Something else to consider is the effectiveness of your new combi boiler all boilers are appraised on a productivity scale running from a to g those with an evaluation of a are the most energy proficient it has been recently announced by the european union that boilers not graded an a will no longer pass standards when you buy your unit with us, you have an excellent selection of energy efficient combi boilers with an a rating, that can be perfect for any home. The results of our price.