Posted by Cosmopolite on March 12, 2008, 11:09 pm
I am currently testing my 1 sq.ft. collector, which is glazed with 1 mil
I would like to try double glazing.
Does anyone know what an optimal gap is between the two lites ?
Posted by Jeff on March 13, 2008, 9:53 am
Here's what "The Passive Solar Energy Book" has:
U Values (1/R)
That, of course, doesn't give you an upper boundary.
Now, the same book has R values for air spaces for 3/4" and 4", for
vertical, horizontal and 45 degree. Horizontal has by far the greatest R
value and increases markedly at 4". Vertical and 45 degrees are a bit of
a wash, but are much lower.
All this "suggests" to me about 3/4". At least stay away from very
closely spaced, which would be hard to do anyways!
Posted by Anthony Matonak on March 13, 2008, 4:42 pm
Most double pane windows I've seen don't go much past 1/2 inch spacing.