I was wondering if anyone has added a reflector to the ceiling above the stove?
I have. But not just above the stove, but the entire ceiling.
Back history: Old house. Old ceiling in back room made with reed and plaster. Would have loved to keep the old ceiling (historical**), but it was too damaged. So I tore it down:
Then I put up reflective material across the entire ceiling.
And added a one inch air space, and put up dry wall ceiling.
Finished renovated room:
However, and this in important, for a reflective layer to be effective, it needs to be backed by insulation. I have 8 in (20 cm) of insulation in the attic above that ceiling.
Has the reflective layer helped? Honestly, I have no clue. None what so ever. We never heated this room before we renovated, so have no "before" heating numbers.
But since I had to install a new ceiling anyway, and the cost was minimal to add the reflective layer, I just did it. Thinking... any little bit may help.
If you do not have an insulated ceiling, and wand to add reflective insulation, I would do it around the stove, to reflect IR near by horizontal radiant heat back at you into the room for a "feeling" of radiant heat, and not bother with the ceiling yet.
Hope this helps.
** The rest of the house the reed and plaster ceiling was in excellent shape, so we renovated and kept in place.