Building a cheap chiller – Steve Chancellor (Stevo)
Having an interest in computer cooling for some time now and a passion for engineering (I run a busy specialized engineering company here in New Zealand), I decide to change my current water-cooling set-up to something a little different, so to speak. All my water blocks (CPU,chipset and video card) are made by myself, as are all the mods and fittings to my case etc. I guess it helps having all the tools to play around with.
My first task was to construct a Perspex water tank 780mm long x 160mm wide and 600mm tall out of 10mm thick Perspex:
This was basically glued together and will hold about 50 litres of distilled water at the desired level. Barbs are screwed into the sides of the tank for water inlet and outlet.
I managed to find a very reasonable pump for around $35 USD, rated at 1000l/h @ 1.95m head, which works very well in this set-up.
A temperature monitor is attached to the tank which shows the ambient temperature and the water temperature together. Perspex is rated to survive at – 30 deg C and + 80 deg C, so its perfectly OK to use.
The next task was to submerge the inner cooling unit from an old fridge into the tank:
I managed to find such a perfect candidate from looking through the second hand goods in the local newspaper. For around $10 US, I got an old beat up fridge about chest high. After tearing it apart to reveal the inner workings that I wanted, I fired it up and it worked perfectly first time.
At this point I should mention that this whole project could have been done VERY cheaply if I so desired. For example, I didn’t have to go to the extent of making a fancy tank, as a foam box would have worked well or if not better as it would be more efficient in its insulating properties and the next part would have saved a lot of money. Another simple idea would be to leave the fridge as it was and place a tank inside it.
I decided to cut the line feeding the cooling coil unit, therefore releasing all the gas [ed note: Illegal in many countries]. My reasons for doing this was that I wanted the lines to be flexible so I could easily install it into my tank over the side, allowing me to move the unit around if I have to.
It also allows me to place the cooling unit in other tanks, etc., at a later date if I want to because it’s not fixed. A local company here in Auckland took care of the re-gassing and fitting up of the fridge unit again with the flexible hoses.
So if you’re motivated by such a device, remember you can do it VERY cheaply if you want. The workings of the fridge are mounted in a plastic box, which is air cooled by a 240v fan and also hosts the thermostat which allows me to dial in my desired temperatures, same as any domestic fridge. I have it set around about 10 deg C at present and have had it cooling down to 3 deg C no problems at all.
You will of course realise that even without the fridge unit working at all, the sheer volume of water in the tank alone will take some time to heat up, without any assistance to cool it. Note that in the circuit that I’m not using any radiator to assist in cooling at all.
I’m not obsessed with trying to keep it too cold, as problems with condensation could occur around the lines and blocks depending on the water temperature versus the ambient temperature and the humidity level. A heat index calculator is available here., or a chart
The idea is to have cool water at a maintained temperature to allow an almost dead silent system.
This has been achieved because I have the fridge unit, which is very quiet
outside my computer room. Having 50 litres of water in my computer room with a disaster on the carpet would NOT! be great.
I have the unit running in my garage and the silicon hoses run through the walls into my computer room. The whole unit fires up with a tap of my keyboard as my PC wakes from the keyboard. A simple 12V relay switch powers up the pump and fridge unit.
All the lines are silicon, as it is easy to work with and no hose clamps are required at all. Silicon hose is robust and the grade I’m using is rated to last 150 years! If it fails in around 140 years I’ll take it back and get a refund!
All of my blocks have been made from aluminium with Perspex tops. You may have seen a picture or two of my P4 block on the net before with my previous set-up, but the chipset block and video block, which cools my Radeon 9700, have just been made:
This is all running inside my modified tower case:
The reason I use aluminium for my blocks is because it’s light, easy to machine and can be spark eroded, which is one of the processes that I used on my P4 block. Having a heavy copper paperweight hanging off my brand new video card, ready to snap, doesn’t excite me.
The other reasons are that the P4 is not a great heater anyway and most will overclock well just on air, even with a stock heatsink, so cooled water running through this set-up is more than adequate. Even with my previous water-cooled set-up with no additional cooling other than radiator, I could achieve some good overclocking results, so this is even better.
The results are fantastic. Basically I can dial in what temperature I want (within reason) with about a 3 degree C differential before the thermostat will kick in.
I’m able to run games, or any other programs for that matter, with the cooler unit easily able to keep the temperature to my desired level. My current setup is an Abit BD-7 Raid with a 2.53 CPU @ 157 FSB (2983 MHz). Unfortunately, my current CPU is not a great overclocker and won’t go any higher.. some do ..some don’t.
The temperature monitoring on some of the Abit boards is well known to be rather erroneous (to put it mildly) so I placed a temperature probe as close to the CPU as I could. I modified the end of a simple temperature probe to reveal the temp diode, shortened, resoldered and insulated the bare wires.
I then drilled a hole into the end of my waterblock so that the probe will sit in a position over the middle of the CPU.
This gives the following reading:
- Current ambient temperature = 18.3 C
- Water temperature = 11.2 C
- Probe reading in waterblock = 13.1 C idle CPU
- Probe reading in waterblock = 15.9 C full load CPU
This is compared to Winbond Hardware Doctor program, which ships with the Abit Motherboard. Not that there is anything really wrong with the temp monitoring program, as I believe its all to do with the “crappy ” diode monitoring itself.
Seems that the other Abit boards suffer the same in accurate temps too – Go Here for a discussion in the Forum.
My “Winbond Hardware Doctor” reports temperatures around 20 C + to my own readings. I’m not totally over-obsessed with what’s right or wrong here and accept that even my own monitoring could be incorrect, as it is only close to the core. However, the purpose of my project was to achieve a unit that will pump cooled water with an almost dead silent system, and all the time being somewhat slightly unusual.
Feel free to contact me with any questions.