Is my TEC dead?

[DonNiger]

Just can not figure out, what is wrong. Have 24,6v 172W peltier. And it wount go subzero (cold side).
Just after installing the coldplate, there was no problem to see -20c number (3kg al. rad on the hot side, +45 - +50c)
After installing waterblock on the hot side, it does the best at 10v
At 25v, it still takes around 8 Amps, but the cold side heats up. It is even hotter than water (zero).

IS IT DEAD

[Sam__]

I think there would be some catastrophic melting if it was dead, cos it would act as an insulator and the chip temp would go thorugh the roof in seconds.

[DonNiger]

That is without load.

Water temp 11c
Hotplate 26c
Coldplate 16c

[zipdogso]

That is without load.

Water temp 11c
Hotplate 26c
Coldplate 16c

Your TEC isn't dead.

Those figures are not no load...not to the TEC anyway. What is the ambient temp. If it is 16c or higher that is part of the "load" on the TEC.

It sounds possibly like your TEC needs reseating and clamping.
But I have another theory is 11ºC water the stuff your cooling your hotside with ?

Is 172w the qmax (max. pump) or the Pmax (volts x amps.) ?
If it is the Qmax remember this is at maximum power, under perfect conditions with no load and 0ºC temp delta (difference between hot and coldsides.)

What is wattage of the load your applying ? It should not exceed the rating of the TEC at the voltage you intend to run it. i.e. I don't know the exact figures (don't know what your specific TEC is.) but 10v could easily reduce the pump to 40% of Qmax.

For efficient thermal transfer TEC's need to clamped at a pressure of 150-300 psi. How goods your TIM ? Without clamping the TEC the natural vibration during operation can seriously affect heat transfer.

At 25v, it still takes around 8 Amps, but the cold side heats up. It is even hotter than water (zero).

Reading this again and seeing the sentence above doesn't sound good the coldside shouldn't really heat up. It sounds like the TEC is compromised in some way...not actually dead...yet. The stats for TEC are quoted at a temp. often 25ºC (sometimes 27 or 50.) the max voltage quoted is at that temp on the hotside If your hotside is normally lower due to cooling the max voltage will also dip so you may not of done it much good applying more than the quoted voltage at 25ºC i.e applying over 24.6v.

[DonNiger]

TEC is that one: http://pcpowerzone.com:80/172wpeltier.html

Water is cooled by chiller. In my first post, the water temp was around zero, hotside +16c, coldside +6c.
Reseatng sound the only option for me but, it is not possible to remove the plates (Zalmans adhesive will never let it go). So I just have to make another one ;(

[flak-spammer]

You used an adhesive....??? Not good. The thermocouples in TEC's vibrate and so the best way to attach the coldplate/hotplate is with force. Basically you create a sandwich and the TEC is in the middle between 150-300PSI. That way the couples don't shake themselves loose.

[DonNiger]

You used an adhesive....??? Not good. The thermocouples in TEC's vibrate and so the best way to attach the coldplate/hotplate is with force. Basically you create a sandwich and the TEC is in the middle between 150-300PSI. That way the couples don't shake themselves loose.

Ahesive tried under sufficient pressure.
Anyway, I have to start all over - when I used force to take it apart again, the TEC went into peaces. But the ceramic plates are still atached.