Home3D Printer UpgradesWatercooling 3D printers? BIQU H2O extruder kit

Watercooling 3D printers? BIQU H2O extruder kit

Water-cooling is very cool!

The idea of watercooling my PC came to my mind before, I thought about replacing my CoolerMaster Hyper 212 series fan that cools down the CPU of my computer. Water-cooling my Creality Ender 3v2 3D printer? That’s new. Does it make sense? I’m about to find out thanks to BIQU and their BIQU H2O Extruder & Watercooling kit. Is this idea as insane as you think? There is only one way to find out.

What BIQU H2O is water cooling?

BIQU H2O water-cooling kit consists of the BIQU H2O extruder and water-cooled kit. The liquid coolant travels between the tank, radiator and extruder to keep the heatsink of the extruder at the right temperature. On more traditional extruders that job is delegated to fans. They are tasked with preventing heat creep and keeping the extrusion nice and smooth.

It’s not just watercooling, BIQU H2O comes with a direct extruder built-in too. You are getting a nice buck for your money! Until you realise you have to pay twice as much to get the actual water pump, tank and a big-ass radiator.

BIQU H2O extruder

Water-cooling aside, BIQU H2O is a really nice, all-in-one extruder head. At first, $89USD on their store may seem expensive, but if you factor in that you get:

  • high temperature (500℃) hotend
  • hardened nozzle
  • high-temperature probe and heating element
  • geared (7:1) extruder as a direct drive with 7.5kg of extrusion force

Then the price isn’t that unreasonable. I skipped the fact that you are also getting water-cooling technology and RGB LEDs to make it print faster! BIQU H2O is much smaller than the hotends (or whole print heads) on both (Ender 3 & Ender 3v2) of m printers. As it is made of metal, it feels heavy in hand and sturdy.


The direct drive mechanism brings geared extruder with a 7:1 ratio giving it enough torque to pull the filament from any distance away. The attached lever and the surprisingly smooth feeding wheel make the process of changing the filament almost painless.

Anyone printing with flexible filaments or trying to tune down retraction settings will appreciate the direct retraction. Considering the minimal increase in weight, it’s an upgrade that should be welcomed by all of us who want to try more exotic filaments as well as the most popular choices like PLA or ABS.

I know from the omnipresent internet, that the H2 series could be hit or miss on the extrusion end, but BIQU had enough time to address the teething problems (hey, look I made a gear-related pun!), so at this time, I’m hopeful.

A VERY hot end

I thought that my hotend upgrade was pretty good, giving me access to the 300℃+ range. BIQU H2O comes at the 500℃ limit which is simply mind-blowing. This is hotter than my TS80P soldering iron can run at. You could run lead-free solder through it!

To support these high temperatures, much thought went to outfitting the hit with heat resistant components like a hardened steel nozzle, compatible heating element and temperature probe that can withstand that heat without getting damaged.

All that heat, to be able to print with the most demanding materials like PEEK and PEI – filaments that offer fantastic characteristics if your 3D printer can handle it.

BIQU Water-cooling kit

To cool the H2O extruder, you’ll need a watercooling kit sold separately. It’s a set that consists of a pump with a reservoir, a small radiator and a 120mm fan to keep it all nice and cool. It comes with all the fittings and tubing needed to make it happen.

The kit links up to 24V PSU on your printer and steps down the voltage to 12V to power the fan and the water pump. Be sure to use an appropriate coolant. Tap water will only cause you issues in the long run.

As I used the kit to lower noise in my silent 3D printer project, I would strongly recommend spending extra on a Noctua (NF-A12 series) fan to keep the kit absolutely silent.


What’s missing in the box is a mounting bracket. BIQU H2O extruder comes without one, and you are asked to source a compatible one yourself (as in 3D printing a file provided by BIQU). I went all in, and use my resources at work to come up with a very minimalistic holder made of stainless steel. I’m already working on a dedicated replacement plate for my Ender 3 v2 as I have access to decent manufacturing tools.

These 2 blue dots are the RGB LEDs embedded into BIQU H2O

If you fancy RGB-ing your printer, you will need to take care of the RGB LED extension provided by BIQU. This part is optional, but we all know that RGB LEDs make your printer print faster. That will require a 3D controller which comes with a Neopixel socket. I’m using BigTreeTech SKR Mini E3 v3. Sadly, the RGB LEDs highlighting the logo on the side of the extruder feel unimpressive.

Installation – not as straightforward

BIQU H2O is a fancy piece of kit, and chances are, your board may not support it. To make things worse, the internet is absolutely silent (at the time of the writing) about setting up BIQU H2O. I spent a lot of time reading everything I needed and reaching out to BIQU for advice.

Each time I tackle an upgrade or a project, I take the opportunity to increase my tool collection. After all, tools are for life, not just for Xmas! To complete this upgrade, you will need the following:

  • working 3D printer (to print brackets)
  • precision screwdriver – MiniWare ES15 is perfect for this
  • Allen keys (unless you have ES15 already)
  • Soldering iron – I’m using my portable TS80P
  • M3 machine screws
  • JST Connector Kit

It’s a great opportunity to add new tools to your collection, so don’t be shy, I know you are jealous of my precision screwdriver! The list is what I used, I have no doubts you can come up with some workarounds.

