Yes. Our fittings use the standardised 1/4” thread according to DIN (G-1/4 inch Withworth), which can be found on all our products (except microSystem, which uses M5 threads (ISO Metric Fine Thread DIN 13-2). In return, this allows the use of every fitting with this thread size on our products (as long, as their width and thread length physically fit).

Depending on the fitting, other sizes may be used as long as they fit. Compression fittings can use all materials in their size, but Push-In fittings require a stiff material, so only PUR tubing or similar can be used without adaptors.

We offer two styles of fittings: Compression-Fittings and Push-In.

There are differences in construction, but not in performance. The Push-In fittings allow, as the name implies, for easy mounting, but they are restricted to tubing made from certain materials. Compression fittings are more flexible because they hold the tubing between a union nut and a miniature barb-style fitting.

Fitting Advantages Disadvantages
Compression fittings allow for very safe operation with a wide range of tubing materials. When using flexible materials, extra costs for 90° connectors can usually be avoided. The installation is more time consuming than with Push-In fittings, as it requires several steps.
This system allows for quick, tool-free connecting of various components and offers high safety when using appropriate materials. Only (stiff) PUR-tubing may be used. This will likely cause additional costs because more 90° connectors are needed.


All of our heat exchangers use copper tubes, making them virtually maintenance-free. If lime deposits, etc. should form, they may be treated like the Heatkiller blocks. Take care, though, that the aluminium fins do not get into contact with cleaning agents – internal rinsing is recommended. The water bearing parts of our pumps are made from plastics and should be maintenance-free as well.

In case of visual damage (e.g. by overheating on pump failure or upon inappropriate reassemble) sealings should be replaced. Matching spare sealings can be ordered from our shop. Alternatively, you might send us the cooler for maintenance. This will include testing for leak tightness.

In some cases, mild abrasives are not sufficient to return the copper to pristine condition. Another approach: Place the copper block (without sealings, stainless steel parts, etc.) in saltwater (or vinegar) and add aluminium foil or bands of magnesia or zinc to de-oxidise the copper. Application time depends on concentration (hours to half a day would be common). Do not forget to rinse thoroughly afterwards!

You will need a bit of distilled / demineralised water, abrasive / polish, clean cloths, and cotton buds. The procedure:

  • Disassemble the Heatkiller.
  • Treat the area to be polished with the abrasive, let it set for a few minutes, and then polish the area in multiple passes with small, circling movements and little pressure.
  • Rinse well with distilled / demineralised water and rub dry.
  • Repeat if necessary.
  • Larger scratches might require preparing treatment with coarser abrasives, e.g. fine sandpaper (grain >1200).

A thermo-electric-coupling element (also known as a Peltier device) is an electric heat pump. It utilises two metals with a differing tendency to release electrons at a given temperature. This creates a characteristic voltage between both metals (Seebeck effect), which changes when the temperature on one side is changed. The Peltier effect is the inverse: If a voltage is applied from the outside, a temperature difference between both sides of the element will form.
The cold side can be used for cooling of a CPU, allowing for temperatures below room temperature (and thus requiring extensive insulation to prevent condensation) - if the TEC is powerful enough. Modules of 100 W and more are usually required to manage the heat of a CPU, the heat input from the environment, and especially the inefficiency of the TEC itself. These high powers might require upgraded power supplies, and they do require a very powerful conventional cooling (usually water-cooling) on the hot side of the TEC, where both the heat of the TEC and of the CPU have to be removed and dissipated to the environment eventually.

Using a chiller or a modified refrigerator in place of a heat exchanger is an alternate solution to using a TEC-element. It does allow lower temperatures (usage of anti-freeze is recommended below 5 °C); however, installation costs (both on purchase and during operation) are usually extensive. This applies to the installation effort as well because every part of the cooling loop has to be thoroughly isolated as it might reach temperatures far below the dew point. It is often more reasonable to use phase change cooling directly on the CPU.

Most important, copper is a semi-precious metal and thus much more resistant to corrosion than aluminium. In fact, the latter one can already be corroded by distilled water alone if no additives are used. Additionally, copper features a 75% higher heat conductivity, thus increasing the cooling performance compared to aluminium. A small table for reference (heat conductivity in W/m*K):

Aluminum (99%) 220,0
Duralumin 165,0
Lead 34,8
Bronze 50,0
Chrome-nickel heating elemet (hair dryer) 11,6
Iron 74,0
Glass 1,0
Gold 312,0
Graphite 169,0
Cast iron 50,0
Calcium Carbonate 2,2
Copper 384,0
Brass 111,0
Nickel 91,0
Platinum 70,0
Silver (pure) 407,0
Steel 45,0
Stainless steel 15,0
Titanium 22,0
Tungsten 177,0
Zinc 112,0

[Values taken from: Kuchling, Taschenbuch der Physik, 16.Auflage ]

This depends on the configuration of the cooling-loop relative to the heat source. A larger heat exchanger surface, increased airflow, and components of higher quality will result in lower temperatures. A fundamental limit is the ambient temperature, which is the lower threshold temperature approached by water-cooling (though it cannot be reached with less than a literally infinite large effort). Even colder temperatures would require thermo-electric-couplings or phase change cooling.

