|Circuit diagram for Surya Sunbox|
and Kingspan Varisols
It is odd how the progress of human affairs often moves from complicated ideas that get refined to effective simplicity.
The revised circuit diagram is caused mainly by the failure of the Danfoss, but this has turned out to be a piece of luck as the resulting diagram is simpler and will be cheaper to plumb in - no nightmares of pipes coming through the floor, less risk of system losses, easier for maintenance, and easier to replicate elsewhere. Two solenoid valves will still be needed, but they are cheaper and more easily replaceable in the future event of a component failure.
I have realised that the system will work more efficiently when I return to the 'Trickle while we Work' mode of plumbing. After the heat pump has done a cycle, it continues to move liquid round the circuit to clear what is in it and send to the ground, but it is sending cold glycol! With the Trickle mode, it would recover back to a normal circulating temperature more quickly.
(Note, this circuit diagram is symbolic and doesn't show minor details such as airlock removers or precise details of tees etc. There is still the question of whether I include a water tank in the linen cupboard above the GHSP.)
Postscript: One of my colleagues in the University, Dr Chong, has pointed out that when both the Surya and the Varisols are running there will be a short circuit between the two, and I need a non return valve in the Varisol circuit to prevent this. This is because when they are both working, the Surya pump will work at 5 litres/min and the Varisol pump at about 1 litre/min. So instead of pumping around the ground loop, the liquid will take the line of least resistance, flowing back through the Varisol pump. So the above diagram has been amended to show one.
As the drawing looks more like a London Underground map, I also followed his suggestion to make the junction in the loft look more like a Manifold, and to consider reorganising the plumbing likewise.