Originally Posted by OCAddict Warning: Spoiler! (Click to show)
Information brought over from the original thread:
Caution: Peltier cooling will allow you to go below ambient, depending on what your desires and goals are and how many peltiers you run, you can even go below 0c, it is possible using anti-freeze coolant. My initial goal was to be able to run below ambient just above the condensation forming point so motherboard insulation does not come into play. You can safely enjoy about a 13c below ambient without any condensation worries at all, but you take full responsibility with what you do with this information.
I’m sure the first question would be why would anyone be interested in this type of cooling in the first place, and if you’re 100% satisfied with your present water cooling setups load temperatures, you won’t be. The main why is, it can run load temperatures, lower than the mass majority of your ambient reliant CPU big air coolers, CLC Coolers, Standard and Custom water cooling loop idle temperatures.
In my own words, The peltier is a simple device, you run electricity through it and the reaction between the two dissimilar metals results in one side getting hot and the other side getting cold, if you do not cool the hot side it gets too hot, overheats, and burns up, simple as that. The Peltiers cold side thermal output can be harnessed and used. In this case the cold side is being used to chill water flowing through a modified water block and storing that chilled water in an insulated reservoir, which is then used to cool a CPU.
The peltier itself is essentially a miniature marvel that has been used in various applications like a freezer or heater or it can also be an electrical generator when hot and cold are artificially applied to the peltier it will actually generate electricity, and with no moving parts to break down, the key is discovering how to use what it can do, to your advantage. presently the hot side exhaust is being used to heat my office and in the winter it does a very good job of it, in the summer I have to run my office AC anyway so it counters the added room heat from the TEC assembly.
In this situation the peltier is being used to generate useable cold output.
When the CPU (overclocking), cooling community first put the peltier into operation it was directly mounted on the CPU usually water cooling the hot side, which brought side effects requiring motherboard insulation to keep from shorting out components from the ice forming around and on the backside of the motherboard socket.
Ice occurs when the surface temperature is cold enough to freeze the moisture in the air, the more humidity in the air the worse it would be.
Comparatively those earlier CPU peltiers were only a small percentage of the size of the peltier being used in this project, which is a Potted Peltier, measuring 50mm x 50mm x 3.10mm, wattage = 226w ~ 245w, amperage = 26a max, voltage = 12vdc ~ 15.4vdc, with a maximum operating temperature of 125c.
However I am undervolting the peltier and using a standard PC power supply, a Silverstone 1000w 80a single 12v rail, the peltiers will be supplied with 12v instead of 15.4v which changes their output specifications to 200w at 20a, this will allow me to use a heat pipe air cooler to cool the hot side of the peltier.
Note: Potted means insulated, some peltiers are not insulated at all and really are not suitable for this type of cooling, you would want to acquire a potted peltier.
Many here at Overclock.net use direct to CPU mounting methods today and if you're interested in that type TEC application you can research further in the Peltier/TEC section.
This thread is totally about using the Peltier/TEC assembly to replace the ambient limited radiator cooling, with a chilled water cooling solution allowing going below ambient room temperature.
Logically it would seem the best solution would be to keep the hot side as cold as possible, but that's not the case, you have to allow the hot side to get hot for the cold side to get cold, but since we're only talking a approximately 1/8th inch thick peltier, that's a very close distance to play the hot/cold balancing act.
Some of what needs to be shared is the peltiers what I call weirdness, I originally thought the cooler I kept the hot side the cooler the cold side would be, however the hot side has to get hot for the cold side to get cold, it is a perfect example of, "For every action there is an equal and opposite reaction.".
There was quite a bit of testing and fan changing to get the peltier to run at it's optimum cooling side capability, at one point I actually had the hot side too cool and it was not performing as expected, it's been a learning experience that's for sure.
