The CE mark, or formerly EC mark, is a mandatory conformity marking for certain products sold within the European Economic Area (EEA) since 1985. The CE marking is also found on products sold outside the EEA that are manufactured in, or designed to be sold in, the EEA.
Condensing boilers are water heaters fueled by gas or oil. They achieve high efficiency (typically greater than 90% on the higher heating value) by condensing water vapour in the exhaust gases and so recovering its latent heat of vaporisation, which would otherwise have been wasted.
Unlike a combi gas boiler system, an open-vented heat-only gas boiler system (with a water tank) has components housed externally from the boiler, such as a circulation pump. This type of system will also usually require cold water, as well as feed and expansion tanks in the loft.With a heat-only boiler (also known as a conventional boiler system), the hot water is stored in a hot water cylinder or hot water storage tank.his type of system will also usually require cold water, as well as feed and expansion tanks in the loft. With a heat-only boiler (also known as a conventional boiler system), the hot water is stored in a hot water cylinder or hot water storage tank.