If you like to do things yourself around the home, then maybe a thermographic camera could be useful. No need to look for a power outlet, since it runs on batteries. Just get at it!
From ManoMano
0601083508 gtc 600 c Professional Thermal Camera 12V Bare Unit BSH601083508 - Bosch
Conrad Electronic
Bosch Professional GTC 600 C Click&Go IR camera -20 up to 600 °C 9 Hz