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What is a Combi Boiler & What Size Boiler Is Best For My House?

How can I choose the right combi boiler for me?


Choosing the right size combi boiler for your home can be bewildering. And whilst it is advisable to consult a Heating Engineer or Gas Safe Plumber to give you advice on your new boiler selection, it is useful to have an idea of what you will need for budgeting. We have given a rough guide below to help you plan and get the right size boiler for your heating system overall at home.

What size combi boiler is best for my house?

Combi boilers are available in three size ranges here at Mr Central Heating; 24 to 27kw28 to 34kw and 35 to 42kw.

  • As a rough estimate most flats, apartments and smaller houses, with up to 10, average size radiators and 1 bathroom* will require a 24 to 27kw Combi Boiler.

  • For a medium to large 3-4 bedroom house with up to 15 average size radiators, 1 bathroom and an ensuite* bathroom, a 28-34kw Combi Boiler would be installed.

  • 35kw and a 42kw Combi boiler would be for a large house with anything up to 20 average size radiators and 2 bathrooms*.

For properties where a higher demand of hot water is needed the higher the kw of the boiler, the better the flow rate of hot water will be. *However combi boilers do not cope well with 2 showers running at the same time in the same property, due to the use of hot water across both showers. Where this is a requirement a system boiler with an unvented cylinder should be considered. This is because combi boilers heat water directly from the mains when you turn on a tap. The good news though is that you will no longer need a hot water cylinder or a cold water tank in the loft space, roof or basement though.  It also helps with energy efficiency in the home.

 

What is a Combi boiler?

One of the main types of boilers is a combi boiler (or to give it it's full name a combination boiler) and this is the name cold water boiler given to a boiler that provides heat for central heating and heats water instantaneously on the opening of a hot tap. Other types of boilers include gas boilers, regular boilers (also known as conventional boilers or heat only boilers - which feature a storage tank) and system boilers. With a combi boiler, the water is fed from the mains so the water pressure is generally greater. This boiler type is one of the more high efficiency boiler systems available and at a price that fits most budgets when it comes to the right boiler cost, installation costs and overall energy bills moving forward.

It is ideal for smaller properties, and boiler brands available on our site include Baxi, Glow-worm, Ideal, Potterton, Vaillant, Worcester Bosch and more. Find out what boiler might work best for your central heating system and view all available combi boilers here. Note: This information is not going to be accurate for every property as room sizes can vary wildly from property to property, but will give you a good idea when consulting with a heating engineer over your needs.