wow fork handles !
I have a very similar contraption but made with smaller pots and a single citronella candle. I leave it on for as long as one candle lasts approx. 2 hrs. The citronella keeps the mossies away and the flickering light keeps the rats away, it doesn't get hot enough to burn through the groundsheet and doesn't produce enough carbon dioxide to kill me (I never sleep with the bivvy zipped up). It might and only might just provide enough heat to provide some placebo heat. I like it on, it pleases me.