Note on connectors

If you watch the video associated with this article, you will see custom connectors made by me, to add and remove heating elements (XT30), thermistors and fans (micro-USB). These are not required, but awesome when it comes to 3d printer service and I have added these as I was constantly swapping configurations for my silent 3D printer project.

PT100 & BTT MAX31865

Apart from the BIQU H2O kit, inside the box, you will find a BTT MAX31865 amplifier board. This small add-on will enable your 3Dprinter controller board to read the temperatures from the PT100 probe correctly. Technically, the PT100 probe is 100Ω and comes with 3 wires (more accurate), however, the probe has been wired to a 2-pin JST connector (less precise).

To make it work, you will need a spare SPI interface available on your controller board. It’s not a problem on the SKR Mini E3 v3 as the board has plenty of GPIO pins I can use for that purpose. If you happen to have the Octopus board from BigTreeTech, BTT MAX31865 simply slots into one of the 8 stepper driver slots. I will cover the installation of the PT100 on SKR Mini E3 v3, but you can apply the same logic with other boards with compatible interfaces.

Unfortunately, the attached instruction isn’t very helpful. It doesn’t help that the BTT MAX31865 has poorly described pin mapping on GitHub, so I made my own help files.

BTT SKR Mini E3 v3.0MAX31865 board

You could use Dupont wires to connect the SPI interface, but I used a small piece of perf board to mount MAX31865 and add a 2 pin JST connector.

PT100 is connected to RTD+ & RTD- pins. Polarity isn’t important for the probe, but you MUST bridge F+ and RTD+ & F- & RTD- together to read the temperature correctly. As I don’t have any provisions to mount the spare board inside the printer, I will simply wrap the MAX3186 in electrical tape, to prevent accidental shorts. As they say, out of sight, out of mind!

PT100 and MAX31865 to SKR Mini E3 v3.0
How to connect PT100 and MAX31865 to SKR Mini E3 v3.0

Something tells me, I will follow this project up with a dedicated case for the controller board, as the wiring is getting messy inside of that small space.

Enabling MAX31865 and PT100 in Marlin

Changes in Marlin must be made as well. I have a complete guide to Marlin already, so I will focus on the important changes to configuration files. First, go to the pins folder and find your controller board. Mine was listed as pins_BTT_SKR_MINI_E3_V3_0.h in the stm32f1 sub-folder. You have to specify software SPI that will talk to the MAX31865 amplifier.

We do that by defining pins in the board pin configuration – add the following to the pins folder:

Marlin: pins_BTT_SKR_MINI_E3_V3_0.h
//MAX31865 module for BIQU H2O extruder 

#define TEMP_0_CS_PIN                       PD9
#define TEMP_0_SCK_PIN                      PA5
#define TEMP_0_MISO_PIN                     PA6
#define TEMP_0_MOSI_PIN                     PA7

Now it’s time to make amends to Configuration.h and Configuration_adv.h

Marlin: Configuration.h
#define TEMP_SENSOR_0 -5

// Resistor values when using MAX31865 sensors (-5) on TEMP_SENSOR_0 / 1
#define MAX31865_SENSOR_OHMS_0      100   // (Ω) Typically 100 or 1000 (PT100 or PT1000)
#define MAX31865_CALIBRATION_OHMS_0 430   // (Ω) Typically 430 for Adafruit PT100; 4300 for Adafruit PT1000

#define HEATER_0_MAXTEMP 515

#define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 400, 932 }

//try these values, otherwise use PID autotune to set it
#define DEFAULT_bedKp 41.78
#define DEFAULT_bedKi 7.32
 #define DEFAULT_bedKd 158.93

If you want to run PID tuning yourself, check my write up about Marlin where I cover this in detail.

Marlin: Configuration_adv.h

and lastly, navigate to the src/HAL/STM32 folder open HAL_SPI.cpp and disable SPI.begin() function:

Marlin: HAL_SPI.cpp
void spiInit(uint8_t spiRate) {
    // Use datarates Marlin uses
    switch (spiRate) {
      case SPI_FULL_SPEED:   delaySPIFunc =  &delaySPI_125; break;  // desired: 8,000,000  actual: ~1.1M
      case SPI_HALF_SPEED:   delaySPIFunc =  &delaySPI_125; break;  // desired: 4,000,000  actual: ~1.1M
      case SPI_QUARTER_SPEED:delaySPIFunc =  &delaySPI_250; break;  // desired: 2,000,000  actual: ~890K
      case SPI_EIGHTH_SPEED: delaySPIFunc =  &delaySPI_500; break;  // desired: 1,000,000  actual: ~590K
      case SPI_SPEED_5:      delaySPIFunc = &delaySPI_1000; break;  // desired:   500,000  actual: ~360K
      case SPI_SPEED_6:      delaySPIFunc = &delaySPI_2000; break;  // desired:   250,000  actual: ~210K
      default:               delaySPIFunc = &delaySPI_4000; break;  // desired:   125,000  actual: ~123K


It’s unlikely that your extruder ratio is the same as the previous extruder. So we have to check and test the BIQU H2O extrusion rate and then tune in e-steps. You can enter the extrusion step value in the configuration file or save it in EPROM. As you are likely building new Marlin firmware for your printer – I recommend hardcoding the correct value in the configuration.h file.

