Kitchen Garden Forum

I'm starting to think about making an automatic door opening system for the polytunnel.

I'm wondering if I can re-purpose a greenhouse vent opener such as this: http://www.amazon.co.uk/Gardman-Greenho ... o_pC_S_ttl

What's not clear to me, is if the vent opener relies on having the weight of the window for it to work. If this is the case, then I guess it would not work.

I'd be interested to know if anyone has tried something like this before / or has any alternative ideas......

Thanks

Vent openers cannot lift above a stated wright, but I think for closing they would need some weight, you could compensate with a spring to close the door, but where you could get one, apart from bungee cord?

Good point, it might need the weight for the closing, but not need it for the opening.

In that case I could probably use something like this:
http://www.amazon.co.uk/Securit-Black-A ... K5RN67YBS8

Depends how the strength of the spring translates into a moment (?), weight equivalent.