chj93

GH Vent Auto Openers

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Hi all,

I'm looking to purchase some auto openers for my greenhouse roof vents, but I would imagine that during the winter, they wouldn't open due to insufficient temperature inside the greenhouse. From a hygiene and airflow perspective during dormancy, can the openers be manually overridden? If not do you simply suffice with having only the door open in milder weather, and leave the auto openers to do whatever?

For the summer months, how easily (if at all) can they be calibrated to operate at a specified temperature?

Many thanks,

Chris.

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Hi Chris, mine will still open on "sunny" winter days which means that mostly they don't.  If you wanted to have some kind of manual override you could unscrew one end of the mechanism, the one that connects to greenhouse I'd think, and then rig up some means of propping it open.  Air flow is more of a problem for me in my cactus/succulent greenhouse than in my CP gh and of course those plants mostly won't stand it being too cold so I have fans going 24/7 365 days a year, doors/vents closed and the whole thing insulated with twin wall polycarbonate. For my CPs I might occasionally open the door and windows on sunny winter days but mostly I don't bother.  How important this is for you probably depends on a number of things like what you're growing, how much direct sunlight the gh gets etc .

Adjustment in summer is a trial and error affair, you could play about to get them opening more or less exactly when you want I suppose but it's not something I ever got too hung up about.

I'm sure other members will chip in with their experience.

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I have A elite greenhouse with two roof auto vents if you want to open them manually

you just push them up and put a support in easy 

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I don't use auto openers as I'm always worried about strong winds catching wide open windows and causing some serious damage. Opening the door is rarely sufficient, even in winter, you really need some forced ventilation i.e. fans to circulate the air to keep mould at bay

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Hi 

 manufacturers tell you to dismantle  the cylinder from the  greenhouse auto vents  in the winter time as the low temperature damage the solar  part of the  cylinder 

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21 minutes ago, nev3970 said:

Hi 

 manufacturers tell you to dismantle  the cylinder from the  greenhouse auto vents  in the winter time as the low temperature damage the solar  part of the  cylinder 

I'm using Bayliss Mk7 autovents and they specifically say on their website FAQs that it is not necessary to remove the cylinders for winter.

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32 minutes ago, nev3970 said:

manufacturers tell you to dismantle  the cylinder from the  greenhouse auto vents  in the winter time as the low temperature damage the solar  part of the  cylinder 

I've never heard of this before so I've never dismantled mine. One of my greenhouses is 5 years old and so far it hasn't been a problem.  Maybe in the long term it could be a concern but I think I'll leave mine connected all the same.

I found this on Bayliss website in answer to a question about auto vent suitability in areas where freezing conditions are experienced (the question asked was are they suitable).....

A: Yes. There is no evidence to suggest that low temperatures would damage the tube. We can experience temperatures as low as -15 degrees Celcuis (5 degrees Fahrenheit) here in the UK, and the autovent units on our own greenhouse have not experienced any problems.  See here

Maybe different manufacturers advise differently, do you have any links to the manufacturers recommending dismantling?

Edited by Gaz
amend text

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Bayliss uses wax tubes whereas other folks use gas filled tubes, this might make a difference to how well they cope with low temperatures.

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