The sensors of digital camera and camcorders can only pick up near-infrared light such as the IR radiation from IR LEDs and television remote controls. Unfortunately, they can't pick up the longer wave IR radiation, such as that radiated off people, animals, houses, etc. The same applies to IR night vision scopes, which rely on near-IR or amplifying visible light.
So unfortunately you'll not be able to use the camcorder or even an IR nightscope to see a thermal image. This Wikipedia page has some further info comparing near-IR against the deeper IR required for thermal imaging.
As thermal imaging cameras tend to be very expensive, one thing you could try using instead is an IR thermometer. While this will not produce a thermal image, it does do a very good job at finding hot spots. For example, it will clearly tell if someone sat on a sofa or chair in the past couple of minutes or where the heating pipes are located under a floor.