. This water is filtered through your pipes and fed into your household taps whilst also being used to heat up your radiators. By turning on the hot water tap, you trigger a response that signals the boiler to start heating water from the inside of the system. The heat exchanger transfers the majority of the heat from the burnt gas inside of the boiler to the cold water, and then delivers it to the taps as required.

Modern combination boilers are manufactured to double as condensing boilers which means that they are able to generate water vapour condensation to extract additional heat from its fuel. This is designed to make them even more energy-efficient as they produce more heat with less energy, potentially enabling you to reduce your monthly bills.

The control valves in combination boilers operate in different directions, so it either allows water to flow through the central heating system or diverts it to the appropriate hot water tap— but never both at the same time. You have the option of pre-setting your desired room temperature, this programmes the boiler to work with the room thermostat to ensure your home is heated as you like.


Get a free online quote  


Advantages of a new combi boiler

More and more homeowners are deciding to replace their conventional boiler with a combi boiler, which are typically more efficient. This isn’t surprising when you consider the multitude of advantages that could come with installing a new combi boiler into your home. Buying a combination boiler could positively impact your finances, the decor of your home and your overall lifestyle.

If you, like many others, decide to switch to a combi boiler you could benefit from a number of its advantages. For example, these boilers are designed to be:



There’s no need for any separate tanks or cylinders with combination boilers. They have everything they need packaged in one, so they could leave you with plenty of room to decorate your household as you please. Gas combi boilers could be a great choice for households with limited space.

Instantaneous Hot Water

By installing a combi boiler, you provide your household with on demand hot water. No water tank = no waiting time!

Efficient & Economical

Combination boilers are designed to be highly-efficient, producing condensation in order for more energy to be used rather than wasted. They also only heat the water that you use, enabling you to potentially make huge savings on your energy bill. You could save up to £215!**


The cold water released from a combi boiler is more likely to be safe for you and your family to drink as it is fed directly from the mains (although please note this is subject to environmental water advice in your area). This is not always the case with conventional boiler systems as they tend to store cold water in tanks.


As combi boilers release water directly from the mains, they are less likely to accumulate sludge or debris. This may help prevent boiler issues such as kettling from occurring and could thus save you money in future repair costs.

Potentially capable of boosting your home’s appeal

Due to the numerous advantages of having a combi boiler, you could add it to your list of selling points if you ever choose to sell your home.

Here at HomeServe, we aim to only install products supplied by the best boiler brands, helping ensure that your home heating is functioning in the best way at all times.

Here are some examples of popular brands that manufacture gas combi boilers:

Worcester Bosch Logo

A popular choice for homeowners within the UK, Worcester Bosch is a British-based domestic heating and hot water product manufacturer.

  • Rated Best Buy by Which? Online review
  • Premium quality
  • Environmentally Conscious

Find out more about Worcester Bosch boilers here.

Vokera Logo

Based in the city of Hull, this boiler brand has specialised in heating solutions for over 100 years.

  • Good Housekeeping Reader Recommended
  • 4-star Which? Online review customer rating
  • Promote strong Values of Customer Service & Innovation

Find out more about Ideal boilers here.

Vokera Logo

This brand is one of the UK’s leading heating manufacturers. Part of the Riello Group, Vokèra has been supplying quality heating products for over 30 years.

  • Continuous Innovation & Technological Advancement
  • H & V News Award Nominated for Domestic Heating Product of the Year
  • Extremely Versatile Products

Find out more about Vokera boilers here.

Vaillant Logo

Established in 1874, this brand pioneered the combi boiler over 35 years ago and has continued to create premium heating products ever since.

  • Extensive Industry Experience
  • Environmentally Aware
  • Forward Thinking

Find out more about Vaillant boilers here.

Baxi Logo

Based in the West Midlands, this brand has been active since 1866. Part of BDR Therma, Baxi aims to supply their customers with reliable, highly-efficient heating products.

  • Company ethos of pride, passion and positivity
  • Values of reliability, respect & innovation
  • Winner of heating product of the year with the Baxi 400 combi boiler

Find out more about Baxi boilers here.

Most popular gas combi boilers

Selecting a boiler for your household can be a difficult decision to make. If, like many homeowners, you’re struggling to make a choice, here’s an insight into our 4 top selling gas combi boilers of 2018:

1. Worcester Bosch 4000 25kW

  • Combination boiler, natural gas
  • Suitable for small to medium households
  • Sleek modern design - with digital display
  • Instantaneous hot water

2. Worcester Bosch 4000 30kW

  • Combination boiler, natural gas
  • Suitable for small to medium households
  • Modern design with easy to use digital, colour display
  • Operates well in low water pressure areas
  • 'Quick tap' water saving function helps reduce water waste

3. Ideal Logic 24kW

  • Combination boiler, natural gas
  • Designed with a backlit display & user-friendly controls
  • Designed with an easy to use pressure gauge
  • A suitable choice for most smaller properties with one bathroom
  • 395mm x 700mm x 278mm (Width x Height x Depth)

4. Ideal Logic 30kW

  • Combination Boiler, natural gas
  • Compact design
  • Designed with easy to use controls
  • 395mm x 700mm x 278mm (Width x Height x Depth)
  • An ideal choice for most households with limited space and no more than one bathroom


Get a free online quote  


Cost of a combi boiler installation

“How much will a new combi boiler installation cost?” This is a question on the minds of a great deal of homeowners in the UK. New combi boiler prices are dependent on a number of factors. These can include the type of boiler it is, its size as well as the cost and complexity of the installation process.

