I'm making a circuit to control the temperature of a peltier element, and I'm trying to figure out the cheapest way that will actually work over the long term, and not burn out my components fast. At first I wanted to just use standard power regulation to control the power to the element and thus it's temperature, but since I need the same side to both heat and cool, I started considering essentially using an H-bridge and PWM as a control. This would kill two birds with one stone I feel. Question is, would this sort of cycle potentially damage a peltier element, or otherwise cause early system failure? My peltier element runs at 10.47 V and 2.1 A. It peaks only about 100 mA above this on powerup. Everything I read recommends not to do this, efficiency and longevity are two cited reasons. But I am not a peltier expert, and am still curious if a low frequency cycle still wouldn't work.