In my experience, it's easier to mount vent openers when the frame is completed. I think pre-drilling and having to make sure the position of the holes is exactly right is making it too difficult on yourself.

Kudzu9, Thanks for the response. I've still been trying to contact Superior Autovents, with no reply except to say they will get back to me sometime...
The framing is complete. I am beginning to install the panels, and wanted to make sure the vents (which are all on the same side) are going to fit properly. It's just the vent windows which need drilling, plus part #42 at the bottom of the vent. It seems to be much easier to install the vent opener now, when I can take the window apart and drill the holes, than later, when I would have to pull the roof apart and take all the vents off to drill the parts and then replace them. There are only 2 windows with the vent openers. Anyway, I think if I buy some angle aluminum and cut and drill it to fit (the piece supplied by the manufacturer is just not the right size), I can make it work.
Did you install these openers with no problems? It just doesn't seem to fit properly. I was hoping to hear from someone with experience in this particular area.
Ann

gardnergal-
I have an aluminum greenhouse that's not a hfgh, but similar. Therefore, I can't offer you precise guidance. It's just that I've been a tinkerer for 40 years and it was my experience rather than my specific knowledge talking. The Bayliss is a very nice opener; when you say that it "just doesn't seem to fit properly," what part doesn't look right to you? The mounting to the frame, or the mounting to the vent, or what?

kudzu9,
The sample diagrams portray the top arm (attached to the vent window framework) being mounted 90 degrees from the orientation of the bracket which attaches the lower arm (which is attached to what they call the "sill". On my configuration, there is no real sill to speak of; just a flat bar which is screwed to the framing, and provides a ledge for the vent to close into. There is no way I can see to physically attach the aluminum "L" bracket they provide to this piece; the opener is too large. I think when I finally get to talk to them, they may say I just need to buy a longer L bracket to get the clearance for a
proper fit. I appreciate your offer to try to figure this out; I have been unable to install the product with the hardware they supply. If this is not clear, let me know and I will try to post a picture or be more specific. Thank you,
Ann

I'm only guessing here, but, from your description, it sounds like you may have to fabricate an accessory bracket that you can attach to the sill, and then attach their bracket to that. I don't know what your skills are or what tools you have. You would need a piece of aluminum angle bracket (Lowe's or Home Depot), a hack saw, a power drill, some short stainless steel bolts, and a tap to thread holes in the bracket. It may sound daunting, but it wouldn't be much work if you're handy, or have a handy friend. Good luck.

Yes, I was thinking of omitting their bracket altogether and drilling holes in a section of aluminum "L", with a longer side, and substituting that. They are still not answering the phones, and I have now waited a week for customer service.
Thanks for the advice!
Ann

For anyone reading this later, who is trying to install the Bayliss MK7 vent opener in a HFGH, I offer these comments. I did as I planned in the above post, and fabricated a substitute bracket. But upon mounting the opener to the "sill" (part #42), I find that Part #42 is too flimsy to hold the opener in the correct position. The opener's weight makes it sag down below the vent!
The only way I can think of to support the weight is to mount a heavy aluminm L bracket which is almost the full length of Part #42, directly onto Part #42. I will post a solution if I find a workable one.

gardnergal-
I think the idea of reinforcing the flimsy part with a full width piece of aluminum angle should work. Hopefully you can then get on to enjoying your greenhouse! Good luck.

Yes, I was successful, but the aluminum angle (1/8th thick) needs to be the full length of part #42, and screw into the framing along with #42....this means one needs a longer bolt which has already been inserted in the framing to attach the greater width of materials. Got my DH to grind some T bolts for me, since I didn't relish taking the framing apart to re-do the bolt configuration at this late stage. It is now quite solid, and seems to support the weight of the opener well.
I am surprised no one else from the HFGH club has commented on this--can I be the first to install the Bayliss openers??? Anyway, I am glad to contribute a small note in the Improvements Department.
Ann

gardnergal-
Congratulations...you are persistent!