Nothing is better than an answer that says there is really no hard and fast
right answer. Keep the answers coming. I will let you know when and if I
tear a hole through the outside to pump it in.

Dave

"Steve" wrote in message
...
David Jewell wrote:
I put a greenhouse up this summer and am confused about a point and was
wondering if anyone could answer this one for me. I currently inflate
the
greenhouse with air from inside the greenhouse but have been told I
should
be drawing air in from the outside.

With drawing the air from the inside I am thinking that the bubble will
be
warmer and give me better insulation but I am concerned with the issue
of
water collecting in the bubble. With drawing air from the outside I am
thinking that the air will be a lot colder and thus not so good for my
orchids.

Any advice would be greatly appreciated.

Dave (Ontario, Canada)

I don't have a greenhouse but I recently had a discussion with someone
who was having a problem with moisture and algae growth between the
layers. He was using inside air.
In the winter, the warm inside air will hold a lot more moisture than
the cold outside air. That moisture can condense when it is next to the
cold outer plastic. If your system is extremely air tight, you can use
outside air with almost no loss warmth because you are not actually
pumping much air in. You are only applying pressure to the air that is
always in there. If your system is leaky and you actually are pushing in
a lot of air, then inside air may be better. The air circulation from
the air actually moving through the layers will help keep moisture from
building up.
Obviously, either way will work.

Steve