You can either try to do the napkin math knowing that the stepper needs 932steps/min with 16 subdivisions or calibrate the extrusion manually.

  1. Check the existing E-step value in your printer’s menu. Take a note of it.
  2. Load the filament, heat up the nozzle and run it through the extruder until you see plastic extruding from the nozzle
  3. Measure 100mm & 120mm from where filament disappears to the extruder and mark these with a sharpie on the filament.
  4. Extrude 100mm
  5. Measure the distance of the filament left, use the online calculator to get your new E-step value
  6. My new e-steps for Ender 3 v2: #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,400,930}
  7. Rinse and repeat until you are happy with the result.

Fitting BIQU H20

If you already 3D printed a compatible bracket, then the installation is straightforward. As I am using my own, I had to remove the X-axis assembly to access the screws from the extrusion side. Your assembly will depend on the type of printer you are trying to upgrade. Thankfully, you’ll have to do it once.

Part Cooling

As the part cooling solution isn’t included in the kit (it’s a shame), you can download a 3D printable adapter available on the BIQU website, or use my modular design and upgrade to 4020 or 5020 radial fans. They will perform much better, but you will have to spend an extra £10 on a blower of your choice. My personal advice is to go with the bigger one 5020 just in case your filament requires extra oompf! You can grab the files from my Thingiverse profile.

Plumbing – thank God, I’m Polish

I clearly have plumbing in my DNA, as I quickly realised that the water pipes supplied are way too flexible for the setup at hand. I’m lucky enough to work at Labman where we have a dedicated bin with scraps filled with the nice blue airline. After 5 minutes of dumpster diving, I ended up with two 1.5m long 6mm polyurethane tubing, if you don’t work at Labman, then you can grab some from Amazon. It’s perfect for the hotend’s fittings. Depending on how will you route the wires, you may end up with some of them being on the shorter side. The easiest way is to either make connectors or re-use wires from the older hotend as extensions. While on the subject of the cables, you will have to open up the power supply (at the back on Ender 3 v2) to connect the cooling unit to 24V. Pay attention to the polarity.

Filling up is simple, but don’t use water. Get a dedicated coolant from the internet. The choices are great thanks to gamers and PC maniacs. I bought Corsair liquid in blue, as it will fit the colour scheme I’m going with.

Fill up the reservoir and turn everything on. Monitor for leaks with a cloth to your side and the finger near the power button. If you notice any leaks, power down the machine as soon as possible, then tackle the damage.

Keep topping up the tank until the water fills up the radiator and all tubing. Shake the radiator a little bit, as extra air will be trapped there, reducing the cooling performance. Once you have no air in the system, fill up the tank to 90%.

Running a water-cooled 3D printer

I just realized that with a 500℃ temp limit, I could in theory run a solder through the hotend and lay down tracks on PCBs! It’s not a reasonable idea, but an idea non the less. The reality is less dreamy, and nylon with carbon fibre are the filaments of choice. Frankly speaking, I could already print with these after my last upgrade to an all-metal extruder, but let’s face it, you are all reading this cause you are curious about the watercooling part.

Thanks to the water-cooling kit, BIQU H2O removes the need for a high RPM fan to cool down the heatsink on the extruder while a 120mm fan spins away dissipating heat stored in the radiator. Frankly speaking, there is no heat. I’m yet to generate any. After a couple of hours of printing at 275℃, both tubes were cold to touch indicating that the water-cooling system of BIQU H2O is very capable. I ended up downvoting the kit to about 7V (from 12V) to remove the noise from the pump and the fan. The result? The tubing is still at ambient temperature at best.

I clocked about 20-30h of print time near the end of this review, and the BIQU H2O extruder performs as expected. The mechanical extruder pulls the filament uniformly, and thanks to the short distance between the hotend and the extruder feeding valve – filament changes are almost instant. Just do yourself a fav and customise the load/unload length in your configuration file (under #define ADVANCED_PAUSE_FEATURE), as the default values will pull considerably more filament than is required to clear the nozzle.

Final thoughts

There are 3 reasons to get the BIQU H2O extruder. First: you will be the coolest kid on the block (as if owning a 3D printer wasn’t enough). Second: you will enable almost any filament thanks to direct drive and insane 500℃ temperature range. Lastly: you will be able to follow my project to make an absolutely silent 3D printer. If you are looking for the next best upgrade to your 3D printer, give BIQU H2O a go! You are worth it! Let me know your thoughts on the subject in this Reddit thread.

🆓📈💵 – See the transparency note for details.


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