This Baxi valve cartridge is suitable for use in Duo-tec ErP, Promax ErP, Titanium ErP, Platinum ErP, Gold ErP and Platinum + appliances. A directional water device in combi Boilers, a diverter valve directs hot water into either a heating system or a hot water system. This feature means that combis are able to provide both heating and hot water Without the need for a storage cylinder.