Solar Re-Fit Working

The original system was very much a compromise, done on the cheap just to see if it worked.
Adding a separate coil for the solar hot water means it can be a totally separate system with its own header tank filled with antifreeze to run all year.

I took this opportunity to move the header tank for the central heating, which had been on the loft floor preventing access to this end of the loft.
The header/break tanks are (from left to right) Solar feed, central heating feed, domestic hot water/WC/upstairs cold water feed.
This system is a bit old fashioned and very British, but at least you don't have mains pressure water squirting everywhere.
You will see that I used the old original galvanised tank (inverted) to stand the new plastic one on (this was done many years ago, also the tank would not fit through the loft hatch to get it out), it increases the head for the cold water for gravity fed showers. I built up a wooden support bracket for the other two tanks to keep it neat and tidy.
I've got to finish the insulation and tidy up the vent pipework yet.

The installation is mostly done with plastic pipe which is suitable for central heating systems.
Theoretically the solar panels are an 'uncontrolled heat source', but in the UK they don't get hot enough for it to be a problem.
Plastic pipe doesn't look so tidy but it's cheaper and quick, the whole aesthetic of the pipework is slightly different, the end result having a more organic appearance. (I think Gaudi would approve of plastic piping). In the loft I've just used rubber strapping to secure the pipework, simple, effective, cuts down noise and vibration and is free if you have a load of old EPDM roofing sheet left over.

Refilling the system was a right pain.
First I tried to drain the old water from the panels. I have drain cocks on flow and return lines where they come down into my garage through the flat roof, but with both open I could barely get a trickle out. So I connected a garden hose to one drain cock and turned on the water … still nothing!
It turned out that the problem was the drain cock, the rubber washer had come off inside. Once I fixed that, the panels flushed out nicely.
The water still wouldn't circulate! I opened a joint on the suction side of the pump, nothing, not even a trickle. Ah, maybe it would help if I open the stopcock which I'd installed on the outlet to the header tank?
(You can never have too many stop cocks…or can you?)
I reopened the joint and there was water, but still no circulation.
So I moved upstairs to the hot water cylinder and boldly pulled off one of the coil connections… dry as a bone! I pushed it back on and went round rattling pipes (in a systematic and controlled manner!) Finally I opened that joint again and water squirted out.
The system sprang to life and I could soon tell it will be much more efficient.
There was only intermittent sunshine, but the system was working away warming the water.
The gas fired hot water now heats the upper coil from top to bottom (I swapped the pipes over to achieve this, as it was done the other way round in the old system) so it heats the top half of the tank which means it does it quicker. The solar coil being at the bottom can heat the cold incoming water which means the solar panels will start contributing heat at a lower temperature.

I still have plenty to do, making good, adding all the insulation and putting in the antifreeze.