We put our foggers directly upstage of the edges of the
proscenium (we've got a pair of
Martin Magnum 1500s). On a good day, the
smoke just blows right out and covers the
stage. On a bad day, the
fog goes about 2 feet onstage, blows back into the wings, goes up to the top of the
grid (we don't have a fly
system, so its about 30 feet), blows out over the
stage, and then descends just below the
grid. Looks cool, but takes forever to do.
We also built some
fog cooler boxes. Basically, we just put the foggers right up against the boxes, which are about 18" x 8" x 12". There is old vacuum pipe coiled up inside the box that the
fog flows through, and out the other side. Before each show, we just load up each fogger box with dry ice to cool it off. Styrofoam
insulation ensures it lasts for the whole show. It makes a really cool
effect.
Anecdote: Whilst we were testing this
system, one of the dancers came up to the TD and I and asked how we made this cool
effect, saying: "Is this liquid hydrogen?". I told her "Yes, light a match and watch." She didn't believe me, so then I told her it was just plain cold
fog.
Dancers. Almost as bad as actors. Their only saving grace is that they don't have the ability to wreck a set.