Can I controll the temperature of a Pletier element?

I want to use a water cooled peltier to cool down my processor, but I don't want to reach too low temps in order to prevent condensation!
Let's say my target temp is 20deg. and pelt should come on whenever the temp goes beyond 23deg. and go off at 18deg.
It will be like switching on and off the peltier in every 3-4 sec.
Has any body attempted something like this before?
Is there any faults in my plan such as "reduced peltier life time" ,etc
Any advices/ideas will be greatly appreciated & thanks in advance

Cant you reduce the voltage to the unit?
Turning it on-off a lot may shorten its life.

I have to kick off with mentioning that it probably isn't worth it.
A good water cooling system (such as one able to take the load of a modern CPU plus the pelt required to cool it) will be able to keep the cpu lid at very near room temp
If you don't want to drop below room temp a pelt is only going to reduce the core temp by maybe 5*c, tops.
To keep a 65 watt cpu nice and cool you need at least a 130w pelt at 12 volts, which more then doubles the amount of heat the water loop has to get rid of.


That said, it's totally doable, though it'll have to be completely custom.
The best way would be with a sensor on the cpu lid, and a second sensor out in the case. Then you'd have a small logic circuit or IC (like a basic stamp) that compares them, and shuffles the pelt on and off (or ideally changes the voltage via high capacity voltage regulator(s), but that is more complicated and costs more) to keep them at the same temp.

I think I found a controller,
http://www.peltier-info.com/newproducts.html
I also think voltage control is the best way, otherwise such a tight control of temp is very hard as I know. Any way what I'm thinking is,
I run the peltier at full power as long as I use the comp. and just before shutting down I raise the temp to say[65] so that ice will vaporize.
I don't want to get everything ruined at the first try, so guys those who are using pelts please tell me how bad it is to run an uninsulated pelt in the long run.
I thought the condensation is worst only during the shutdowns!!

When you raise the temp the ice will melt, which of course makes water, which naturally.... drips.

Really, you need to either use a pelt that doesn't go sub-ambient, or insulate everything.
Anything else is just asking for disaster.

Your best off insulating the socket with silicone, neoprene, and dielectric grease and then just letting that puppy cool to its heart's desire. Though i wouldnt use a pelt for 24/7 operation since they are not too efficient in that they consume a lot of power regardless of heat load and as they get hotter they get less effective and consume even more power (like nvidia's fermi LOL)

What everyone said regarding Condensation is true. You either want to insulate or not go below Dew Point. You could also size your TEC correctly, such that it will not provide cooling past ambient. To do this you would need to know your TDP of the CPU and find a TEC that could handle that load at a DT of around 0C at in given input voltage (12v is probably a good choice for a 127 couple module), assuming you are exhausting waste heat to ambient water.

To control a TEC there's temperature controllers as mentioned. Most TEC controllers use an H-Bridge to control the direction of power to the TEC as well as PWM to control the voltage. They use a temperature sensor to provide feedback to the controller.

You could easily setup a system where you apply a certain voltage during certain temperature conditions.

Thermostatic control of a TEC does reduce the life, but this also depends on the quality of the TEC. Some manufacturers will be better than others. And if you go the thermostatic route you could always replace the module after a known period of time.

Thanks a lot guys! Seems like insulation is a must.
One more small thing,
has any one used a forming spray to insulate the mb before?
not powerful as in this vid, but it is available in small cans for about $20.
I'm thinking about using this on and around the water block without using any grease or neoprene. any ideas you guys?

I have used it on some TEC testing that I have done. You can buy it at Home Depot. The one I used is made by Great Stuff, and its blue with a yellow top.

I will warn you, its messy and needs air to cure. If you put on a thick layer, only the foam exposed to air will expand correctly. If you are going to use it, I would practice a few times to get a feel for how it works.

dilra, have you considered phase change? You'll get much lower temps, much more reliable temps, and the cost is similar (once you consider all that TEC requires: controller, PSU, water cooling, etc...). Think about it

There's some really cheap options that do OK...:
http://www.frozencpu.com/products/9...66_939_940_AM2_AM2_AM3_Pre-Order_.html?tl=g49

And there are custom builders all over the world that can make really nice units...runmc @ under-the-ice makes some really nice ones for reasonable prices:
http://www.under-the-ice.com/produc...d=151&osCsid=a18f3c805bc33dfc8f780e5e7746727a

SmittysG35 said:

I have used it on some TEC testing that I have done. You can buy it at Home Depot. The one I used is made by Great Stuff, and its blue with a yellow top.

I will warn you, its messy and needs air to cure. If you put on a thick layer, only the foam exposed to air will expand correctly. If you are going to use it, I would practice a few times to get a feel for how it works.

Click to expand...

On the can it says "Only for one time use".
Do I have to make it in single pass? covering every thin in single pass is impossible! actually how quickly does it get cure!

MIAHALLEN said:

dilra, have you considered phase change? You'll get much lower temps, much more reliable temps, and the cost is similar (once you consider all that TEC requires: controller, PSU, water cooling, etc...). Think about it

There's some really cheap options that do OK...:
http://www.frozencpu.com/products/9...66_939_940_AM2_AM2_AM3_Pre-Order_.html?tl=g49

And there are custom builders all over the world that can make really nice units...runmc @ under-the-ice makes some really nice ones for reasonable prices:
http://www.under-the-ice.com/produc...d=151&osCsid=a18f3c805bc33dfc8f780e5e7746727a

Click to expand...

Thanks for the links, I thought phase change is hell of a job. Seems like it is not
Anyway since I have water cooling already, I think the cheapest option is pelt!

dilra said:

On the can it says "Only for one time use".
Do I have to make it in single pass? covering every thin in single pass is impossible! actually how quickly does it get cure!

Click to expand...

When I used it there appeared to be a set time of ~5 min, where the outside expanded and began to harden. A cure time is not too much longer.

I personally would not use spray foam, my experience with it has been that once applied, it never comes off.

Bobnova said:

I personally would not use spray foam, my experience with it has been that once applied, it never comes off.

Click to expand...

Agreed, its nasty stuff to work with. I have an easier time cutting foam blocks and gaskets.