Warning: Spoiler! (Click to show)
Simple discovery the hot side can override the cold sides effectiveness but news flash the opposite can also happen, the cold side getting too cold, can override the hot sides effectiveness,
So you're after a balancing act of hot and cold to get what you're after, the true key to this things performance is give it the heat range it operates best within or sweetspot, and it will give you the results you're looking for. It needs to be in the mid range of it's capabilities, so it's hot enough to deliver the cooling performance, but far enough away from it's limitations to keep from burning it out.
The simple key to keep the peltier from stalling out and constantly producing cold for you is removing the cold the peltier is producing as fast as possible so the cold side of the peltier does not get too cold and affect the hot side, that is exactly why this setup works and has been working for over 3 years.
Power Supply Information:
If you decide to use a PC style power supply, a single 12v rail is what you need to use to power a peltiers constant load, and make sure it has the raw amperage handling capability, well on the plus side. (Do not use a multiple rail power supply!)
With a PC capable P/S 12v, you will need to get power from 14g main wires, like from the 8pin or 4pin motherboard connector, or the PCI-E connectors as those are usually 14g.
Danger: Do not use the 18g 4 pin molex connectors as they cannot handle the load, they will burn up and take the power supply out, and more than likely anything else hooked to it.
Additionally do not compromise this power supply selection, to be on the safe side you need amperage capability higher than the peltiers load.
When it comes to powering a peltier you have to get your power from an output area of the power supply that can handle the amperage load. I used 2 yellow positive 14g wires from the 8pin motherboard connection line soldered together, as the positive primary, and 2 black 14g negative wires soldered together as the negative secondary to power mine.
You do not have to use a power supply readily PC available you can find online specific voltage/amperage rated models that will be specifically what your peltier requires, the challenge with those is getting them to power when the PC powers up or down.
The power supply in the TECBOX is jumpered to the power supply in the main computer, when the main computer is Started Up or Shut Down the TECBOX power supply does the same.
The most popularly used power supply that is not a PC power supply is the Meanwell.
Cooling the Hot Side:
Cooling the hot side of the TEC is a challenge in itself, seeing as how it's best performance comes from allowing the hot side to get hot, however the maximum heat range for my TEC is 125c which is 257f, way past the temperature to boil water. I originally thought water cooling the hot side of the peltier was a good idea since in it’s earlier days it was water cooled but much smaller peltiers were being used, nowhere near these capabilities.
In my attempt to water cool the hot side, the radiator got so hot I couldn't put my hand on it, the XSPC water pump got so hot I burnt my finger on the metal output spout. At that point the peltiers hot side temperature reading on the outside was 160f, I estimate about 180f in the center of the peltier, cooling that much heat is serious and in itself takes a serious dependable and capable solution.
In my early ignorance I was in my experimental time period of desperation as I only had a thin 240 rad to cool the hot side and that was not enough, so what I am saying is you absolutely can water cool the hot side, but you have to have enough radiator to get the job done.
With water cooling the hot side of this higher amperage peltier seemingly off the possibility table I turned to heat pipe air coolers, the first was a shelved Tuniq Tower (the original model), with only 3 heat pipes, it just could not overcome the heat the CPU was adding to the water.
I had a Thermalright Ultra 120 Extreme on the shelf and used it to cool the hot side of the peltier, it has 6 heat pipes and is very effective at handling the heat produced by the peltier, also an old Xigmatek S1283 HDT cooler works very well.
I experimented with multiple combinations of fans in push/pull configuration and settled on 110cfm Sanyo Denki San Ace 120mm fans running full out.
A good heat pipe air cooler can and will cool the hot side, however my choice reasoning was to choose coolers that could still handle the heat load if the cooling fans completely failed. A heat pipe cooler that is on the cooling performance level of the TRUE (Thermalright Ultra Extreme), or the Noctua NH-D14, is sufficient remember the TEC will burn up if it is allowed to get too HOT.
However the heat pipe air cooler only works because the peltier is undervolted, it is important that you the reader understands that.
Modified Flow CPU Water Block
The Swiftech Apogee XTL is the best water block for flow modifying to use with a 50mm x 50mm size peltier, I'm recommending it over the XSPC Rasa, the Rasa will still work, but not as well as the Apogee XTL.
