To be honest l'm not sure which would be the best @StephenSouthwest. I think it depends on the weight of the window. My greenhouse is cedar, so l'm guessing the weight would be heavier than an aluminium one.
The Bayliss website gives more information re weight bearing etc.
After a bit of adjustments it's now working well. It starts opening at about 17°C. Well impressed.
Gardener of a driveway pot garden - flowers one side, veg the other and a car in the middle. I am so looking forward to the day we can move into a house with a bigger garden.
I'm having a bit of a fiddle fitting mine - the aluminium greenhouse sill is rather non-standard! I think I'll likely have the openers in the fridge for a couple of days...
According to Dr DG Hessayon's 'The Garden DIY Expert' (and therefore probably 'The Greenhouse Expert' too) all greenhouses should have a minimum of two automatic vents, one in a wall and one in the roof. Bit of a bugger if your greenhouse didn't come with provision for a wall vent (mine didn't) but that's what is written.
My auto vent (a Thermo something I think) came with my greenhouse from the Greenhouse people. It lasted just 3yrs. But automatic ventilation is a brilliant accessory. Two well spaced vents improve air flow, helping to control both temperature and humidity.
According to Dr DG Hessayon's 'The Garden DIY Expert' (and therefore probably 'The Greenhouse Expert' too) all greenhouses should have a minimum of two automatic vents, one in a wall and one in the roof. Bit of a bugger if your greenhouse didn't come with provision for a wall vent (mine didn't) but that's what is written.
I tend to just remove the four corner glass panes around April / June time and don't replace until late September. Leaving the door open during the daylight hours is equally efficient too.
I am having trouble with the roof vent on my greenhouse which I found as a freebie on Freecycle. As far as I can work out the greenhouse is an old 10'x8' Eden. The roof vent has never had a catch so I put a length of baler twine over the outside of the window, brought it down inside the greenhouse, tied it into a circle, and put a half paving slab through it to weigh it down to keep it closed and stop the wind lifting it. During the summer I laid a length of pipe insulating foam across the window opening to keep the window propped open. That system worked well until this autumn when we had an unexpected storm and the vent window was flipped over the ridge of the greenhouse and one of the hinges was broken right through. (I had forgotten to keep the twine on the vent) The window is now lying on the roof of the greenhouse with the glass partially out of the broken frame so it means a whole new window is needed. At the moment I am unable to get up to it to sort out the mess. Fortunately, I have no plants needing protection. I have no idea if I will be able to find a replacement vent as the greenhouse is very old, made in the feet and inches era.
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I think it depends on the weight of the window.
My greenhouse is cedar, so l'm guessing the weight would be heavier than an aluminium one.
The Bayliss website gives more information re weight bearing etc.
https://www.baylissautovents.co.uk/product/mk-7-standard-autovent-unit/
https://www.baylissautovents.co.uk/product/xl-autovent/
https://www.baylissautovents.co.uk/bayliss-autovents/
Hope this helps @StephenSouthwest
But automatic ventilation is a brilliant accessory. Two well spaced vents improve air flow, helping to control both temperature and humidity.
@W@Winston_The_Gravity_Man
Just take out a pane of glass and fit one of these for a wall vent.
'The power of accurate observation .... is commonly called cynicism by those that have not got it.
George Bernard Shaw'
At the moment I am unable to get up to it to sort out the mess. Fortunately, I have no plants needing protection. I have no idea if I will be able to find a replacement vent as the greenhouse is very old, made in the feet and inches era.