So maybe no one has tried - anyway I think I may have answered my own question - I really think the volume of water passing would be too small so a 'minor' modification is in order....
I removed the heat exchanger from the internal unit to see how it is configured.
12 loops interconnected to form two circuits, one feed split in the middle (the 3/8" tube) and re-combined by a T connected to the 1/4" tube.
Perfect - disconnect the links at the end where the tubes connect and make 6 individual circuits using 1/4" tube then re-combine them into one.
Next fit the heat exchanger back into the case..
Then cut the tubes to length and combine them into one 15mm tube - the connecting coupler is an 18mm to 15mm reduction.
...unfortunately the case got a bit hot but not to worry as this won't be seen...
Next to test it out....
Acuario