It is a metal supply from the top, back of the Air Handle, up into the area above the garage. It is covered with a foil covered insulation, from there it goes into flex...everywhere. The cold air return- going into the air handler, is also foil covered insulation, it is from the roughly 2'x2' grill in the hallway....(it's the only cold air return and it is mostly toward the west end of the house.)
With the heat pump running outside, I could grab the insulated suction line and hold it --it was pretty warm but I would not say it was hot. I did grab the copper line, (I moved the insulation around it).
When I flipped on emergency heat, it seemed to be colder in the west end rooms. The blower was not forcing air out the registers, and if I pointed the laser thermometer at the registers it was colder then when on normal heat.
Also with emergency heat on, the suction line was cold.