Seems like in a 'perfect' world, you would put the 'heating tube' a few
inches off the bottom of the tank. That way it would be in the 'coolest'
storage water (but not right *on* the bottom, you want storage water able to
circulate underneath it). And then put a separate 'cooling tube' just below
the surface, in the warmest water. *Then*, stratification would be self
controlling, and you would get the most heat from the tank.
But with both tubes together at the bottom (or top), one is optimized for
its purpose, but the other is in the worst position for its purpose. And
putting them both in the middle would be a compromise on both.
When both are 'active', a couple of valves might bypass both coils and send
the 'heating tube's water straight through to the 'draw off' tube's circuit.
Assuming the two can be mixed.
Anyway, good luck.
We need some ferrous or iron balls in the cooling
liquids and a couple of magnets attached to a hub in
the middle. As hte balls run around the spiralled tubes
the magnets will stir the tank liguids.
VOILA! a magnetic stirrer...LOL
Look out pump!
stratification, so he would
round tank, with
keep the water spiraling
a six foot diameter
pipe with a flow of 3.5
BTU/ft^2-hr-F, and the
thin wall tubing.
For the natural
you need to make multiple
directly over each
be warned, the natural
cold (e.g. below 50F).
numbers quite a bit.