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Combi boilers - How They Work

  • Posted by:
  • Admin
  • Tags:
  • Combi Boiler
  • Posted date:
  • 29-07-2019
Combi boilers - How They Work

A combi boiler is used to directly control the entire central heating system from one compact unit. Combi boilers have become commonly used in the UK with people upgrading from using traditional and conventional boilers.

Advantages of combi boilers

The combi boilers are straightforward and faster to install since they do not require any pipework. The combi boilers give unlimited and instant access to hot water. With combi boilers, there is no waiting around for the hot water cylinder to warm up.

Combi boilers can condense heat; meaning that the boilers use most of the energy they produce, and only some of the power is wasted. They do so by generating heat from flue gasses that would otherwise be wasted away if the boilers were non-condensing. The combi boilers require minimal pipework, thus making installation of the boilers easier, faster and also cheaper.

How do combi boilers work?

This type of boiler works by having the compact heating system heat both the radiators and the hot water. Having this system eliminates the need for an additional external hot water cylinder or cold water tank. The combi boiler can provide instant hot water. Immediately you turn the hot water tap on; which creates a signal to tells the boiler to start heating the water.

The water is heated faster as the heat exchanger transfers the heat produced from the burned flue gasses to the cold water. The cold water tank then delivers the water to the tap as required. The control valves found inside combi boilers function in different directions. The control valves can either allow the water to flow via the central heating system or help in diverting the water towards the appropriate hot water tap. However, the control valves do not carry out these two functions at the same time.

You can also set the temperature you desire your house to be heated to by pre-setting the desired temperature. The boiler then works with the thermostat to ensure the house in preheated at the desired temperature. When it comes to combi boilers, the tap water and the water at the central heating system does not mix. The domestic hot water system and the central heating system are in separate pipes, because of this the water never mixes.

We recommend ensuring you consider the cleanliness of the radiator and pipework before a new boiler is installed in your home, as this can cause damage to the boiler.


If you are thinking about installing a new combi boiler, get in touch with our boiler engineer to discuss your central heating needs.