HOW TO STACK PELTIERS???????

[MassMurderer13]

When your stacking peltiers, which one should touch to chip first.... a 70W or a 30W??? i have a water cooler on the other side

[Bash]

Originally posted by MassMurderer13:
When your stacking peltiers, which one should touch to chip first.... a 70W or a 30W??? i have a water cooler on the other side

I guess one possible question to ask is: Does stacking Peltier Coolers actually do any good? I can't remember much from my 1/3 of a semester of thermodynamics, but I'd bet that a 70W vs. a 70W+30W stack will come out pretty even. I guess it depends on how well you're conducting the heat away from the hot side of the single peltier...

Assuming that a stack does help, wouldn't it make sense to put the most powerful peltier on the chip so that the chip is as cool as possible? Otherwise you'd get the MOST cooling on the hot side of the 1st peltier, which doesnt make much sense.

-Bash

[jtshaw]

I always thought that a peltier had one hot side and one cold side. If you put the cold side of a 70 watt on the processor and then the cold side of the 30 watt on the 70 watt hot side I suppose that would mean you would have to deal with less heat because you would have only the hot side of the 30 watt left to cool but all in all I don't think it is going to make that much difference.

Originally posted by MassMurderer13:
When your stacking peltiers, which one should touch to chip first.... a 70W or a 30W??? i have a water cooler on the other side

[Cougar]

My opinion is that you're best to use a 70W stacked with another 70W. Stacking two 70W will give about 110W cooling. a 70 and a 30 probably won't do any good at all, probably only give 70.05W cooling

In reply to the post about stacking the 30W on the 70 to give only 30W heat to dissipate, that's a load of crap, where did the heat from the 70w go?

For a 70W peltier, around 140W of heat needs to be dissipated, for a stacked 70+70, you'll need about 280w dissipation, so get a good water cooler.

[Ymaster]

It would not help...Put the other one on the video card.

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[Low Cash]

well.. actually. the purpose of stacked peltier units are to create a larger temperature differential between hot and cold surfaces. the avg. peltier when setup properly will approach around 100°F differential between the hot and cold surfaces. now... to properly stack peltiers you have to make sure the smaller (wattage wise) of the two are still capable of passing the heat developed by the cpu in this case. which is usually 40-55 watts on a nicely overclocked PIII coppermine. then the larger of the two has to be able to pass the cpu watt rating as well as the extra heat produced by the smaller peltier element. no way to be sure of this since it varies with petier material quality and overall construction, but I'd say a 60 watt peltier would produce atleast another 60-70 watts of it's own heat. That leaves us with about 110 watts to dissipate to the larger of the two peltiers. So now we have somewhere around 110 watts PLUS the additional heat developed by the larger peltier (which in this case would need to be atleast 100watt). Ouch! lookin at a easy 150watt load here on whatever is cooling the hotside of the larger peltier. You better have one helluva heatsink . A well designed watercooled setup would suck it up and ask for more . using this technique we can create a much larger temperature differential between the cold side of the smaller peltier and the hot side of the larger peltier simply because the cold side of the larger peltier when properly cooled on the hotside will have a fairly significant temperature drop of it's own.. plus the temperature drop across the hot and cold sides of the smaller peltier unit contacting the cpu. I've stacked arrays create a summed temperature difference of 160-370°F depending on quality of construction and how much thought was put into designing the stack for wattage load vs. wattage dissipation of each layer.

with a setup consisting of a 30 and 70watt pair.. I wouldn't try cooling anything over a celeron 566 @ 850 with it and ONLY if you can get the setup running @ 850 with default core voltage. 30 watt elements are a bit underpowered for most overclocked setups.

Also don't try to stack the peltiers in the reverse order as suggested by Bash. major meltdown waiting there. the 30watt would not be able to pass the heat from the ~90 watt load from the cpu and 70watt element, in effect causing major thermal runaway.. if unattended that setup would eventually destroy the cpu and melt the wires off of the peltier elements (or worse)

[This message has been edited by Low Cash (edited October 21, 2000).]

