Greenhouse: Heater placement?, 1 by Badseed

Badseed wrote:
I hope this hasn't been covered...

I've always had a heat source that I could move. This year I bit the bullet and got a nice big honkin' propane heater. Wherever it ends up will be it's permanent home.

My greenhouse is 8.5x25 with double doors at both ends. The heater does have to be 18" out from the wall. What I can decide is whether to place it at one end or the other or in the center somewhere? I'm sure I should read the heater info more intently but what is the line of thinking when you have a long narrow greenhouse?

Googling really didn't help me but I did see some really nice greenhouses. LOL I'll for sure have a potting bench and I'm also considering putting in a sink.