I'm in the process of putting together something, but I just keep going round in circles. I have two separate solar set ups. UFH and trying to connect a Willis immersion heater. Which does work (manually at the moment) LPG combi boiler for heating and hot water. I do have a log burner, but logs are getting expensive now and it would be nice to be a little greener.
So, buffer tank to pre-heat the water to the boiler? Its all the routing with the suitable relays and switches I can't get my head round.