I wonder if the impeller might not have been defective in the first place, rather than being damaged by heat after delivery.
I agree, seems like the smoke unit would have to get awful **** hot to melt the impeller thats located in a different housing away from the element.
I would think the impeller would have to be in direct contact with the resistor to melt, that obviously couldn't have happened.
I agree, maybe it was a poorly molded impeller or was damaged during manufacture. If it was hot enough to melt an impeller without touching, you would see signs of overheating on the top of the PCB. G