The "diverter valve" has gone bang on my mum's central heating system and we are told that it is obsolete.
The system looks very much like a modern Y plan system - fully pumped, 3 port valve, separate timed control of heating and hot water, etc. The only difference from a modern Y plan system is that the wiring box contains a relay.
The plumber is being useless, so I may have to do the work myself, it should be a straightforward task to replace the "diverter valve" with a modern 3 position valve and replace the wiring centre with a modern one without the relay.
The tedious bit will be identifying all the unlabelled wires coming into the wiring centre - a task which would be made a lot simpler if I had a wiring diagram.
Does anyone recognise the description of the system and have a wiring diagram they could scan for me (or point me to one on the Internet). The system is of mid 70's vintage (1976 or 1977 I think) and the diverter valve and wiring centre are made by Satchwell. Unfortunately I am unable to see any part number on the diverter valve.