While reviewing the energy usage both at work and at home I did some research on the subject of hot water and central heating. I found that although our boiler at home was only 12 years old it was rated as a G on the modern scale, where A is the most efficient 95-98% and G the least efficient 20-30%.

This prompted me to look deeper into the subject. A normal boiler where the oil, or gas in our case, heats the water and transfers it to a storage tank is the most inefficient method of all; the losses are great even with a fully lagged cylinder. A combi boiler is one where the water is heated on demand and is 60% more efficient than the indirect method. A combi condensing boiler is one where water is heated on demand and the hot exhaust gas normally vented to the air is used to heat a secondary coil; this extracted heat is then used to heat water. In addition exhaust gas emission is drastically reduced.

I decided on this combi condensing boiler as the one of choice. It is A-rated and heats the water as and when I need it. In addition it has a preheat facility that is turned off in summer that keeps a small reservoir of water hot so that there is no delay in obtaining hot water. The system also provided central heating.

I am assured that my gas bill will be drastically reduced as the change to a combi boiler will save 60% and then the condensing boiler will save a further 80% of the remainder.

At this rate my gas supplier should be paying me! but I believe I am in for a pleasant surprise when my next bill is due and I have the satisfaction that my CO2, CO and NOx emissions are much reduced.

About the Author

Chris Eden FIBA, MISSA, AIQA is a director of Quality Matters Limited, an established consultancy specialising in Quality (ISO9001), Environment (ISO14001), Information Security (ISO27001) and IT Service Management (ISO20000).