Combination Boilers

Learn more about the different types of boilers that are available to you.

What is a Combination (or) Combi Boiler?

Combination boilers, as the name suggests, combine most of the components of a conventional system (boiler, cylinder, tanks, pump & control valves) in one unit (The Combi). When first introduced to the UK in the early 1980’s, these types of boiler where only really suited for smaller homes.

Technological advances in recent years have increased the potential flow rate of hot water from these types of boilers dramatically, and they are now common place in homes with up to 5 bedrooms and 2-3 bathrooms. 

However, your installer should consult with you to determine your individual requirements before recommending this type of boiler, their recommendations should be based on simple principles such as how many people live at the property, how strong is the flow rate of the mains water coming into your home from the street (normally measured at the kitchen sink cold tap), and how likely is it that two or three hot water outlets may be required to be used simultaneously. Whilst combination boilers will heat almost every home in exactly the same way as any other boiler, the flow rate may vary depending on the answers to the above questions.


  • No stored water in loft or airing cupboard, therefore saving space and no risk of freezing pipes. 
  • Instantaneous hot water 24 hours a day, 7 days a week. 
  • High pressure showers without the need for mechanical power showers. 
  • The most economical type of boiler, only pay for exactly the hot water you use.
  • Because of the enormous flueing options Combis can be sited almost anywhere in the house, i.e. loft, airing cupboard, garage etc.
  • It eliminates the need for cold water storage tanks in the loft area (a good option if you are considering converting your loft space into living space). 


  • The only potential disadvantage of a combination boiler is that if several hot water outlets are likely to be required simultaneously, then a combination boiler will in most cases have a variation on hot water flow rate from the various outlets. However, given that the flow rates of combination boilers today are anything up to 18 litres per minute (LPM), they will serve most family homes with no problems whatsoever provided your installer has ascertained the requirements of your individual home and family needs.

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