Hi, I am working at a project to hold constant the temp of about 15 liters of watery liquid, which tends to stray down below its ideal 22.6 C by about 3 degrees at night and tends to go up about 5 degrees during one working day (this is to give you an idea of what sort of power comsumption I'll need). Accuracy of 1 K hysterese is fine, even 1.5 K is ok. I'll use two DS1820 to check the temp of the liquid flowing to and again from the peltier
I have a 12 V 8 A peltier and also a suitable power supply (12 V 15 A). I have a heatdrain on one side of the peltier element so that is also not a problem.
The problem is the 2-way regulation of the element. I would have simply used an H-Bridge but PWM to run a peltier is supposed to be a nogo, at least without LC filtering as wavy supply the peltier reduces efficiency significantly.
Mechanical relay may be fine but I was thinking of programming the current to the peltier to drop step by step as delta-K gets smaller. A mechanical relay sending full blast power to the peltier is perhaps not very elegantsetup.
Hmmm, any views?