What are combination condensing boilers and how do they work?

Well there are many myths and misconceptions about condensing system boilers.

Are combination condensing boilers the same as regular boilers?

No. Condensing system boilers are not regular boilers.

They are like a condensing combination boiler but without the hot water side.

Are they condensing combination boilers?

No. Condensing system boilers are not combination condensing boilers as they do not have a hot water heat exchanger that can provide instant hot water.

Are condensing system boilers floor standing?

Not really..

Most leading brand makers of condensing system boilers are wall mounted – which means that the boiler is fixed to the wall.

However, some companies have condensing system boilers that are floor standing. You can also convert a floor standing combination condensing boiler to be used as a floor standing condensing system boiler.

So what are condensing system boilers?

Well, condensing system boilers are simply a pressurized, condensing regular boiler. So a condensing regular boiler with an expansion vessel in and a pressure relief valve to pass the 3g water requirements.

Condensing system boilers negate the need to have a feed and expansion tank in the loft, as the heating system is filled indirect from the mains water. This means you have what is called a closed or sealed heating system which is not opened to the atmosphere rather than an open vented system which is opened to the atmosphere and is filled by gravity through the feed and expansion tank which is normally in the loft.

The benefits of a condensing system boiler are –

  • No tanks in the loft or cupboard areas.
  • Easy filling of the system through the mains water.
  • Less likely to get an air-lock through filling and flushing, due to mains pressure.
  • Sealed systems are generally much more energy efficient as the whole system is under mains pressure so it circulates more quickly.
  • Less likely to collect sludge in a sealed system as sludge requires hot water to be mixed with open air to form sludge.


Please call or mail us for more information on how we can improve your heating system by installing a new condensing system boiler.

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