It works great for both 10 gal batches (uses both coils) and for 5 gal batches (uses just the bottom coil). I can turn the water off to either coil (though there really is no need to turn off the bottom coil as it's used to cool both size batches). I pieced it together from 2 ICs and (for now) they are ziptied together. I will probably get some copper wire and tie them together that way soon (the nylon zipties will probably get brittle over time).
It has a garden hose 'Y' that connects to the 2 tubing coils using compression fittings and a quick disconnect on the other side that connects to the water hose (which has a quick disconnect too that has an on-off control, nice
). I also have a quick disconnect on the line from my sump pump for ice-water recirculation.Having parallel lines saves water when only doing a 5 gal batch (no need to run water through the upper coil!) and should cool faster when doing a 10 gal batch (compared to a long single coil).
Note: yes the coil sizes are different, but not by design. It just happens that the ICs were different sizes before I put them together and didn't want to chance kinking the line by resizing one (or both).
Click image for larger size.