Late last summer I completed the construction of our 14′ x 20′ greenhouse. I decided to build the greenhouse from scratch instead of buying a kit because I really didn’t like the fact that the kits don’t allow for the sides to be removed or in some cases open at all. This doesn’t allow for adequate ventilation unless you have fans blowing and they certainly are not conducive for allowing pollinators easy access to flowering plants.

And now that spring is here, the greenhouse was getting quite warm with afternoon temperatures approaching 90ºF. I did build-in seven hinged vents near the ridge-line of the greenhouse, but had not mechanized them to open as temperatures increased. I did however purchase two Univent automatic greenhouse window openers on Amazon over the winter and decided to give them a try.

The Univent openers automatically open and close based on temperature and require no external power. A threaded rod filled with paraffin wax, expands and contracts with heat and a piston pushes/pulls on the Univent’s hinge. The rod is threaded into the opener and is adjustable, allowing you to set the open/close temperature.

They were super-easy to install and after testing them for a few days, I bought five more to mechanize all seven vents on the greenhouse. They’ve been in operation for a few weeks now and even without opening any windows or doors, the greenhouse has stayed at a comfortable temperature during the heat of the day. Granted, the outdoor air temperatures have only been in the upper 50’s(F).

So far, so good. It will take a couple of years of use before the final verdict can be made. That stated, I really like the quality of the Univent openers. They are made of aluminum and come with stainless steel hardware. I have seen knock-offs on Ebay for less, but from what I can see in their description, the quality is not the same. Typically they are made from galvanized steel and I have heard complaints about the push rods not lasting very long before they start leaking.

Speaking of the greenhouse, I have a lot going on right now with seed starting and I will keep this one short. I’ll be going into much greater detail on the greenhouse when I get a chance.

Watch our video on YouTube about the Univent Window Opener:

— Alan Stankevitz