We made and also used 3 of them last year. In the context of energy costs, I would use them again, partly because it really works. I saw the thermostat rise by 2 degrees over time. But after all the negative reports, incendiary photos that I saw passing by, we have now opted for something else. But either way, it certainly works.!
And even more dangerous! Incomplete combustion, i.e. particulate matter and carbon monoxide! And one of them also caught fire and clapped this week.! It's no use, but JUST DON'T DO IT