Just googled Pex tubing and it sounds impressive stuff. It...

Just googled Pex tubing and it sounds impressive stuff. It should last forever as it's well below the 120 - 150c max it's rated at.
Have I got it right that the Edson tank water flows through the evacuated solar tubes, the floor and the wood boiler but the hot water for the house taps comes from a heat exchange coil in that Edson tank? If that's correct have you treated the water in the tank with anything to help keep it clean and stop corrosion?

I also had a gravity feed tank in Tasmania. It was about 250m from the house and I used binoculars to check the outside level gauge to save the long climb. If it was low I hit the switch and the old pump 100m away in another direction would start thumping away pumping water from the soak fed by 3 springs up to the tank on the hill.
The old guy I bought the place off insisted on showing me how to strip and rebuild the pump but after scraping the leaches off I started planning for a solar powered replacement. Of course I just kept using the old pump hoping it didn't crap itself.

I've never heard of gravel being used for a pad before, only sand.

To find out where the heat is escaping and getting in during the summer try one of these for $12 delivered. I've had one for ages and for $12 it's ridiculous value and lots of fun. It's a real laser beam so don't let kids get hold of it.

http://www.ebay.com.au/itm/Portable...944837?hash=item236a0ac045:g:PX0AAOSwSWJXRWPg

This house has big single glazed windows, over half down to floor level too. Luckily SW WA coastal areas are quite temperate. By choice I would also have double glazing and have all the floor level ones bricked up to normal height.

I should have said the air control. No flue damper in hers or mine.