Water heat storage for solar hot air system.

[menaus2]

I have an idea for coupling my planned 150 sqft solar hot air collector to a EDPM lined water tank for thermal mass storage. I'm wondering if the heat exchange method I'm thinking of will be effective.

The hot air panels will be connected to 3 or 4 in pvc tubing powered by a 500 cfm blower. Im wondering if it would be realistic to plumb this tubing in a zig-zag pattern at the bottom of a 500 gal. or so EDPM rubber lined water storage tank and have maybe aluminum fins siliconed to the pvc pipes underwater to aid in heat transfer. Could heat be absorbed into the water fast enough in this setup? How many linear feet of pvc pipe (or similar material) in the bottom of the tank would be necessary to get a decent temperature drop for the air returning to the panels?

I just hope there's a way to make this work as the design is pretty elegant IMO. You could simply raise or lower the water level in the tank to tune the thermal mass amount, and put in a coil of PEX tubing floating just below the surface for hot water preheating.