Energy efficient and cost effective Thanks to the fact that they are over 90% efficient, condensing boilers offer great value for money over time and also have less of a negative impact on the environment that older boiler types. Whilst they can be a little more expensive to purchase, the fact that they are more efficient should outweigh this. Compact design If you opt for a condensing combi boiler there is no need for water storage tanks, making it ideal for a smaller property. The size of the boiler itself can also be much more compact and modern in design than many older models.