The cooling performance depends on several factors. The heat exchanger parameters (surface size, air movement, structure, etc.) and the cooling structure would be the most commonly optimised ones. If these stay the same, two factors remain:
The flow-rate determines the amount of heat that can be moved from the heat source to the heat exchanger in a given amount of time. This, however, allows for hardly any improvements because the total heat transfer is usually limited by the amount of heat the heat exchanger can dissipate in the same time.
Further, the flow within the cooling structure itself plays a crucial role in the heat exchange between fluid and metal. A faster, more turbulent flow will effectively reduce the distance of water between the stationary first water molecules in direct contact with the metal and the bulk of moving water in the centre of the current. This distance is crucial for cooling performance as it is only traversed by heat conduction but not by the much more capable movement of the water itself. However, this aspect reaches its optimisation limits at relatively modest flow-rates because modern coolers (like the current Heatkiller) simply accelerate the water locally by fine cooling structures and / or jet plates, thus reducing the boundary layer and its effect to almost zero anyway.
The second parameter is the heat capacity of the fluid. It determines the amount of heat actually picked up and transported per unit of the medium, which is turbulently moved through the cooler and further on to the heat exchanger. The following table gives the specific heat capacity for several possible cooling fluids in J/g*K :

Mercury 0.14
Silicone oil 1.45
Benzene 1.73
Turpentine 1.80
Olive oil 1.97
Acetic acid 2.05
Petrol 2.14
Acetone 2.16
Glycerine 2.39
Ethanol 2.43
Methanol 2.49
Water 4.18

[Values taken from: Kuchling, Taschenbuch der Physik, 16.Auflage]

As is obvious, water is already one of the best media for cooling, far superior to all commonly encountered materials. Even considering the heat capacity by volume (mercury obviously is denser than water), water remains the supreme choice and is only beaten by few substances (e.g. pure, liquid ammonia), but neither of these are nontoxic, cheap, easy to handle, and a fluid at room temperature. In fact, most do not live up to more than one of these requirements, if at all.

Yes, if one utilises a heat exchanger of suitable size. Air-coolers need to move the same amount of air to remove a given amount of heat as a water-cooling solution because the amount of heat carried is a fixed property of the air and independent of the cooling solution in use. Water-cooling, however, might distribute this air over a much larger heat exchanger surface, therefore allowing for much slower and less noisy air movement.

Water-cooling utilises water to transfer the heat from its source to a remote place, where it can be dispensed more easily, than in the tight space around e.g. a CPU. Due to the large possible surfaces, water-cooling can be much superior to any air-cooler.

This depends upon usage of the block. Dirt and salts in the water greatly increase the possibility of soiling and should be avoided altogether. We recommend the usage of demineralised / distilled water (optionally with appropriate additives). In a closed loop, problem-free operation for several years is possible, but occasional controls are recommended. Open loops, taking up dust from the environment, and / or loops operated with tap water may require maintenance every 6-8 months.

Of course, the guarantee on material and workmanship remains unaffected. The guarantee on water tightness is voided upon opening of the cooler because we cannot guarantee that the user will not make any mistakes upon reassembly. However, if the cooler is sent to Watercool for maintenance, it will be tested and the guarantee renewed.

Biofilms and other gel-like deposits cause a substantial loss of cooling performance and might increase corrosion in some cases. A thorough cleaning of the whole cooling loop is necessary. An initial mechanical cleaning is recommended to remove as much slime as possible. This should be followed by thorough rinsing, either with soapy / degreasing agents in case of non-water-soluble substances, or (and) with biocides in case of biological contamination (copper acetate solutions >5 g / l, acetone, 70% ethanol or quaternary ammonium compounds are recommended). Check for material compatibility first!
After treatment of the contamination, any remains should be rinsed with distilled / demineralized water.

Calcium carbonate deposition is caused by usage of non-demineralised water and should be avoided! It can be removed with common descalers or acids. We recommend vinegar, citric acid, or bathroom cleaning agents.

Dark areas (copper oxide) are created by chemical reactions between the cooler’s metal and oxygen in the air or dissolved in the water. This process creates a stable and very thin surface coating that usually does not interfere with heat conduction. Copper acetate (greenish colour) is created equally, but includes impurities (rarely encountered in closed loops) which lead to less stable substances. We recommend the removal of copper acetate (see polishing for cleaning procedures). Darkened copper may remain untreated.

Two (and more) heat sources do not require separate cooling-loops. Obviously, an increase in heating power can cause an increase in water temperature if it is not compensated by increasing the surface of the heat exchanger(s). However, even with multiple heat sources the water temperature does usually change by only 1 to 4 °C along the whole cooling-loop, so several coolers can be chained serially without any problem. Very large systems might profit from a more powerful pump to compensate the high flow resistance of numerous coolers, but even systems with a dozen water-cooled components are unlikely to face critically low flow rates.

Fittings as well as the outside of our coolers are maintenance-free and will need no special care. Only the inner cooling structure and the CPU contact surface should be cleaned for optimal performance if they happen to get soiled.

Of course water can be dangerous to electronics. However, there is no medium that would be completely safe over long time periods. Every liquid will slowly gain in conductivity, even if this might just be due to picking up atoms from the surface of coolers. (This is the reason, why e.g. “non-conductive” transformer oil has to be replaced from time to time.) Only continuous, extensive treatment of the fluid would ensure complete isolation. Therefore, all our products are thoroughly tested before selling and the user should keep all connections sealed and check them in case of doubt. Leakages of properly installed cooling-loops are exceptionally rare, making Watercool’s products practically as safe as any other cooling technology. It should also be noted, that even in cases of improper operation the (lucky) user often faces only limited or even no permanent damage to his components. Danger to living beings can only occur, if water is allowed to enter high-voltage / -current components, e.g. the main power supply or the converters of certain lighting systems.