What’s the Difference Between System and Heat Boiler?

If you are building a new home or looking to renovate your existing one, chances are, you might be looking to replace your old boiler.

In which case, choosing the right boiler for your home can be difficult. Keeping that in mind, here’s some information on the main differences between the system boiler and the heat boiler so that you can make a more informed decision when the time comes to decide on a boiler for your home.

System Boilers

System boilers are considered to be extremely cost effective and efficient when it comes to heating a home. A system boiler takes up less space as compared to a regular boiler since it encompasses the cistern tank along with other components of a boiler. A system boiler is the best choice for those people who own larger homes. Also, since a system boiler already has all of the components that are necessary for a heating system it is easier and quicker to install. The system boiler also has a quicker response since the hot water from this boiler is pumped through the radiators and the hot water cylinder whenever needed.

Pros and Cons of a System Boiler


  • All of the major components of the boiler have been built in, which means it takes lesser space as compared to the more conventional boilers
  • A system boiler has a quicker response rate when it comes to delivering hot water since the hot water is pre-heated and stored in the cylinder
  • As compared to others, the system boiler is much easier to install.


  • You will have to wait for the water to heat if the cylinder has not been well insulated.
  • A poorly insulated cylinder can also result in a loss of heat.
  • The amount of hot water which can be used via a system boiler depends on the size of the hot water storage tank.

Heat Boiler

Heat only boilers are able to efficiently heat a home. This type of boiler uses a storage cistern along with dual feeds, one for cold water and the other for hot water. The stored water is then heated up and stored again until it is used. The hot water feed is also pumped throughout your home to keep it warm. Heat only boilers are also know as regular boilers because they are the more conventional way of heating your home. Heat only boilers are the best choice for larger homes since they are able to supply hot water consistently.

Pros and Cons of Heat-Only Boiler


  • Provides hot water even if the pressure in the mains is low
  • The heat only boiler can provide hot water even when multiple showers are on without a drop in temperature
  • A heat-only boiler has a simple design and is easier to maintain


  • Often results to poor pressure flow for showers
  • Additional space required for feed tanks (one for hot water and one for cold water storage)
  • Possible heat loss in stored water when it is not in use.

Ending Note

These are the pros and cons of the two types of domestic boilers for your home. Hopefully, the information provided here will provide you with a better understanding the next time you are in the market to purchase either system or a heat boiler. You can find out more about the system or heat only boiler on our website or by talking with our boiler expert.

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