I have some pic's of our window assembly at link below. Clips definitely go on the outside. I did two windows on each side of the roof. Could putting all four on the same side be part of the problem? Regardless, my windows don't fit together very well either but they do close. Now that I have the vent system in I don't think I'll be opening them again. I may even wire them down to prevent opening.

Here is a link that might be useful: Window pics

Troykd,
Thanks for the response. I looked at your pictures--and any others I could find--before posting my entry on the forum. I have taken the windows apart and re-buiilt them a few times, and it seems there is only one possible way to assemble them so they look right. But this leaves absolutely no room for clips on the outside. There is a space on the inside, which is created by inserting the the bolt heads for the handle and side connections on part #40, and #38 at the top. The polycarb is firmly in the channels on the top #38 and sides #39. Can it be that I have a revised set of parts?
The first two vents fit properly. The second two will close with a sharp pull, but do not fall into place automatically--they seem to be binding against the roof frame piece. Maybe this is the best I should expect.

You don't indicate where you live but if it gets above 80F the vents will not cool it anyway.
Also with working vents that causes a problem for putting on a shade cloth or thermal blanket for cold weather.
I have a thick Magni-Clear thermal blanket over the entire roof and it is bolted down and left their year round.
On the inside I have the bubble insulation over the entire roof and side walls.
For less $$$$$ than what the vent openers cost I installed a 16" exhaust fan and if it gets too hot the fan comes on and cools it.
With it sealed air tight and insulated good I save way more in electric bill for heating than what it cost to run the fan.
My advice would be forget about the roof vent and buy a good fan you will need it even if you use the vents but the exhaust fan Will not work with the vents open so the vents will only be of use when it is really cool outside.
I got some windows at a surpluss for $20.00 and installed them in the back.
Most days we have a brezze and I can open the door and the windows and it will stay cool so I only depend on the fan for when I'm not at home since some times when I leave it is too cool to open the greenhouse up.
I just leave and the thermostat and fan will take care of it until I return home.

Here is a link that might be useful: Photos of HFGH

Gardenerwantabe (I think I finally spelled that right),
I have read many of your posts, and it seems your current system was the result of an evolution regarding the vents. I am in coastal So. Cal, where it gets quite warm in the summer. We don't get frost in the winter, but it does get cold. I just bought an Aluminet shade cloth from the manufacturer. They claim it will not unravel if cut, and I plan to cut an outline of 4 vents wide and long, roll it up and secure it to the crown or base of the crown. This will leave a hole on the vent (leeward)side, but it is sheltered and I think I can keep the cloth on tightly.
Ideally, I would like to arrange it so that I can go away for over a week and have the place take care of itself. Maybe this is not possible.
I have considered your ventillation system, but am not yet ready to give up on the vents altogether; perhaps like you, I will get to that point after I see how things work out. I do appreciate your input.
Why won't the exhaust fan work with the vents open? Does it work with the windows open, or is that just another option you have when you are available to use and monitor it manually?

Ann

Why won't the exhaust fan work with the vents open? Does it work with the windows open, or is that just another option you have when you are available to use and monitor it manually?

With the vents open the exhaust fan will pull air in them and not be nearly as efficient as pulling through from the front lower part of the GH.
I'm retired so I'm home most of the time and the windows require monitoring if it is cool.
I have wireless thermometer in the house so it is easy to watch the temp.
What works best depends on where you live that is why I mentioned it.
Also depends on if you are going to use it year round.
I live in northern Indiana and only use the GH to start plants in the spring. I heat it Jan. Feb. then heat at night and cool in the day time March and April. After that it will sit empty till the following Jan.
What is best for one may not be what works for someone else.
Where I live the vents are just not worth the hassle and I can leave my thermal blanket on with the roof sealed air tight.

I finally got the 4 vents to fit properly. There was no specific problem--only after unbolting each one in place in the roof could I maneouver it into a position which enables them to close MOST of the time. It has been a very time and patience-consuming ordeal.
Next step is to install the shade cloth.
Thank you for your advice; I will be thinking about the best thing for my situation.
Ann