Guide to getting a new gas boiler installation

Gas boilers burn fuel to heat the water inside your home. These heating systems can either be powered by natural gas, which is piped into your home using an underground network, or by liquefied petroleum gas (LPG) which is supplied in bottles/cylinders. Gas boilers are available in a variety of forms such as system boilers and combi boilers.

Selecting the right boiler for your household is notably important as it can significantly impact the level of comfort experienced within your home. Additionally, the fact that boilers account for approximately 60% of the total cost of your annual heating bill** emphasises the necessity of making an appropriate choice. An energy efficient boiler could make a real difference to the average home.

Energy-efficiency is an important issue within current society. In 2005, a legislation stating that all newly fitted gas boilers are to be condensing was passed, making it mandatory for all new boilers to reduce energy loss by generating water vapour condensation and extracting additional heat from the fuel.

Here at HomeServe, we aim to only install top of the range boiler systems that heat homes in the most effective and energy-efficient manner. Try our free online quote tool to get an idea of how much it could cost to install a new, energy-efficient gas boiler in your home.


On this page we offer a comprehensive look at gas boilers, find out more about:



How does a gas boiler work?

Switching on your gas boiler is the first step in its functioning process. Once you have done this, a valve opens and allows gas from the mains to enter a sealed combustion chamber, this passes into a primary heat exchanger which is attached to a cold-water pipe. The hot gas then transfers its energy onto the water, heating it up and circulating it around the pipes and radiators within your home. This movement is powered by a pump.

The water that travels through the pipes gradually cools and is passed through a secondary exchanger, where it is reheated by the gases and produces a liquid called ‘condensate,’ which is then drained from the boiler.

At this point, as the gases have already transferred their heat energy onto the water, they have served their purpose and are no longer of use, so they are discarded out of the system via the flue. The remaining water that has already been heated and circulated around your radiator systems then flows back through the primary exchanger, where the process recommences so that the radiators can continue to heat your property. This cycle carries on until the thermostat detects that your home has reached the predefined temperature, or alternatively until the boiler is switched off manually.


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Types of Gas Boiler

There are three main types of gas boilers. This includes combi boilers, system boilers and conventional boilers. Each type of boiler has their own set of advantages and here at HomeServe, we are dedicated to providing our customers with state of the art heating systems that tend to the individual needs of each household.

Combi boilers

Combination boilers are one of the most popular choices of household boiler systems in the UK. Acting as a means of both heat and hot water, these heating systems are a great choice for anyone looking to save energy as well as space.

  • On demand heat and hot water
  • Compact (no cylinders or tanks required)
  • Designed to be cost-effective

Conventional boilers

Conventional boilers, also known as “regular boilers” provide heat to your homes through the use of separate hot water cylinders and cold-water tanks. These gas boilers are typically best suited for homes that already have a traditional heating and hot water system.

  • Hot water is available from multiple taps at the same time
  • Great for most homes that have two or more bathrooms
  • It could be cheaper to replace a conventional boiler if the individual components already exist

System boilers

System gas boilers provide heat without the need for a water tank as the key components are built into its one unit. A cylinder, however, is required in order to store the hot water.

  • Typically ideal for homes with limited space as no cold-water tank is required in your loft
  • Hot water is available from multiple taps at once
  • Designed to be economical to run


Advantages of a Gas Boiler

There is a plethora of advantages of installing a new gas boiler into your home. Gas is one of the cheapest fuel types available for domestic heating, so savings are amongst the many benefits that could be reaped by buying a gas boiler. Here are a few others:



Natural gas is one of the most energy-efficient fuels on offer. Less of this fuel is needed to heat water in comparison to other fuels such as oil or electricity. This, combined with the fact that most new gas boilers are condensing and thus maximise the heat extracted, constitutes to these boilers being an effective means of saving energy.


As gas tends to be relatively cheap in comparison to other fuels, gas boilers can be seen as a significantly cost-effective option. Additionally, whilst alternative fuels such as oil can be subject to market fluctuations, the value of natural gas tends to remain fairly stable throughout the year.


Purchasing a gas boiler tends to provide homeowners with added peace of mind. Whilst harsh weather can impair the quality of electricity-fuelled boilers, and oil-powered boiler systems can be hindered by oil shortages, gas boilers tend to be less susceptible to complications and can therefore be regarded as highly dependable.

Ease of Use

Gas boilers are often regarded as a convenient option for homeowners. There’s no need for a storage tank and you won’t have to check fuel levels; gas is supplied directly into your home from the gas grid.


Natural gas is the cleanest fossil fuel. It produces less carbon dioxide than other fuels like oil and coal and is significantly efficient when it combusts. LPG boilers are also known for being environmentally friendly.

Here at HomeServe, we work with some of the leading suppliers of gas boilers in the industry. Whether you’re in need of a system, combi or conventional boiler, we've got the knowledge and expertise to help you select the best brand and model for your home.

There are a number of brands within the heating industry that manufacture gas boilers. These include:

Worcester Bosch Logo



Worcester Bosch produce their boilers with exacting standards and only the best materials.

  • Compact dimensions
  • Removable side panels and push-fit flue system
  • COMFORT’ warm start feature for increased delivery speed of hot water
  • 720mm x 440mm x 335mm (height x width x depth)
  • An ideal choice for small to medium homes with average hot water demand


Baxi Logo

The Baxi brand specialises in producing high efficiency boilers that are easy to install, maintain and service.

  • 5-star energy efficiency rating on Which? Online review
  • Aims to provide high quality service & technical support
  • Claims to prioritise environmental, social & economic sustainability

Ideal Logo

Reader Recommended by Good Housekeeping Magazine, Ideal offers products for every home and every lifestyle.

