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 a Central Gas Heating System Works Simply put, a central gas heating system creates a cycle of increasing the temperature of cooler air. Here is the simple version: 1.Burning propane or natural gas generates heat in the furnace's burner. 2.The heat produced passes through a heat exchanger, making it hot. 3.Air from the home's ductwork is blown over the heat exchanger, warming the air.