What Is a Condensing Boiler?
A condensing boiler is a high-efficiency boiler that recaptures heat from flue gases that would otherwise be wasted. It is important to understand that "condensing" describes the boiler's technology, not its type — you can have a condensing combi boiler, a condensing system boiler, or a condensing heat-only boiler. Since April 2005, all new gas boilers installed in England and Wales must be condensing boilers by law. All new combi, system, and heat-only gas boilers sold today are condensing units.
Why Are Condensing Boilers More Efficient?
In a traditional non-condensing boiler, hot exhaust gases escape up the flue at temperatures of around 180–220°C. This represents a significant loss of energy that has already been paid for. A condensing boiler adds a secondary heat exchanger that extracts much of this waste heat before the gases leave the flue. The recovered energy pre-heats the cooler water returning from the radiator circuit, reducing the amount of gas needed to raise the water to the required temperature.
As the flue gases are cooled to around 50–60°C, the water vapour they contain condenses into liquid — hence the name. This condensate (a mildly acidic liquid) must be safely drained away, typically into a household waste pipe.
How Much Can You Save?
The savings from switching from an old non-condensing boiler to a new A-rated condensing boiler can be substantial. According to the Energy Saving Trust, replacing a G-rated non-condensing boiler with a modern A-rated condensing combi boiler can save a typical UK household between £200 and £500 per year on gas bills, depending on the property size and tariff.
New Condensing Boiler Installation in Corby and Northamptonshire
Every boiler we install at Corby Boiler Installations is a modern condensing unit meeting current UK building regulations and efficiency standards. Our Gas Safe engineers install boilers from Worcester Bosch, Viessmann, Vaillant, Baxi, and Ideal — all with A-rated efficiency ratings and manufacturer warranties of up to 12 years.