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.
How Do Ventless Gas Heaters Work? Because all combustion heaters require oxygen for their burning process, traditional heaters draw on the unlimited supply of outside air to sustain combustion. In addition, there are many types of combustion heaters such as pellet stoves and wood-burning stoves that do not completely burn away the fuel source.