These are the best vent openers we've used. Depending on your greenhouse design, replacement can be easy or a huge pain; plan your bench layout for access to the opener. A power tube might work for ten years or might fail much sooner; ALWAYS have a spare power tube or a spare complete opener on hand. We've replaced two power tubes on our first opener which we've been using for twelve years. Don't attempt to change the power tube without taking the opener off the greenhouse. Ask me how I know that.

The old one has functioned properly for several years. With a horrible wind it ruined the working parts. I wish I would have checked out the greenhouse further because I have partial issues on another and will need some parts for it.

It is so nice to have my window/vent open and close without me tending to it minute by minute. Great investment. I have one on my cold frame as well, and, equally work reducing.

I constructed a cold frame, using an old glass door insert. Not sure how much it weighs? But this lifts it perfectly and shuts it back down when the temperature drops.

 

Our first opener worked so well, we purchased a 2nd one--our greenhouse has two wooden gable windows on each end and we needed some additional airflow. Both of them work well. We like that they were very easy to install and can be adjusted to open sooner or later (depending upon the temperature). Initially we were a bit concerned if our windows would be too heavy for the opener, but this hasn't been an issue.