AC in GH

We have a 8' X 12' GH with 2 roof vents. We just started our portable Honeywell AC but with the door closed and the roof vents wide open the temp went over 100. I opened the door and it dropped to 97. Should we keep the roof vent closed? Also. the exhausted fan is controlled by a thermostat . Should that be allowed to run?

I use Aluminet, a woven aluminum reflective covering, on my greenhouse from late March through September with one exhaust fan and replace the two solid doors with screen doors. No roof vents or AC. My greenhouse stays approximately ten degrees cooler than outside temperatures with the Aluminet. At the end of the hot weather it gets stored. Now eight years old, it's a terrific product! You can buy it pre-sized with finished edges and grommets. It was more cost effective for me to buy yardage. My greenhouse is about twice the size of yours.

We got a screen from Greenhouse Mega Store, it seems help a little bit but not a whole lot. We live in SW Mo. Hot & humid!

Well, they don't call it Hotlanta for nothing. Hot and humid as well. I don't understand what you mean by "a screen". Is it shadecloth? What is the material? What is the percentage of screening? Again, Aluminet is a reflective material and therefore much more effective in keeping heat out while allowing diffused light in. I used to use regular shadecloth. Aluminet is a superior product. It is considerably more expensive than other shadecloth products but less expensive than running AC. I can't imagine needing AC in a greenhouse unless you are growing high elevation plants. Then I'd recommend a swamp cooler system.

Edited to say fans should run continously for health plants.

This message was edited Jul 31, 2020 3:19 PM

I am resigned to a 100 degree greenhouse. I do have a 100 gallon stock tank in it with a pump running and some moss growing on the tray, and a vine right now. If I would get my winter insulation rolled up, which I might this coming weekend, I can probably get down to 90, because ventilation will improve. I'm in north Texas, it's just used for 3 or 4 months in winter. I had to go to solid roofing after hail took out the transparent roofing 2 years running, and that does provide more shade, below the solid corrugated I hung 1 inch light colored styrofoam, to reflect light back into the greenhouse and provide some insulation, there's about 5 inches between roof top and the top of the styrofoam right now. I'm not trying to air condition it, that's for sure

I am not a prominent expert in those kinds of things, but I can suggest some ideas. Firstly you have to disconnect the fan from the thermostat because at the moment it is just a waste of electricity. About the room temperature, you should think about a temperature that will satisfy you. Suppose you want something colder open both the roof vents and the door. In case you want something hotter, then keep the ducts and the door closed. Either way, you should call some workers specialized in this field, to give you advice.

This message was edited Sep 4, 2021 4:09 AM

That Aluminet sounds pretty cool, but I just empty my greenhouse in April and leave it that way til just before first frost

I empty out most everything in Spring, which is orchids, but like to do cuttings and seeds for fall, throughout summer, while the orchids spend summer under a pergola. Without the Aluminet it is intolerable. Orchids require constant circulating air and high humidity so fans are running 24/7 regardless of temperature and even when solid doors are replaced with screen ones.

Maybe when I retire! Sounds wonderful

I think you’d better consult a professional on this one. Preferably, someone who knows aircons from A to Z, overhaul to chemical wash , I should say. I mean, we’re all amateurs here and the question you have about the aircon is pretty serious. Where I'm from, the weather is super hot and humid, we keep the vents pretty much closed most of the time. I guess it’s also predicated on what kind of plants we’re talking about. Different strokes for different greens and all.

This message was edited Oct 8, 2021 5:09 PM

This message was edited Oct 8, 2021 5:11 PM