Often the cost of the combi boiler itself will be significantly lower than the overall price given by the person installing it. This will usually be due to the additional cost of installation, which can indeed be a complex process. Although this overall cost may seem expensive, it is important to remember that you are paying for quality. All installations should be carried out by a Gas Safe registered engineer who will follow strict protocol checks and procedures. This should provide you with peace of mind and allow you to have confidence in the fact that your installation has been completed to the highest regulated standard.

At HomeServe, we seek to offer customers access to flexible ways to pay for their new boiler installation. If you’d like to find out about the finance options that could be available, visit our access to finance page***.

Boiler prices can also be affected by the product’s brand. Here at HomeServe, we aim to only install boilers of high quality from reputable boiler labels. This allows our customers to rest assured that getting their home heating up and running effectively is our priority.

Here at HomeServe, we provide our customers with a means of assessing how much it would cost to install a new boiler into their home. Our free quote service will take into account factors such as your current central heating system, how many radiators you have and whether you are planning on having a gas combi boiler or an oil or LPG combi boiler. If you’d like to receive a valuable estimate of how much your new combi boiler installation could cost, try our instant, online quote now which will also highlight any of our available combi boiler deals.


Which combi boiler is best for my home?

Gas combi boilers can come in a range of shapes and sizes, each suitable for specific kinds of properties and rooms. Due to this, choosing the right boiler for your home can seem to be a quite a task. Nevertheless, ensuring that you make the right decision for your home is significantly important as it can affect the quality of heating that you and your family receive, and thus impact the level of comfort that you feel in your home.


A key factor to consider when making a decision about a suitable boiler for your home is the kW output required. kW outputs relate to the size of the boiler and are reliant on the number of bathrooms and radiators present within your household. The higher the kW output of your boiler, the better the supply of hot water you’d receive. However, this is not to say that you should purchase the highest output available, you must ensure that the boiler size correlates with the size of your home.

Here’s a simplified guide to the average kW output needed based upon the property size:

24-27kW 1-2 bedroom, 10 radiators, 1 bathroom
28-34kW 3-4 bedroom, 15 radiators, 1-2 bathroom
35-42kW 4+ bedroom, 20 radiators, 2+ bathroom


(This information has been supplied By Help-Link UK limited and has been produced for information purposes only and should not be used or relied upon as a substitute for professional advice by a suitably qualified engineer.)


Get a free online quote  


Benefits of switching to a combi boiler

If you make the choice of switching to a modern combi boiler, you could notice the advantages instantly. For example, you could have considerably more room available in your home as combi boilers, in contrast with conventional boilers, do not take up excessive space. A large amount of room is needed for conventional boilers as they require additional components such as cylinders and tanks. Additionally, with conventional boilers you can be limited to the hot water available in the tank; whereas with a combi boiler, hot water is always available at your command. Combi boiler prices can typically be kept cheap and easy because they usually hang on your wall in a single unit with less components required than a conventional or system boiler. Although, switching from one system type to another could incur some additional costs due to tasks such as pipework rerouting, as well as other factors.

All in all, getting a combi boiler installation into your home could prove to be significantly beneficial for your household. These boilers are typically extremely practical and efficient, using energy in the most useful way to deliver instantaneous hot water without using excessive fuel. Combi boilers can therefore be deemed as a cost-effective option, capable of saving you up to £215** on your yearly expenses. If you feel that you could benefit from installing a new combi boiler into your home, try our free quote tool online to get a better idea about how much a new installation could cost. We can then arrange an appointment with one of our trained surveyors, and you’ll be on your way to benefiting from the plethora of advantages in no time & not to mention you can utilise some of our great combi boiler deals!


*Subject to application, financial circumstances and borrowing history. Terms & Conditions apply. Other options are available. Finance can be taken out with or without deposit and capital payments can be made at any time to reduce your loan.

** Source: Saving calculated when replacing G rated with A rated boiler in a semi-detached house.

About the lender

HomeServe Membership Limited is a credit broker, not a lender. Barclays Partner Finance acts as the lender. If you choose a credit option, Help-Link UK Limited trading as HomeServe will receive commission from Barclays Partner finance which is a fixed percentage of the total loan amount. For more information, contact Help-Link UK Limited.

Barclays Partner Finance is a trading name of Clydesdale Financial Services Limited, a member of the Barclays group. Clydesdale Financial Services Limited is authorised and regulated by the Financial Conduct Authority. Financial Services Register number 311753. Registered in England under company number 2901725. Registered office: 1 Churchill Place, London, E14 5HP.