enlighten me what is a HAF fan


I used box fans for years because they were cheap and easily replaced.
Suspending them from the ceiling or just above the plants or near the heater
was a pain, but they were cheap. In refitting my greenhouse last year with
twin wall polycarb, new exhaust fans, etc, I decided to throw in some HAF
fans. Attached to the ceiling and hanging down about 1' by a sturdy bracket,
the fans made a tremendous difference in circulation. I use 4 in a 2000sq'
greenhouse. The pitch of the blade and size of the motor make the
difference. They are excellent for circulating heat in winter and
dissipating it in summer. In our heat we have to have cooling pads and large
exhaust fans for the heat of the day, but at night or morning you can't beat
those HAF fans (except in price - they're not cheap!).