Some advertise they will increase temperature 20 degrees over ambient at max flow rate. 

Seems if it was in between your ceiling and the roof, the ambient temperature from your unit would keep it from freezing.

Ambient light from the window is 100,000x more bright. 

Today it was -18 and my heat pump had error code p3 which is “ambient temperature too low for compressor to run”.

There is a drop ceiling in the efficiency (and I'm actually looking at next yr adding a layer of drywall or sonopam to the ceiling) however, I explained to them that with the cold and a 120 yr old house that ambient noise can be a little more in the winter. 

Usually about a 20 degree difference from ambient is the best any system can accomplish.

It floats around in the ambient air, doesn't it?

The rest of the room will be ambient room temp.

Warm, humid air blows through and hits surfaces that are cooler, closer to ambient ground temp. 

I'd also be intrested in seeing how this turns out lowering the ambient temp and what not.