This Vaillant condensate hose is suitable for use with the ecoTEC VU (condensing), ecoTEC VUW (condensing) and ecoTEC VUI (condensing) boilers. A Condensate Trap extracts the condensate discharge which builds up in the heating or cooling system. Condensate is created by changes in the temperature and pressure within those systems. A discharge pipe joined to the condensate trap then allows any held water (Condensate) to pass through & out of the property. The water contained within the condensate trap can contain mild levels of acid, for this reason discharge pipes are made of plastic.