[thedoc (OP)]

Alan Torley asked the Naked Scientists:
   
Why can I not use my existing geyser (Hot water system) as a solar geyser in a thermosyphon split solar system where the panels will be 300mm lower than the geyser.
No pump allowed must be thermosyphon.
The geyser has an inlet and an hot outlet.
What do you think?

[wolfekeeper]

I'm not sure what a 'geyser' hot water system is, but themosyphon is a standard technique for solar thermal water systems, although off-hand 300mm sounds a bit marginal on the head to get good circulation.

You normally want the solar panels to be a separate circuit to the actual water (and incidentally full of appropriate antifreeze for wintertime), otherwise it will scale up.