  • Manufactured in Britain
  • Over 100 years’ industry experience
  • 4-star Which? Online review customer score


Vaillant Logo

Vaillant created the world’s first gas fired water heating system and have acquired a number of awards with their current range of ecoTEC boilers.

  • A unique combination of German design & UK manufacturing
  • Products available in a range of options and styles
  • 5-star rated build quality on Which? Online review


Vokera Logo

Providing customers with easy and reliable products, Vokera delivers a comprehensive range of products for domestic home heating.

  • Designed for easy installation & operation
  • 5-star rated energy efficient products on Which? Online review
  • Over 1.5 million boilers installed across the UK & Ireland


Glow-worm Logo

Glow-worm has been manufacturing reliable heating products for over 80 years and their experience and work ethic has led them to become a trusted heating brand.

  • Highly efficient heating products
  • Products are designed to be easily installed and repaired
  • Affordable range of products


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Many homeowners have improved the quality of their household heating by buying a gas boiler. To help you get past the first step of deciding which boiler system could benefit your home, here’s a list of our top 4 selling gas boilers:

Worcester Bosch Greenstar 30i

  • Combination boiler, natural gas
  • Suitable for most small to medium homes with one bathroom
  • 400mm x 710mm x 330mm (Width x Height x Depth)
  • On-board operational information and diagnostics
  • Contains condensate syphon to eliminate the risk of condensate pipe freezing

Worcester Bosch Greenstar 25i

  • Combination boiler, natural gas
  • Ideal for most small to medium sized homes with one bathroom
  • 400mm x 710mm x 330mm (Width x Height x Depth)
  • On-board operational information and diagnostics
  • Contains condensate syphon to eliminate the risk of condensate pipe freezing

Worcester Bosch Greenstar 15RI

  • Conventional Boiler, LPG Fuel
  • Suitable for most small properties with lower heating and hot water requirements
  • 390mm x 600mm x 270mm (Width x Height x Depth)
  • A rated efficiency 90% (SAP 2005 seasonal efficiency)
  • Compact built- suitable for kitchen cupboard storage

Worcester Bosch Greenstar 18 Regular RI

  • Conventional boiler, LPG Fuel
  • Ideal for most flats and bungalows
  • 390mm x 600mm x 270mm (Width x Height x Depth)
  • A rated efficiency 90% (SAP 2005 seasonal efficiency)
  • Built-in heating temperature control


The Cost of a New Gas Boiler Installation

Some of the main questions on the minds of homeowners facing boiler dilemmas are: “How much is a new gas boiler?” “Are there any cheap gas boilers for sale?” Here at HomeServe, we’re more than happy to help answer your questions.

The price of a new gas boiler can vary, with prices being dependant on factors such as the brand of the gas boiler selected, its size and the requirements of the installation.

The cost of the boiler itself will usually be significantly lower than the overall price given by the engineer. This is often due to the additional cost of installation, which can indeed be a complex process. Although this overall price may seem expensive, it is important to keep in mind that you are paying for the quality of your household heating. Additionally, by ensuring that the job is completed to a high standard by a registered Gas Safe engineer, you will be safeguarded against any regulatory issues.

At HomeServe, we understand that you may not be able to pay for your new boiler outright. That’s why we aim to offer flexible ways to pay with a range of finance options available, find out more on our access to finance page***.

Our free quote tool will provide you with an estimated cost of a new gas boiler installation. The quotation process will consider factors such as your current central heating system and how many radiators you have in your home. Receive your fixed price quote**** online in 3 simple steps.


Which Gas Boiler Do I Need in My Home?

Making a decision about which gas boiler is best suited for your household can be a puzzling process. We’re here to help make this as easy and stress free for you as possible, providing you with a gas boiler that will meet you and your family’s needs.

Gas boilers are available in a variety of sizes, shapes and brands. However, the main factor that you must consider is the kW output required for your household. The kW output will dictate the size of boiler that is required in order for your home to be heated effectively and is dependent on the number of bathrooms and radiators that you have within the property. Generally, the larger the property, the higher the kW output your boiler needs to be to cope with the higher demand for heat and hot water.

Here's a simplified guide detailing the average kW output needed for different property sizes:

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.)

There are a number of factors to consider when purchasing a new gas boiler. It is important that you make a careful, well-informed choice in order to get the most out of your investment. We’re here to aid you in making your decision and will aim to ensure that your new gas boiler is installed with care and precision. So, whether you’re in need of a new combi, conventional or system boiler, we’re committed to providing you with a first-rate service.


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*5% online discount is available to domestic gas and LPG customers who receive an online quote for all boiler brands excluding the Ideal Logic HE24, HE30, HO15 & HO18 and Worcester Bosch 25i ERP, 30i ERP, 15ri & 18ri boilers which qualify for the winter bundles offer. £50 additional discount available on all like-for-like system swaps and a £100 additional discount is available on conventional to combi, and combi to conventional boiler swaps. Online discounted price is only available for the duration of the 14-day quote validity which starts from the day the quote was given. Help-Link UK Ltd include a filter as part of your quote as this is highly recommended by the boiler manufacturer as a key component in maintaining boiler health, functionality and may potentially be looked upon favourably by manufacturers when assessing warranty work. This filter can be removed at the customer's request. Quote also includes a programmable thermostat for all combi boiler installations as this is a legal requirement as part of the Boiler + legislation introduced 6th April 2018, and cannot be removed from the installation unless; it is replaced with an alternative smart thermostat; or another energy saving measure as listed in the Boiler + legislation or if a smart thermostat already exists within the property. Alternative thermostats, including smart thermostats are subject to an additional charge.


***24 months Interest Free Credit is only available on Worcester Bosch boilers. Credit is subject to status, affordability assessment and credit checks. Terms & Conditions apply.

****Exclusions apply. See