I'm ignorant on this topic.
It looks & sounds to me like an S9 with an upgraded fan.
Is that's what's going on?
Next up, building a case/cover to make it more beautiful somehow.
Anyways, It's whisper silent now.
Discussion
Yes. That's exactly what's going on. Brining down the noise so can run it in the apartment during fall/winter to heat.
Running an S9 is not economic where I live.
Running an S9 instead of an electric heater/gas on the other hand sounds very reasonable. Also given I produce some electricity myself.
Yeah definitely better than running an element based electric heater. At least an S9 produces more than just heat 😉
It doesn't make much sense in my climate (and electricity prices) but it's still interesting to me.
It's amazing the difference a better fan makes to the noise.