Automatic Greenhouse Windows

[General Woundwort]

In the greenhouse which I've discussed on this forum, I am baffling over how the automatic windows work. No apparent wires, just hinged windows which open and close depending on the temperature.

I only can assume this is similar to the bi-metallic strips with the off-switch in electric kettles. Would this be correct?

[pdblake]

I think it's more like a piston. It looks like a gas filled tube (mine does anyway) where the gas expands in the heat and then contracts again, pushing and pulling the window.

[Snadger]

Shame the whole roof of the greenhouse can't be made to open once it starts raining.
I must admit to feeling a bit of a prat this evening with a watering can in my hand in the greenhouse.........waiting for the rain to subside so I could venture out to fill my watering can again!

[Capsid]

There is a wax solution which expands and contracts as it heats up and cools down which moves the piston in and out.

[Snadger]

There is a wax solution which expands and contracts as it heats up and cools down which moves the piston in and out.

Like a wax pellet car thermostat I imagine!

[Bigmallly]

Mine is the same principle as above but under tension with springs so the window always wants to close if that makes sense.

[General Woundwort]

Great, thanks.

[salilah]

My challenge (as yet unresolved) is that the auto openers on the roof vents work fine - but the auto openers on the side vents don't work at all, in that they have forced the link to the vents to break / come off, i.e. they can't close
Need to follow up with the greenhouse folks I guess
S