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Combi Boilers

//Combi Boilers

What is A Combi Boiler?

A combination boiler, most commonly known as a combi boiler, is the most popular type of boiler system in the UK and is usually preferred in new boiler installations. Combi boilers provide you with both hot water and heat for radiators, functioning as one compact unit and does not require a hot water cylinder.

There are many different types of combi boilers available and the most efficient boiler for you depends on the property size, family size or your needs. Choosing the correct type of combi boiler is very important as it will keep your house warm, energy efficient as well as maintaining reduced central heating bills.

As the price of a combi boiler installation is different to a system boiler installation; by choosing the best suited new A-rated combi boiler will help save you money. We can help you find the most suitable combi boiler for your home as well as help you find and compare the best boiler price with our free boiler quote service.

How Does Combi Boiler Work?

Combi boilers are connected to the mains water supply and are constantly on standby mode. When the central heating is switched on, water gets heated within the boiler and sent to the radiators. When the hot water tap is turned on, the combi boiler heats the water through a heat exchanger and hot water is instantly generated.

Condensing Combi Boiler

Most of the new boilers, such as combi, regular or system boilers are also called condensing boilers. The biggest difference between a condensing boiler and a non-condensing boiler is the flue gas recovery system. Condensing combi boilers contain a flue gas recovery system that captures the heat from waste flue gases and reuses it to heat the cold water inside the boiler, making them highly energy efficient. However, in a non-condensing boiler these gases will be unused and wasted. Condensing boilers also contain a condensing pipe that is connected to the drain, which discharges condensation safely.

Advantages of a Combi Boiler

Size of a Combi Boiler

Combi boilers are compact in size and consist of a small single unit. Combi boilers do not require a hot water tank, such as those used in traditional boilers, therefore meaning they require less space and thus could easily fit into a kitchen cupboard.

 Energy Efficiency and Lower Energy Bills

An A-rated Combi boiler is very energy efficient and by law all new combi boilers are required to have at-least an efficiency of 92%. This efficiency not only keeps your house warm but also results in lower energy bills.

Instant Hot Water

Combi boilers produce hot water instantly, within seconds of turning the tap, as it does not require a tank to fill up, giving you efficiency and low cost.


A Combi boiler is a compact and made up of only one unit, making it very easy to install. It is very easy to find a space to fit a combi boiler and installations require less time meaning lower costs. Combi boilers are most commonly used and therefore it is much easier to find qualified engineers in your area. They are also cheaper to service compared to system boilers.

Disadvantages of  Combi Boilers

Property Size

Property size is very important when choosing a new boiler. Combi boilers aren’t suitable for large properties or where a heavy supply of hot water or a central heating system is needed. When the hot water is turned on heating will be paused. Combi boilers are ideal for small to medium size properties.

Higher Mains Pressure and old Pipework

Combi boiler requires a higher mains pressure and are not suitable in properties where water pressure is an issue. This will result in slower water pressure to the boiler and to the taps. This, however, could be resolved by buying an extra pump to get a better flow. A trusted local engineer should be able guide you with this decision and help to identify if your existing pipe work is too old and needs replacement. (This will automatically increase the cost to your boiler replacement).

Types of Combi Boiler

Mostly combi boilers are known to be gas combi boiler, they are also available in LPG, Oil and electric.

Gas Combi Boiler

Most houses in the UK are connected to a natural gas source, hence gas combi boilers are the most commonly installed boiler in the UK. Combi boilers are very compact and require no additional space.

LPG Combi Boilers

LPG combi boilers require the same setup as an oil boiler meaning you need to store oil outside of your property and extra space is a necessity. An LPG boiler uses a combination of natural gas and oil; it is important to have a supplier available so you can top up when required.

Oil Combi Boilers

Oil combi boilers are a very popular boiler with homes that do not have natural gas.  An oil combi boiler requires a setup of a tank that stores oil, which is then kept outside your home. You need to have a supplier in place so you can fill it up when required. The oil combi boiler price will be higher due to the additional tank.

Electric Combi Boilers

Electric combi boilers are used when your home is not connected to a gas grid and there is no extra space to store oil. These combi boilers could be expensive and due to their low efficiency, these boilers are not recommended for larger properties.

What size of Combi Boiler do I Need?

There are a wide range of combi boilers available in the market. It depends on the size of your home and needs when choosing a combi boiler, e.g. if your demand for water is low and your house is relatively small then you can buy a low output combi boiler and if the demands are high then a higher output combi boiler. Choosing a wrong boiler could cost you more in the boiler installation cost and energy loses.

Your local recommended engineer should be able to help you in making your decision and you can use our service of a free no obligation boiler quote to choose the best combi boiler at best installation price. You can compare the cost of a combi boiler replacement and save money on a new combi boiler installation.

To give you an idea, we have prepared a general guideline with the help of local recommended engineers, in our network:

combi boiler prices fitted

Best Combi Boilers

There is wide range of combi boilers available in the market and below are some of the Best Combi Boilers. Combi boiler prices depends on various brands and output.

ManufacturerModelSize (KW)
Worcester Bosch boilerGreenstar i25,30 KW
Vaillant boilereco Tech Pro24,28,30 KW
Baxi boilerEco Blue+24,28,33 KW
Viessmann boilerVitodens 100-W30KW
Intergas boilerHre 28/2428KW

All these boilers have been rated highly by the users and recommended by local trusted engineers. A trusted gas safe engineer should be able to recommend you a best combi boiler suited for your home.

 Combi Boiler Prices

Combi boiler prices and boiler installation costs depend on various things. In general combi boiler prices range anywhere between £450 – £2000 and you should consider extra cost for boiler installation. Here’s a guide for the best combi boilers in 2018.

ManufacturerModelStandard warrantyAverage Price
Worcester Bosch boilerGreenstar i5 years£900 – £1200
Vaillant boilereco Tech Pro7 years£950 – £1300
Baxi boilerEco Blue+7 years£850 – £1250
Viessmann boilerVitodens 100-W5 years£850 – £1000
Intergas boilerHre 28/247 years£850 – £1200

The above prices are only a guideline only, which do not include the cost of installation. At Compare heating Quotes you can get quotes for combi boiler installations, supply and fitted, from local recommended engineers.

Combi Boiler Installation Cost

A new combi boiler installation cost is between £500 – £800 for a straight forward or like for like boiler replacement. If you are changing a type of boiler or location of your boiler, the installation cost of the boiler will most likely be between £1500 – £1900, depending on the extra work required.

The cost of a combi boiler installation will vary from provider to provider and Compare Heating Quotes will help you get multiple quotes from your local trusted engineers so you can save money and stay in control of the whole process. Remember, all boiler quotes or central heating system quotes are provided free of charge and you are not obliged to go ahead with the order.