About Combi Boilers

system boiler diagram

Combi boilers are far more efficient than older boilers because they use more gas due to their design and the deficiencies after long time usage. Older boilers over 10 years old are almost certain to have less efficiency than the new combi boilers available today. HDM offer only 'A' rated energy efficient combi boilers which equates to around 90% or more in fuel efficiency, that means a lesser impact on your wallet.

Combi boilers heat water on demand and so there is no wasted fuel heating a big hot water cylinder only for it to cool down again or sit there unused. Also since they are classifies as high efficiency or 'condensing boilers, they utilise more of the heat generated than older boilers used to, and tehrefor save money by reducing your gas bill.

Pros and Cons of Combi Boilers


  • You don’t need a water tank fitted and all water gets heated as and when it’s needed.
  • They heat the home very efficiently and have fewer carbon emissions.
  • You can fit the boiler in tight spaces.


  • They are not suitable for large homes because lots of appliances can be used and there will be a significant loss in pressure.
  • Combi boilers rely on water pressure.
  • The more facilities used the lower the flow of the water will be.

Overall HDM don’t recommend a combi boiler for large homes with lots of facilities. However for smaller homes combi boilers are very good and could save you a lot of money. HDM can fit all types of boilers for example combi boilers, heat only or a system boiler we are here to help. If you are unsure that a combination boiler is right for you take a look at all our other boiler types and how they match with you.

There are three types of combi boilers...

If you believe a combi boiler will suit your needs then take a look even further and see which type of combi boiler you require...

Not sure or a combi boiler is not for you?

If you decide on the knowledge given that a combi boiler is not for you or you wish to find out more about different boiler types then take a look at our other boiler types...

or call Kim on 0800 7797045 or our mobile friendly number 01937 345100

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