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.
Answer: There are different types of composite boilers. Normally one part of the boiler is heated by means of a fuel oil burner and the other part is heated by the exhaust gases from a diesel engine. 1  Heating of one part of a boiler at the time often causes thermal stress that may lead to leakage.