The flame in #60 is still my favorite. The colors in #75 are good in the daily work. I am afraid, gradients and shadows look "shitty", if you go down with the resolution - which you sometimes have to do (e.g. favicon). Can you please combine the flame of #60 with the colors of #75?
Up to now, I feel fine with the house-issue and the heating-theme. The only thing I ask you to think about is the electricity thing. Do you see a simple way to symbolize this? The sparks/flashes of some other designs look to agressive from my point of view. Mabe you find a way to integrate some kind of "rotation" (theres is always an engine or at least a generator inside of a bhkw) without ruining the design.
Thanx!!