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How does a combi boiler work?


Your home’s boiler is one of its more important aspects. There are heat only boilers, system boilers, and a third kind of boiler, commonly referred to as a combi boiler.


What is a combi boiler?

More formally known as a combination boiler, a combi boiler serves as both a central heating boiler as well as a water heater. They’ve become increasingly popular over the years thanks to the space they’re able to save by having both of these essential home services in one compact unit. 

The benefits of a combi boiler

  • They provide instant on demand hot water
  • They’re compact and therefore don’t take up much space
  • They’re efficient and therefore economical
  • Can boost the value of a home

You might be wondering how they work, so let’s take a look at the intricacies of a combination boiler to see how they help your home.


How does a combination boiler work?

Boiled down to its most basic explanation, a combi boiler works how you might expect. Say you turn on a hot water tap in your home, this ignites the combi boiler’s gas burner and then a heat exchanger transfers this energy to heat up the water that is taken from the mains. This happens almost instantly, providing hot water very quickly.

A more in-depth look at a combi boiler shows that the burners within the boiler are activated when the valves are turned in central heating and hot water systems within a property. An open tap allows water to flow where it’s needed. When the flowing water passes over a paddle switch within the boiler, it will turn the burners on in the part of the boiler that heats water for the taps. The heat exchanger that was mentioned earlier is a small compartment that stores surplus heat.


An example of the heat exchanger in action would be extra heat from the central heating being used to heat the water for the taps. Because the central heating pipes and domestic hot water pipes both run through the heat exchanger, they can always heat each other and be hot at the same time, which is the core reason for owning a combi boiler.


Combi boiler prices

The price of installing a combi boiler can vary, but on average you should expect to pay between £500 and £2000, depending on your property and other factors. For more information, view our full combi boiler price guide!


If you are looking for quotes from local combi boiler installers, just enter your details into our simple form and let us do the work. Trusted boiler companies will be in touch to talk you through options & quotes.



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