Problem

Other than with the beacon or the conduit, a player cannot instantaneously see wether he is no longer in range or not.
But for this multiblock, it is even more important than for any of the others to know where the exact area of effect is.

Possibilities:

• Item in hand/offhand shows edge if near

Use a torch on the brazier to light it with green fire.
Holding this torch in your hand/offhand will show the borders of the brazier area.