Hi ! This post will be a short overview of the existing offers on Water Cooled HotEnds.

Surprisingly we start to have different offers for Water Cooled HotEnds in the last months and along the year.
Water Cooled HotEnd is not something new, the E3D Crazy Kraken existed for years.

Why ?

Some people are running high throughput printers using large nozzles and they have a problem called "heat creep".

A hotend is having two thermal zones: the cold zone where the filament comes in and the hot zone where the filament is heated and goes through the nozzle. The "heat creep" issue is when the heat propagates through the filament, goes in the cold zone, and then it clogs your hotend because the cold zone is not able to remove the heat quickly enough, and the filament is in a semi molten state that sticks inside the cold zone.
Water is really nice because it needs a lot of energy to change its temperature, this allows to increase the heat slightly, while still having a sharp transition zone from the hot zone to the cold zone, avoiding this clog issue.
High temperature plastics are causing issue at this level too, due to the need of a chamber running at a high temperature where it is not possible to use air cooling effectively (https://steemit.com/printing3d/@boucaron/3d-printing-high-temperature-plastic-requirements).

Overview

• E3D launched recently the Titan Aqua, which is a watercooled version of the Titan Aero. It is a direct drive extruder. The price is high with 122£ (no VAT) without the needed watercooling, you need to add 85£. The quality will stay, and you will forget the price (or not).
  
  • https://e3d-online.com/titan-aqua-hotend-and-extruder
  • You should check also the Titanium Heat Break it is a nice upgrade to improve the heat transfer and reduce the risk of clogging: https://e3d-online.com/titanium-heat-break

• RepRapMe is producing a crazy watercooled diamond.
  
  This hotend can receive 5 filaments, it will be quiet funny to see what they can do with it. It costs 107.60€ + the needed watercooling you have to pay.
  https://www.reprap.me/diamond-fullcolor-hotend-water-cooled.html

• The Opam: https://www.indiegogo.com/projects/opam-water-cooled-hot-end#/
  
  
  As far as I remember the review was not terrible, just for history purpose. It was too early, not yet really the need.

• A recent kickstarter project: https://www.kickstarter.com/projects/1789827891/water-cooled-3d-printer-hot-end/description

• There is a nice DIY where a regular E3D hotend is modified with an automotive silicon hose and few o'ring, this is an inexpensive and efficient way to go:
  
  http://www.instructables.com/id/Water-Cool-Your-3D-Printer-Nozzle-the-Cheap-and-Ea/
  https://hackaday.com/2018/02/06/water-cooling-a-3d-printer/

• René Jurack took the DIY to an engineer level. The price for the E3D WaterCooled HeatSink is 33.5€.

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• You should also check its Titanium Heat Barrier for E3D (21 €) : http://well-engineered.net/index.php/en/shop/titanium-heatbreak

• This DIY from 2014 inspired René, it uses a water jacket from a RC Motor, it is really a pretty nice stuff: https://www.thingiverse.com/thing:247599. The problem is that only a few people really pushing were having the "heat creep" issue. It is a pity that such "gem" was not popular.

• There is another DIY using directly a small aluminium tube of 25mm, with some drilling, hand filing on the heatsink and using some Epoxy or JB Weld: https://forum.e3d-online.com/threads/e3d-water-cooled-mod.53/

Personally, I think the best bang for the buck if you really need it:

• Go for René Jurack's or DIY way on the base of a super cheap E3D Heat Sink.
• Watercooling radiator + Pump + Tank and Silicon hoses from PC industry (cheaper and probably better).
• Put a high quality Titanium Heat Barrier.