What is a Condensing Boiler?

Differences between new and old condensing boilers:


  • Old condensing boilers use a different amount of useable heat they produce from the fuel it burns in comparison to new condensing boilers
  • Old condensing boilers usually have a pilot light, which is burning all the time, despite whether the boiler is switched on or not
  • A condensing boiler is more efficient than a non-condensing boiler, it has a much larger heat exchanger, which extracts over 90% of the heat from the fuel it burns, making it much more cost effective to run
  • It extracts the heat from the flue gases, which would otherwise be lost to the atmosphere, and recycles the heat back into the heating system
  • The water vapour in the flue gases can be so cool that it condenses (hence the name!), and is taken away to a waste pipe through a condensate pipe
  • New condensing boilers do not need a pilot light burning all the time, because they fire up when there is a demand for heat, suing an electric spark.

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