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 Hydronics Works | HVAC Technical for Consumers - Hydronics and Boiler Systems. The process of hydronics can also be used with boiler systems. Hot water boilers or steam boilers can be used to heat water and deliver the water to heat exchangers inside the building for both comfort heating and process heating.