Due to the XTLs larger copper base plate the entire 50mm x 50mm peltier fits in solid contact fully covering the contacting face, whereas the Rasa base plate is exactly the same size as the peltier, requiring filling the screw indents with thermal compound.
The Apogee XTL is exactly the same design of the original Apogee XT, but the top is machined from black delrin, which is much easier to cut and modify, and is also cheaper, the copper base is wider allowing further coverage and cold pickup of a 50mm x 50mm peltier.
Pictures are posted in the above post as to the water blocks flow modifications.
After many trial and error experiments I settled on an insulated reservoir I made from 4" PVC schedule 40 pipe, insulated with aluminum faced foam duct seal, as the best solution to arrive at the proper balance of water mass vs peltier cooling capabilities. From the beginnings of this testing (Referenced in the Below Ambient Thread), using a 54qt 13.5 gallon down to the present ½ gallon or 2 litre capacity. Using a lower volume of water reducing the thermal mass, allows faster cooling transfer to the water.
The insulated reservoir becomes a cold water storage tank which becomes the buffer the TEC cooling needs, allowing the peltier/TEC assembly to counter, and lower, the heat generated by the overclocked CPU. Additionally all the tubing runs are insulated to retain as little cold loss to the ambient room temperature and heated operational elements inside the machine.
Performance Variables :
Water Flow Rate :
Water flow rate affects the cold conduction of the peltier to the water flowing through the water block, too fast and the water does not get cold fast enough, too slow and the block can freeze, presently set on level 2 of 5 settings using a Swiftech MCP655 pump. Flow rate is also a consideration when balancing out the system, regarding taking into consideration the CPUs water block flow restriction. The perfect balance is having the peltier water block able to completely counter the heat the CPU is adding to the water.)
Peltier clamping pressure:
I started with about approximately 25psi ~ 35psi estimated which is basically a standard heat sink clamping pressure, then increased to approximately 50psi+ then after discovering on the net even higher pressure was needed, increased to approximately 100psi.
I'm saying approximately 100psi because I have no actual way to gauge the actual pressure it is wrench tight though, way past any spring clamping.
Addressing Condensation :
Where you live has everything to do with at what water temperature condensation begins to form on the CPU water block, regarding relative humidity, and dew point. Where I live condensation begins forming as a frosty look at 8c water temperature which is 15c below ambient and 16c ~ 18c below the best water cooling radiator loops and as long as I stay above an 8c water temperature condensation is a non issue.
I have an AC unit in my office, that tends to keep humidity levels down quite a bit and allows lower non-condensation freedom. Additionally you can use positioned cooling fans to evaporate the condensation if you need to go lower but by the time you drop down to about the 3c range of water temperature the condensation builds too fast even for fan drying. The fans can actually blow drops of water from the block, and of course that is bad!
Juggling the Hot and Cold:
The cooler/reservoir also allows running the TEC at a cooler hot side operating temperature, and that is controlled by the fan speed on the heat pipe cooler, I know that sounds weird, none the less it's 100% true. Getting what you want from the TEC is a balancing act, you have to let the hot side get hot, for the cold side to get cold.
That is a testament as to how good the Thermalright TRUE actually is, that it can make such a cooling difference and control the hot side temperature with no voltage adjustment to the TEC just controlling the fan speed air flow.
Radiators and Peltiers in the Same Loop:
Many had suggested that would be a good idea which turned out to be a bad idea, the bottom line is the radiator raises the temperature of the chilled water, why go to the trouble and expense to chill the water then allow a radiator to undo it. It seemed like a good idea at first, the radiator could add some stabilization to the loop when actually, it did quite the opposite.
So been there done that, with that idea, and if you're thinking it at this point, forget it.
There's no need to go into any in depth explanation of the whys and wherefores, it is just counter productive to a chilled water cooling period!
Most of this was learned the hard way and I hope it helps you.