Bayliss MK7 Triple Spring Auto Vent Opener

Easy install, lots of mounting options, they work as expected except the maximum opening of 12" is a bit misleading. I originally had these cranked to the maximum opening distance, but I was in the greenhouse while it was about 50F outside and the windows were still open. So I backed off the opening setting to be closed at that position, now they are open and closed at the expected and desired temperatures, but only open about 4".
Would I prefer they still open a bit more? Yes.
If I could do it again would I still buy them? Also yes. Its only been about a month but so far they are a wonderful addition to the greenhouse (I was manually opening and closing the windows based on a remote temperature sensor with notifications to my phone)

ACF Greenhouses: I don't think you completely understand how they work. The opener is stopping a 4" because the greenhouse is not getting hot enough to cause the opener to expand further. This is common when the air outside is cooler. In warmer months, the opener will open the vent further because more cooling is needed to maintain the temperature setpoint.

The people at ACF were very helpful and reliable. I would highly recommend the Bayliss MK7 vent opener for a greenhouse. Easy to install. Set it and forget it!

I am using automated openers on wood-framed 10 ft x 2 ft side vents on a high tunnel greenhouse with the hinges on the bottom (top opening). The springs on the Univents are not strong enough to consistently close these vents, so I tried the Bayliss and they seem to be working great; much stronger springs. They open at a lower temperature than the Univents, probably about 10 degrees F lower.

Easy to install and I went with the one that had springs because I live in a windy area.

The order came very quickly and was exactly what I needed.

Put this in a small greenhouse with light weight roof panels. Works wonderfully.

Works very well in my homemade greenhouse. The closing springs are very strong.

Madam's Woman cave also known as he Orchid greenhouse needs these as the outside temperature range from 40 degrees F to 100 degrees F on the same day. They work perfectly opening and closing the vents as needed.

Well made! The holes did not align with the old ones so new ones had to be drilled to fit the new vent openers, but this is to be expected. The vents work great and if the quality is the same as the old ones that I replaced, then it will be another twenty years before I have to do it again!!! Very satisfied!!!

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.