Quote Originally Posted by Rusty Trichome
A little trick I discovered last year (sometimes it takes me a while) was to have a dedicated fan near the ceiling above the grow, that forces the warm air back down, directly onto the crop. Works great, and not nearly as expensive to keep warm, as without the fan recirculating the heat that has risen.
You know, maybe... another take on this...

You can install a small fart fan on the top, then have the duct run down to the bottom of the room.
Same idea... just, complicating things a little bit more.

Mr. Blue, as Rusty Trichome said, try and do a "dry run".
That will help you nail down the temps.