Just go for a drip feed into the bottom connector (with a header tank and ball cock)(cold end) then let the top connector drip to a drain(hot end).
Total loss cooling is easy and cheap, so long as the water is free.
It is and would be easy. My S7's are in my workshop premises and we are on a water meter.
Being involved in energy efficient systems I cant bring myself to do this because of the water loss and costs.
In about 2 to 3 weeks ill post a "How To" with photos of the whole thing and some temp readings.
Further, im going to control the water cooling (Adiabatic) by external temp to further add some efficiency.
Pressurusing the system to maybe 1.5 Bar will also increase thermal heat transfer.
Next is to find a circulator pump that can be run from a small solar array, and battery so the energy to drive the cooling is kind of free.
Im also pretty sure that spraying cold ish water over the external coil wont suffer from the same problem of evaporative cooling would with high humidity.
Most of the time in the UK the unit will run just ambient and should work fairly efficiently.
The big crunch will be when I stick the S9 onto it and take it out of the server room.
Ive also just seen a post on here showing some rack mount shelves that the S7 and S9 fit into perfectly.
Maybe now time to build the internal coil directly inside a spare 19" rack cabinet, that kind of gave me an idea rather than using ducting.
Ive just put a couple of orders out for some raw materials to do this thing properly now that I have had it working.
Looking forward to a proper build, putting up a how to, photos and temp readings.
More importanly solving my heat problem for a low running cost.