|(this is a two port, that I will fit on the circuit|
in the loft, and I will remove the unreliable
3-port that lives above the heat pump)
During some slightly boring bits of the Nottingham Forest v Doncaster match in which we saw them losing 2-1, my mind wandered off and I realised that if I dump it and replace with a non-return valve (that I took out in May 2010), the system will work more reliably - one fewer electrical part to go wrong.
It will be back to the "trickle while we work" plumbing mode - more appropriate to future installations in other houses.
The really big Plus would be that the future installation of the Kingspan Evacuated tubes is suddenly made a lot cheaper and quicker. The saving in plumber's time will be huge because no pipe will be required to come down through the house to the heat pump. The tubes circuit can attach to the pipes in the loft. They will simply require a 2-port Valve for each circuit, and it will be a Honeywell or another make. I might be able to make use of the existing two dummy ports in the loft circuit.
I will work up a revised circuit diagram of the simpler solution.
It just goes to show..... Sometimes, you think of the best ideas when you are meant to be doing something else!