Is there such a thing as to much air movement in winter? I have a 4800watt fan heater on the floor of my GH and to box fans each end near the roof trying to equalize the temperatures. A lot of air movement .Most of my plants are dormant, any advise would be welcome. (this is my second winter and we have hit 8degs last two nights)

That's an interesting question, Bob - I don't know the answer, but hopefully someone else with more knowledge about it will see your post soon! What kind of plants do you have in your GH?

Adeniums this year is my first try growing them . Aloes have good luck with them ,and cactus, I live in NM have to have some cactus. My problem here is we have a lot of sun year round, in the winter my GH can get to 90 plus in the day, but nights can drop to low teens some times single digits. just trying to save electric, wish full thinking???

4800 watts? Is it a big greenhouse, or lacking insulation?

One or two small fans should provide enough circulation to break up cold spots, most often low, along the base of a wall, or in corners. I'd mount them high, pointed down, to circulate the rising warm air above the electric heater.

Here's a thread on a functional cold-climate greenhouse, built in 2009.
The thread "Low-tech Solar Radiant Heat" in Greenhouses forum