ᐅ Bring heat from top to bottom

The following situation:
Our underfloor heating in the attic is new, and we are currently drying the screed according to the screed installer’s instructions.
For 5 days starting today, the heating will run at full power.
It will get nicely warm.
The access to the attic is unheated, and I’m considering how to distribute the warm air more effectively throughout the space.
Just leaving the door to the staircase open doesn’t help much because warm air rises, and once it’s at the top, it stays there.

The plan is to set up a fan heater as a fan only (without the heating function).

My question:
Which do you think is better: blowing warm air downward, or blowing cold air upward?
I assume it makes no difference, but I’m curious to hear your thoughts.

What is the benefit? Using expensive electricity for a fan to somehow make use of the heat generated during the necessary screed heating process? Does it even make sense to blow this warm air, which I imagine contains a lot of moisture (@everyone .. or am I mistaken?), somewhere else?

No, you really shouldn’t do that; it would only be suitable for growing mold. ;-)

Besides, the screed won’t tolerate it either. Windows and doors need to be closed. Only ventilate by fully opening them three times a day to exchange all the air.

Unfortunately, the matter has become irrelevant anyway because the wonderful fan – as I just found out – does not ventilate without also heating.

No, the air is not humid. The screed has been drying for several weeks and is supposed to be "thoroughly heated." (there may still be some residual water in it, but nothing visibly damp)
The hallway is never heated otherwise, and I thought it was a good opportunity to give it some warmth.
Well... that will work too...