The heater is a 10K BTU Glo-Warm non vented heater. There is a control knob on top that is variable from pilot to high(10K) with four positions. I set it on position one unless the temps are going down to zero or less, then I will set it on position two. The burner is about six ins long and about one ins wide.
As soon as I entered the GH, I knew everything was ok. The temps were at 54F and the RH at 64%.
The Polycarb panels, PVC frame and Neoprene weather striping are doing there job. The tomatoes are growing up against the roof with no ill effects. John