Can i just say don t waste money on buying the whole assembly of the diverter valve, all that should be needed is a diaphragm repair kit for this model, pritty much all heating merchants should be able to supply u with instead of paying 50 for the valve, why not try 15 for the kit? plus u dont need to drain the boiler down if u get the kit all u need to do is turn the cold water inlet to the boiler off and hey presto sorted ;)
Fraser Gomersall, July 2009