Why not simply use a hotend cooling fan?

You can, but liquid cooled heatsinks offer some key advantages that can enable you to print hotter and faster than ever before.

A heatsink fan works great for most people. It's a small, lightweight, and quite inexpensive way to disperse any heat that makes it up the heatbreak of your hotend. Seems to tick all the boxes, but if your always in pursuit of stronger materials you'll quickly learn there is a fundamental problem with using a fan to cool a 3D printer heatsink. If you heat the air, it doesn't work anymore.

This problem is not exclusive to actively-heated enclosures, although they exacerbate it greatly. Even passive heating from a heated build plate, depending on the insulative quality of your enclosure, can manage to adequately heat the air inside to a point where retractions can cause heatcreep type clogs in the heatbreak. As an example, in a classical tent-style enclosure, clogs can begin to occur with extended print times maintaining temperatures as low as 300c on the hotend and 145c on the bed. These are classical print temperatures for pure Polycarbonate filament.

This issue puts true high temperature materials completely out of reach due to the need for a heated chamber.

How is it better?

You can't cool a hot heatsink with hot air.

There's no way to cool a heatsink to colder than ambient temperatures with a fan. When the temperature inside of the enclosure exceeds a set point, heatsink temperatures should not exceed 60c acccording to E3D, there is no other economical option than to use a medium to transport that heat outside of the hot zone. That medium is water, or whatever coolant of choice.

When the water runs through the heatsink, the heat is transferred to the liquid cooling loop which transports the water to a radiator. The radiator is then cooled with a fan to dissapate the heat completely out of the system via convection.

What does it take?

To start off, a shopping list.

1. Water-cooled heatsink
2. Compatible Tubing
3. Pump and resovoir
4. Radiator and fan

With all of the items on this list, there is room for personal preferences. Especially with number 1, the heatsink. The heatsink will also be the most expensive upfront cost associated with the change. There are many different offerings for the heatsink, none of which are inheretly better. The Dog River Tools V6 type water cooling heatsink has my endorsment, due to it being small and compact albeit difficult to mount. A more universal offering is the Dragon LC from Triangle Labs, however this is not compatible with the V6 ecosystem of parts and requires shipping from China on Aliexpress which can take a while. This is compatible with the V6 groovemount however which makes mounting a breeze. What can be a major deciding factor is the cost, as water-cooled heatsinks can be extremely expensive, or relatively inexpensive depending on the model you choose.

The heatsink you choose will guide the tubing required. As an example, the Dog River Tools heatsink requires a bowden-to-cooling tube adapter however the Dragon does not since it uses a barb fitting instead of the pneumatic fittings. Massive water flow in not a prerequisite, as the amount of heat being diffused is relatively small. Remember that, if you intend to use this in a heated chamber, the continuous service temperature of the tubing you choose matters. So maybe stay clear of PVC in this case. Silicone and PTFE are the 2 most popular materials. Let the heatsink you choose guide the tubing requirements.

The pump is the literal heart of the cooling loop, as it must be fuctional at all times to prevent heatcreep. Without it, heat will travel up to the heatsink and cause heatcreep and in worst-case scenario premature failure of mounting hardware due to deformation/melting.

Even with that said, it does not have a very demanding job. It simply circulates the water. Water cooling pumps can get expensive, but they don't need to be. Any generic pump that will play nice with you hardware is good enough. Playing nice with your hardware is important though. By that I mean that the volts accepted by the pump should match the output voltage of your PSU. The output voltage is listed on the PSU, and it is the same as the voltage needed when you replace the heating element. If you cannot find the correct voltage, consider using a buck converter to step up or down the voltage so you can use any given pump.

Keep in mind that the pump is a new electronic device being powered by the machine's power supply. Ensure that the PSU has an acceptable amount of overhead to power the pump without overloading it. With most modern machines this will not be an issue.

A resovoir is simply that, it is a small resovoir that the submersible pump is placed in that it pulls water from.

The radiator and fan is responsible for removing the heat from the system. It is a critical part of the build which you cannot ignore. The standard is to use a 80×80 fan and an 80×80 radiator which is easily aquired online since they are commonly used when watercooling PC parts and these will deliver more than enough cooling power for the job.

When assembling these pieces, remember to push air through the fins of the heatsink instead of pulling it. Just like on the orignal heatsink. It is not different. Normally this means that the sticker placed on the fan should be facing the radiator. Another important thing to not is that, when using all the same diameter tubing it generally does not matter where in the loop the radiator is placed. When using step-down adapter to be compatible with bowden tubing, it does. In this case, ensure the radiator is placed immediately after the pump so that it is being supplied water by the tubing with a larger inner bore (not the bowden tube) instead of after the heatsink. This is important so that the radiator keeps full with water at all times. This is beneficial because it ensures that all the possible surface area for heat exchange that can be used is being used.

