Martin Brown wrote:

The seals tend to go. I suspect hard winter frosts cause them some grief
too. Mine lasted longer when the greenhouse was heated.

I take the cylinder in for the winter (not going to need venting, and on a
rare bright day, we open the door from "office" to the greenhouse and get
some free heat), and tie the vent shut so winds won't flap it about. We'll
see how much this helps their longevity.

--
Gary Woods AKA K2AHC- PGP key on request, or at home.earthlink.net/~garygarlic
Zone 5/4 in upstate New York, 1420' elevation. NY WO G