Adding ventilation to the greenhouse

Last year was my first experience with a greenhouse, I found out how hot it could get and really needed to do something about that. Ventilation is the most important part of keeping a greenhouse a habitable temperature for plants from what I have read. And it seems the greenhouse I bought has very little air flow. With just a single 12" fan and a screened door the temperatures would get well into the 100s F quite often. I need to keep the temps in the 80s-90s F so lots of changes are needed to get it working.

I bought some louvered vents that I will install on the sides of the greenhouse to pull in fresh air. And I also purchased a 14" fan to add more air flow. With two fans pulling out air and two vents allowing fresh air to enter I hope it really helps to lower the temperatures.

Using some tube steel I build a frame for the fan and vents to attach to. Since the greenhouse is made of plastic sheeting I cannot attach much to it. So I must build out any framing I need.

I cannot use wood in the greenhouse, unless I painted it really good. But I just decided to go with what the greenhouse was already built out of and used it.

The supports for the fan required me to cut two vertical beams at a 15 degree angle.

I fastened them to the existing beams using L brackets and self tapping screws.

These L brackets are quite versatile, I also got some flat plates I will use to join other beams.

Since the upper part of where the beams attach is at an angle, those L brackets would not work well unless I bent them really good. My vice is not up and running yet so I just decided to use my flat plates to join them.

Using an index mark I made sure everything lined up to give a tight fit for the fan I am installing.

Next I cut out the plastic wall using a multitool.

With the plastic removed the fan can now function once it gets power. I need to fill in those little gaps in the sides with something, another project but for now its installed and I do not need to worry about bugs moving in during the middle of the winter.

I will wire it up to be controlled by a temperature sensor and both fans will hopefully pull enough air through to help.

Next up is to install the passive air vents, I will put two of these in on both sides of the greenhouse.

Framing it all up its ready to be fastened, I will use the flat plates to join the metal beams. If I could weld this would be a good way to join them too, need to get my workshop fully powered before I can do that though. Also need to learn how to weld.. lol

Using L brackets I attach the frame I made to the bottom of the greenhouse structure. I may follow up and add two more brackets on the inside as well. But for now it feels quite strong.

With the vent installed I can see when I turn on one fan it makes the louvers raise pulling air through. Looking forward to seeing how well they open when both fans are going. Just need to get it all wired up.

So what’s next?

I am working on getting water ran from my well pump to my greenhouse. Supplying the misters with enough water I would need an array of barrels, or a constant source like from my well. Hopefully this will be done by spring, so I can have misting along with good ventilation. Between a good mist and air flow I hope the greenhouse is all dialed in and can be a great resource to grow plants and seedlings.

My current move in date for plants is around late April, I hope the risk of frost should be over by then. And at that point many things can be raised in the greenhouse, and then transplanted out into the raised beds for growing fruit and vegetables. I would also like to grow cannabis in the greenhouse, though I really need to get the temperature and humidity dialed in to do that. Otherwise I will just grow them outside the greenhouse in the Spring.

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