To start off, a shopping list.

1. Water-cooled heatsink
2. Compatible Tubing
3. Pump and resovoir
4. Radiator and fan

With all of the items on this list, there is room for personal preferences. Especially with number 1, the heatsink. The heatsink will also be the most expensive upfront cost associated with the change. There are many different offerings for the heatsink, none of which are inheretly better. The Dog River Tools V6 type water cooling heatsink has my endorsment, due to it being small and compact albeit difficult to mount. A more universal offering is the Dragon LC from Triangle Labs, however this is not compatible with the V6 ecosystem of parts and requires shipping from China on Aliexpress which can take a while. This is compatible with the V6 groovemount however which makes mounting a breeze. What can be a major deciding factor is the cost, as water-cooled heatsinks can be extremely expensive, or relatively inexpensive depending on the model you choose.

The heatsink you choose will guide the tubing required. As an example, the Dog River Tools heatsink requires a bowden-to-cooling tube adapter however the Dragon does not since it uses a barb fitting instead of the pneumatic fittings. Massive water flow in not a prerequisite, as the amount of heat being diffused is relatively small. Remember that, if you intend to use this in a heated chamber, the continuous service temperature of the tubing you choose matters. So maybe stay clear of PVC in this case. Silicone and PTFE are the 2 most popular materials. Let the heatsink you choose guide the tubing requirements.

The pump is the literal heart of the cooling loop, as it must be fuctional at all times to prevent heatcreep. Without it, heat will travel up to the heatsink and cause heatcreep and in worst-case scenario premature failure of mounting hardware due to deformation/melting.

Even with that said, it does not have a very demanding job. It simply circulates the water. Water cooling pumps can get expensive, but they don't need to be. Any generic pump that will play nice with you hardware is good enough. Playing nice with your hardware is important though. By that I mean that the volts accepted by the pump should match the output voltage of your PSU. The output voltage is listed on the PSU, and it is the same as the voltage needed when you replace the heating element. If you cannot find the correct voltage, consider using a buck converter to step up or down the voltage so you can use any given pump.

Keep in mind that the pump is a new electronic device being powered by the machine's power supply. Ensure that the PSU has an acceptable amount of overhead to power the pump without overloading it. With most modern machines this will not be an issue.

A resovoir is simply that, it is a small resovoir that the submersible pump is placed in that it pulls water from.

The radiator and fan is responsible for removing the heat from the system. It is a critical part of the build which you cannot ignore. The standard is to use a 80×80 fan and an 80×80 radiator which is easily aquired online since they are commonly used when watercooling PC parts and these will deliver more than enough cooling power for the job.

When assembling these pieces, remember to push air through the fins of the heatsink instead of pulling it. Just like on the orignal heatsink. It is not different. Normally this means that the sticker placed on the fan should be facing the radiator. Another important thing to not is that, when using all the same diameter tubing it generally does not matter where in the loop the radiator is placed. When using step-down adapter to be compatible with bowden tubing, it does. In this case, ensure the radiator is placed immediately after the pump so that it is being supplied water by the tubing with a larger inner bore (not the bowden tube) instead of after the heatsink. This is important so that the radiator keeps full with water at all times. This is beneficial because it ensures that all the possible surface area for heat exchange that can be used is being used.

Assembling the Loop

Clarifications and best practices.

For starters, excepting the aformentioned scenario with the large dropoff in flow, the location of a particular component along the loop does not matter much. As long as the radiator is located outside of the heated chamber and coolant is flowing, location does not matter. Neither does getting massive flow rates. Good enough is good enough.

Make sure that you get the right size tubing before you press "buy". Tubing size is generally given as ID/OD, meaning iner diameter and outer diameter. Make sure the pieces you buy are compatible.

Remember that you are adding water to an electrical device, and water causes electrical issues. It's very important that you ensure the loop you have created is as water tight as it can reasonably be. Assemble the loop, fill it with water, and then place the entire system on a blanket of paper towels., This will enable you to detect any leaks in the system. Let it run isolated on the paper towels for a handful of hours to be safe.

Some tips to stack the deck against random leaks include……

• Use clamps or zip ties to cinch down on the barb fittings to further reduce risk of leaks.
• Use Hot glue to waterproof any ins or outs on the resovoir to prevent water escaping in case it tips over.
• O-rings and gaskets are your friends. So is PTFE tape.
• The push-connect fitting rings that prevent depression of the fittings are not optional.