Ventilation problem

[Bluemchen]

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My greenhouse (3mx3m) came with my allotment, fairly knackered, without any ventilation & I've just had it repaired. However, the panes are not standard size (24"x24"); they measure 24 1/4" by 28 1/2". We couldn't put in any automatic opening vents or louvres because they only come in standard sizes only (18"x18" or 24"x24"). There is no manufacturer's name on the greenhouse. I found a Sun Vent 100

Smart Solar Vent 100 , with FREE Delivery, Accessories

and installed that. It puports to extract 25m cubed of air per hour, so I thought that would do it, but I went down there today to find it really hot inside, and some of my lettuce wilted :-( presumably from being too hot, as it recovered after I left the door open.

How can I get some automatic ventilation installed?? Getting down there first & last thing to open and close isn't an option.

I thought about getting a perspex sheet cut to size and then getting the standard size louvre inserted in that.

Any ideas or tips most gratefully received!!

[workhorse]

What you badly need are two large roof vents, like opening a window on hinges. fitted with automatic openers. The same applies to side vents fitted lower down.

Do you have roof vents at the moment? If not is their any way of modifying the roof to fit some.

What is the greenhouse structure made of - wood or aluminium?

What ever the material; It can be modified.

[Bluemchen]

Hi workhorse,

I know I need the auto vents - it is how to go about installing them!

The greenhouse has an aluminium frame, and none of the panes have frames around them to which an quto vent could be fitted. Any ideas??

[Bluemchen]

ooh - workhorse,
I did meet aguy who leaves a top vent open permanently - what do you think?

[workhorse]

Hi Bluemchem

I think the first thing you need to do is to obtain a roof opening vent (not Lourves). This should be wide enough to span two sections of glass, or near as dam it. You would then need to remove the glass from the roof where you are going to site the roof vent. Add a cross section of aluminium to reduce the size to suite the new opener by using an aluminium infill along the side. you would then need to get glass cut to size to fill in the gap at the bottom.

Now you can fit the auto roof vent.

I know what I have said is very basic in description, but the theory is right.

You may be able to get one to the size you want from one of the greenhouse manufacturers. Its worth the try. Had a quick look around. Check this site out:
Aluminium Greenhouse Accessories

[Glasshousevirgin]

I sympathize having limited access to my GH too and it gets very warm in Summer so auto venting is a must. I was a bit phased by the installation but it worked out quite easy so if you can set one up I recommend it.
Over last Summer they worked quite well for me and I set them both to open at about 20C but still we had temps of 30C plus most days, despite using paint on the glass too, with obvious wilting and stress for plants.
This year I am going to set them for lower temps so heat build up is hopefully less and I also have a louvre in a lower pane with a vent to get some cross draught going. In addition I have curtains ready to go on the sunny side for the worst of the Summer if necessary.
Hopefully some ideas there for you in all that.