This part is based around the diverter valve section. The diverter valve is an instrument that only appears in combi boilers. It allows the hot water to be redirected to the central heating system (radiators, etc.) or to the hot water system (taps, etc.). This feature is what makes a combi boiler so popular due to the boiler being able to provide heating and hot water without requiring a cylinder.
We recommend that all parts are fitted by a fully qualified gas safe certified plumber.