Thermal IR (the wavelengths emitted by things around body temperature) is really low-energy. It's hard to focus, and hard to detect, especially with a detector that's already in the same temperature range. Pit vipers, vampire bats and some other animals do it, but the mechanism's fundamentally different from normal vision, and doesn't provide much in the way of an actual focused image. (The pit viper's pit is sort of like a pinhole camera with a really big pinhole.)
Near-IR, the kind of thing that cheap digital security cameras can see, is higher-energy. It can be emitted thermally, but you've got to get pretty hot (hundreds of degrees) to produce significant amounts. Go a little hotter, and you can produce visible light ("red-hot", "white-hot", etc.).
Even near-IR is hard to pick up with a chemical process, though, the way retinal cells pick up visible light. I'm not aware of any animals that can see significantly further than us into the near-IR -- okay, a bit of Googling turned up one fish that can do it.