IanD

Lots of cases of people thinking something makes a difference which turn out to not to be the case when actually tested, and especially if they don't know which case they're seeing -- exotic cables, green markers on CDs, gold-plated HDMI cables... You might be right or you might not; other people have said that they make a big difference or none. Proper testing is the only way to answer the question... 😉

The big argument is whether the airflow is actually big enough to make a difference -- some people have said it is, some have said it has little or no effect. For sure those fans are pretty feeble compared to anything else used to push air around a room even if they look like they're spinning fast, so maybe the improvement is mostly down to the placebo effect -- people think it's working so they feel warmer/cooler... 99% of it is heat, and warms the air up -- but there's no extra heat generated, it all comes from the stove, the stove just runs a little bit cooler. 1% (maybe) gets turned into electricity to drive the fan. A DC fan with only a few watts (at best!) driving it doesn't move much air, and I suspect that most of them have well under a watt to play with...

You could get exactly the same effect by sitting a nice big heatsink with no fan on your stove, it cools the stove down by helping conduct heat away from it into the air, like a radiator. An Ecofan does just the same, but it only turns a tiny fraction of that heat into useful power to drive the fan because thermoelectric generation is horribly inefficient. See here, where after optimisation of the design (and you can bet most ecofan suppliers don't do this!) one passing over 600W of heat generated about 8W of power -- so I think it's safe to say that most of them will be less than 1% efficient... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6025646/

That Ecover ingredients list is all standard surfectants and soaps with some degreasing agents and scents, similar to any other washing up liquid...