Condensing boilers, in a nutshell, are far more efficient than standard boilers. Typically, they convert 90 per cent and upwards of energy into heat (compared to an old boiler whose efficiency can be as little as 60 per cent). Condensing boilers should not be confused with combination (or ‘combi’) boilers. Combi boilers provide hot water heated on demand directly from the boiler, rather than through a separate hot water storage cylinder. Condensing boilers condense the vapour back into water,