tec temp question

beingblueeyes · Oct 3, 2009

Ok all I really want to slap a tec on something and since I don’t have a lan rig yet I think I’m going to (when I start building it) slap a tec on that. I just got a 400 watt tec from ebay (usa seller if that makes a diff :screwy:

) and after testing I’m kind of disappointed. after 5 min the tec's surface only got down to -3.4F (using laser temp gun) and for some reason I think it should be lower

What I used to test
psu: 700 watt (mod to just run tec)
rad: car heater core
fan: 2 120mm 88 cfm fans
tubing: 1/2
pump: i forget what kind of pump it is
block: swiftech gt water block
TIM: AS5

the rad never got any hotter then room temp (around 68F)

should the temps on the tec face be lower?

after 5 min

Bobnova · Oct 3, 2009

As i understand it ~60-70*f is the largest difference you're likely to see between hot side and cold side, so if the hot side is at 68*f 0ish sounds about right.

Do you have any way to measure it's electrical draw?

beingblueeyes · Oct 4, 2009

Thanks for getting back to me Bobnova, no I don’t have anyway to check electrical draw. If I were to say put another tec on that 400 watt one (stack them) could i go to -60f?

Bobnova · Oct 4, 2009

I'm not positive, but it seems like it.
Course the top tec would have to deal with the bottom tec's 400 watts of heat so it probably wouldn't get the full 60-70 drop, but you should see more drop.
What's cool about a high wattage tec is that it can drag something putting out a lot of heat down to the same 60-70* drop that it pulls a small heat load to.

beingblueeyes · Oct 4, 2009

what im saying is

water block=400 watt tec=2xx watt tec= cpu

ill try this later because i have a 2xx watt tec kicking aorund but i dont have any TIM ....well see what happends

dark bishop · Oct 4, 2009

sorry but thats not gonna work, to do it youd have to have the middle tec be double to handle the bottom tec and its own heat.

Bobnova · Oct 5, 2009

The 200w tec would be overloaded by the 400's waste heat.
The other way around might work, 200 on the cpu with a 400 cooling the 200.
Depends on the CPU though, a high wattage CPU would overload the 200.

dark bishop · Oct 5, 2009

tec are most efficient and effective when used in a separate chiller loop with a lot of smaller tecs run at low power.

Ben333 · Oct 5, 2009

dark bishop said:
tec are most efficient and effective when used in a separate chiller loop with a lot of smaller tecs run at low power.

Where'd you hear that from? I've always heard that peltiers are so inefficient anyway, you should put them directly on what you're trying to cool. A chiller setup might be more ideal for other reasons, but I think the coldest temps and most efficent use of TEC cooling is using it right on the water block.

Also, OP - Why the heck did you clamp the TEC like that? You should really use a cold plate between those clamps and the peltier so you don't crack or mess it up. You also would probably have much better temps. (even pressure = more heat to the block, more cold to the cold plate)

beingblueeyes · Oct 5, 2009

Ben333 said:
Also, OP - Why the heck did you clamp the TEC like that? You should really use a cold plate between those clamps and the peltier so you don't crack or mess it up. You also would probably have much better temps. (even pressure = more heat to the block, more cold to the cold plate)

I clamped the tec like that because the tec would slide off the water block, the clamps are on there with less then 10 inch pounds of force (more to keep the tec from sliding again) I don’t have a cold plate, and don’t have any idea were to get a 50mm x 50mm cold plate. Any ideas?

also tried stacking tecs last night
waterblock=400 hot side/400cold side==200 hot side/200 cold side
and my psu couldn’t not keep up

(whats a "OP")
^^Never mind :Original poster

Bobnova · Oct 5, 2009

TECs are woefully inefficient regardless of how they're set up, it doesn't really matter what you're doing with them they burn an amazing amount of power.

A cold plate is easy, just fine a chunk of metal and slap it on there

Doesn't matter for testing if the cold plate is larger then the tec.

dark bishop · Oct 5, 2009

petras, sidewinders, and frozen cpu all sell 50x50 copper cold plates i think.

beingblueeyes · Oct 6, 2009

thanks for the help gents, now alls i have to do is start pack rating parts

bing · Oct 24, 2009

beingblueeyes said:
... no I don’t have anyway to check electrical draw.

Try read this post -> HERE, hope it helps.

hank123 · Nov 1, 2009

that tec might be a max of 400 watts at 15.4v at 25 amps BUT your not going to get that. the Qmax is what matters. I thing the qmax on yours is around 200-230. so you will get around half of that displaced under a CPU. and you can only get a max of 69C in temp difference between the hot side and the cold side. Now the way you have it mounted is a big problem and part of the reason why you get crap temps.

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