[dayjah]

I worked on a scientific instrument a while ago, it had a Peltier heater on it to raise the sample to 60c from whatever residual environment temp was (approx. 20c in a lab). It was pretty amazing to see my old overclocking cooling solution come back around and be used in my professional career some 20+ years later

[madaxe_again]

And they couldn’t use a 100% efficient resistive element because…?

[rcxdude]

The TEC is more than 100% 'efficient' - you get more heat out than power you put in. Though I would guess it's mainly there to get heat control that can span above, around, and slightly below ambient.

[mousethatroared]

Because Peltiers are, at their most inefficient 100% efficient?

At a reasonable delta T you can get 200% efficiencies.

[s0rce]

typically only used if you need to stabilize the temp very close to room temperature or cool it below, unusual choice otherwise compared to a heater.

[nullc]

Even above ambient, being able to reverse direction allows limiting any overshoot.

[madaxe_again]

Yeah, it occurred to me after asking that that’s likely why - with resistive heating you’re bound to have a fiddly time getting a stable temperature.

[s0rce]

If you are reasonably above ambient and the control loop is well tuned things work well, unless you are significantly perturbing the system frequently.

[dayjah]

Honestly, I didn’t ever ask. As the SWE on the project I just had to switch a DIO on/off based on the reading from an AIO. I just trusted that the EE and ME folks were making smart decisions around BOM.