I have just gone through a similar process although my workshop isn't as big, I looked at all sorts and ended up with a infared heater on a tripod I can move around as I work in different places. Apparently the most effecient electrical heater.
The window rattler would have the advantage of dehumidifier and cooling in summer, although I was lead to believe they were banned in NZ years ago due to them having a tendancy to fall out and down onto foot paths.
Bookmarks