Have a CSI 85..CH is working fine but hot water is non existent. Started out intermittent.. Boiler fires up and then switches off when hot tap is open and running..Have had an engineer out who replaced the gas valve and diagphram in the diverter valve with no luck..any ideas??
Many thanks

Ranko, March 2010

Does the 3 way valve actually move? It should move across and activate a microswitch at the end of the valve. If the answer is no, then the most likely cause is the whole of the valve is siezed and should be replaced. If the valve does move and activte the microswitch, then you should look to clean or replace the DHW Heat Exchanger. Replacing is usually best as cleaning may not remove all the scale build up succesfully. Hope this helps.

hawkeye2000, April 2010