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.
The boiler generates high pressure steam by transfering the heat of Combustion in various heat transfer sections. This part of the article series briefly describes the flow and arrangement of the heat transfer sections in a boiler. In line diagrams help make the concept clear.