About System Boilers

system boiler diagram

System boilers are very economical and heat your home efficiently. Many people cannot tell the difference between a regular boiler and system boiler. So what is the difference? A system boiler takes up less space than a regular boiler because it encompasses the cistern tank and other components but also still provides a solid flow of hot water. HDM recommend a system boiler for slightly larger premises that have more than one bathroom or want a dry (no water tanks) loft area.

The system boiler already has lots of major components of a heating system built in so this makes for a quicker and easier installation. Also the hot water from the system boiler is pumped through the radiators and hot water cylinder, which in turn delivers a faster response and is more economical which means less on running costs. As all the major components are built in it saves space and combines many of the advantages of a regular boiler with a combination boiler.

Pros and Cons of System Boilers


  • All major components are built in which means less space is taken up.
  • System boilers are easier to fit and install and are very economical.
  • Provides a faster response for hot water as and when it is needed.


  • Unless the cylinder is well insulated it will lose heat.(This is also true for the feed expansion tank in the loft on regular boilers.)
  • If the cylinder is not well insulated you will have to wait for it to heat back up again to run a hot bath.
  • The amount of hot water that can be supplied is dependent up on the size of the tank.


HDM recommend the a system boiler for larger premises that require a lot of hot water for all different facilities. But also don't have the space for a regular boiler that needs a feed expansion tank in the loft. If you decide the system boiler isn't for you or you wish to obtain more knowledge of different types of boilers then you can find our more below...

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

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