[This message has been edited by Low Cash (edited October 21, 2000).]

[Bash]

Originally posted by Low Cash:

...
Also don't try to stack the peltiers in the reverse order as suggested by Bash. major meltdown waiting there. the 30watt would not be able to pass the heat from the ~90 watt load from the cpu and 70watt element, in effect causing major thermal runaway.. if unattended that setup would eventually destroy the cpu and melt the wires off of the peltier elements (or worse)

Just to clarify, my suggestion was to just use the 70W...I should not have even suggested stacking them.

-Bash

[Pup]

Originally posted by MassMurderer13:
When your stacking peltiers, which one should touch to chip first.... a 70W or a 30W??? i have a water cooler on the other side

Its normally called 'cascading' the peltiers.

Keep in mind that a Peltier that draws 70W also creates 70W of heat. So you would be looking at around 150W of heat coming off the backside of the stack.

I would put the 70W against the CPU and the 30W to the cold-side of the 70W.

There are lots of uninformed people responding to this post.

Cascading peltiers is a common activity in low-temperature applications but it almost always involves really exotic cooling.

I think it is going to take a carefully designed cooler block, even with water cooling. You're going to want to make sure you have a heat radiator inside the water block to increase the surface area that the water is going to be cooling (like a submurged heatsink within the waterblock). Be sure to used coldish water too because it's going to be stripping a ton of heat off the setup.

I've heard of it done- the most important thing is to keep the CPU dry and prevent freezing and condensation.

If your water setup is efficient, you should get well below zero temperatures.

Good luck,
Eric

[Low Cash]

Originally posted by Pup:
I would put the 70W against the CPU and the 30W to the cold-side of the 70W.

Hrm.. if you placed the 70watt unit in contact with the cpu and the 30watt was in contact with the cold side of the 70watt. Wouldn't that leave the cpu in contact with the hot side of the 70watt peltier?

Not a very good idea.

[Ymaster]

Originally posted by Pup:
Its normally called 'cascading' the peltiers.

Keep in mind that a Peltier that draws 70W also creates 70W of heat. So you would be looking at around 150W of heat coming off the backside of the stack.

I would put the 70W against the CPU and the 30W to the cold-side of the 70W.

There are lots of uninformed people responding to this post.

Cascading peltiers is a common activity in low-temperature applications but it almost always involves really exotic cooling.

I think it is going to take a carefully designed cooler block, even with water cooling. You're going to want to make sure you have a heat radiator inside the water block to increase the surface area that the water is going to be cooling (like a submurged heatsink within the waterblock). Be sure to used coldish water too because it's going to be stripping a ton of heat off the setup.

I've heard of it done- the most important thing is to keep the CPU dry and prevent freezing and condensation.

If your water setup is efficient, you should get well below zero temperatures.

Good luck,
Eric

This is why I don't think it's worth it really..

The only time I tried this was with a sloted cpu and that was just one on each side of a large sink.



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[Memphis]

Don't bother with the 30W peltier. Get another 70W peltier for stacking or use it in parallel.

Other option is to pre-chill the water with the 30W peltier.

To do this, cut a hole in the side of your water reserviour (size of the 30W peltier) and cement a heatsink inside. Fit the peltier to the heatsink in the hole you have cut.

There you go, much safer than stacking.

Cheers

Memphis

[100%TotallyNude]

JEE-ZEE Chryste! You people are insane! "Stacking" peltiers and getting "cool" water... I saw oc'ing as a simple practical skill... but you guys are into it like insane scientists!

[-= HaX0r =-]

You should NOT double stack peltiers, but you can run them side by side with out damaging anything.

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[virusag13]

I agree with 100%, I didn't know people went this far with oc a chip. Wow, guess I should read up on thermodynamics (not likely).