What is a condensing boiler?
- James Hoskins
- Jul 22, 2019
- 1 min read
What is a condensing boiler? In the UK in 2015 it was made compulsory that all new domestic boilers be of the condensing type.
Are combi boilers and a condensing boilers the same thing? No they are not. A condensing boiler is not necessarily a combination boiler; but all combi boilers are now condensing boilers!
A standard efficiency (band D) boiler would expel a large amount of the heat it produced with the products of combustion. In other words, the gas would ignite and heat would be produced, and this heat would go straight out of the flue into the air outside! What a waste of energy and money!
Condensing boilers were the result of designs being made to prevent such a large proportion of the heat produced by the boiler escaping outside.
In a condensing boiler, the water in the flow pipe from the boiler is still heated by the flame as it leaves the appliance. The difference lies in where the flue gasses and the water in the return pipe are routed. As the water returns to the boiler it is heated by the hot flue gasses and much of the heat that would have otherwise be lost, is utilised efficiently inside the boiler.
It is worth noting that your gas boiler will only condense correctly if the boiler and system are set up properly.
In order to maintain the safety and efficiency that you have your boiler serviced regularly by a Gas Safe engineer. Give Hoskins Heating a call on 01384 293426 or 07792 066071 today.


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