Hello, all!
I am currently trying to fix up a greenhouse that is in terrible shape and I need a few ideas regarding the cooling of the greenhouse. There is a long panel at the top of the greenhouse that used to be opened with some type of motor, but I think the motor got water damaged and does not work. Supposedly, they have tried to replace the motor multiple times and it keeps dying. I need an idea where the top panel can be opened and closed on a thermostat type deal, since no one will be available in the summer to open and close it. There are other methods of ventilation, such as a fan or the side panels, however, there is worry that potential pests can get into the greenhouse. The side panel can be seen in the right of the picture and the fan is covered by the silver box in the back. If anyone can come up with an idea for the top panel to open or a way to keep pests out, I would greatly appreciate it!!

Have you looked at auto vents like Bayliss? They are very clever. There is a tube of some kind of wax that expands and contracts with temperature. That pushes a piston that opens and shuts the vent.

Lucy68 said: Have you looked at auto vents like Bayliss? They are very clever. There is a tube of some kind of wax that expands and contracts with temperature. That pushes a piston that opens and shuts the vent.

Do you know much about these? The current problem is that the panel on top is much like the one on the side, where the glass panes are all connected and need to be lifted together. Plus, this greenhouse was built in the '60s, meaning it takes some force to open it. I plan to upload some pictures of the motor that was being used later, once I get them just so there is any more ideas based on that.
I did think of using something similar to what you've mentioned, I am just very new at this and do not know much of anything about greenhouses.

We have a greenhouse forum that is active if you want to try posting this over there. You might get some answers that help more.

https://garden.org/forums/view...

Here are more pictures of what the roof looks like and the motor that was used to push the panel up.

I would place a large box fan at the doorway to pull the heat out and a smaller box ban at the other end to circulate the air. You need more vents for a GH like that.

The only issue is, there is no one that can keep track of it over the summer, so the door probably should stay shut. The person who put it together also seemed to not think about the fact that the door opens toward the direction the wind blows, meaning the wind always catches it. I'm nervous about the door potentially breaking. That's why I was wondering about a possible solution to the motor issue for the top vents to open. There is a small vent on one end and a fan on the other, but it doesn't do very much :/

OliveP, Do you have a handiman you can turn to? In the summer I would put up
a screen door and remove the glass one. Is that possible? It's just a thought.

Liv, are you planning to have plants in the GH during the summer when there is no one to "keep track of it" ?

Have you googled the company?

To revive the present system, you'd probably need a new motor (same specs). Also, a partial disassembly and lubrication of the friction spots, bearings, hinges, etc. Getting a thermostat rated for the voltage/amps of the motor and a 3-way switch would make the roof vent automatic.

Steel-framed glass is heavy, so replacing the vent panes with polycarbonate and the frames with aluminum would reduce the power needed to open the roof vents.

Looks like the side vent windows swing outward, so a screen setup on the inside might keep pests out.

I built clerestory vents that are spring-loaded. Thermal pistons open them and when the pistons cool and relax, the springs pull them shut.



There are corner vents opened by more thermal pistons, with a box of coarse screen on the outside.

karmahappytoes said: OliveP, Do you have a handiman you can turn to? In the summer I would put up
a screen door and remove the glass one. Is that possible? It's just a thought.

This greenhouse does not have someone specific that is a "handy man"… we have maintenance, but the problem with that is that they don't do much here. I've been trying to get them to fix a broken panel in the roof for weeks, but it is still to be fixed. The problem is that this greenhouse is also attached to a building, with a door leading inside, so I doubt that the head of the greenhouse would allow me to remove the outside door.

Weedwhacker said: Liv, are you planning to have plants in the GH during the summer when there is no one to "keep track of it" ?

I was planning on fixing this so that people are able to do some research in the greenhouse again. So yes, I was planning to have the cooling fixed so that people can have plants in there over the summer.

The motor that opens up the line of roof vents needs to be serviced otherwise it can sieze up. You will probably need to replace it.
With a greenhouse that size, a screen door will not really help with the cooling.
What you need to have installed by some means is what is known as a "wet wall".
You take out two or three sections of wall along the narrow ends. Replace those with a prefabricated wall section to fit exactly in the space you created by removing the two panels.
You set up a drip line on top and let water circulate down from high to low. The water should drip down through water retention padding. A pump will be required. Then by installing a very large fan outside, air is forced from the outside, threw the wet pad. Wet pads can be filled with strips of foam rubber, sphagnum moss or another suitable materials. The air flowing through the water bearing pad drops the temperature inside the greenhouse by 20-25 degrees if it is large enough.
Naturally this would be easier to install when the greenhouse was built. But it is too late for that.
You can try two large, 16" or larger oscillating fans at the long ends of the greenhouse. Have them on 24/7. Then you can mist or water down the greenhouse several times a day.

Can't get much better advice than what Chip @subarctic gave you. It needs to be done the right way. You could lessen the load with replacing with lighter framing and polycarb at that vent. That would most likely bring your motor/repair costs down and prolong the vent being able to open/close.

If you have the resources it's worth fixing the motorized vents. Combined with a thermostat they will give you the unattended cooling that you are asking for.

I agree with @subarctic that you need to refurbish the vent and motor system. From 1,500 miles away I'm guessing the motors keep failing because they are burning out trying to push open the old, likely unlubricated and maybe rusted, hinges and bearings. You might also look to see if any of the gears have been stripped or if any of the parts are bent or damaged.

In addition to fixing what you have you can also throw some shade cloth over the top of the greenhouse. It looks like there might be some on there already but if your greenhouse is too hot you might want to use a more opaque shade cloth than you have currently.