Greener Thumb
Posts: 772
Joined: Wed Nov 28, 2012 5:00 pm
Location: Virginia, The mountains Zone 6a/6b

Managing heat in a small greenhouse

Hello all. After building a really quick and cheap hoop house last fall, I've been contemplating buying or building a small greenhouse. I do have a few concerns. I can't figure out how I could possibly manage the heat without some sort of sophisticated (and therefore expensive) automated system.

Here's my problem. We have a small greenhouse here at work...one very much like the one I would want for home. But during the day the temps get WAY to high in there. Yesterday afternoon the outside temps were in the mid 60's, and the temps shot over 120 with the vent panel on top open to the widest setting (its a roughly 2 foot by 2 foot panel hinged on one side and vented open about 4 inches on the other. It's no big deal here at work because I can run down every hour or so and open and close the door and vent to regulate temp. But I can't leave plants in there over the weekend, and I certainly couldn't use this set-up at home.

At home, most days I leave before dark and don't return until 5 or 6 o'clock in the evening. There would be plenty of days where if I open it up in the morning before I leave, I could kill the plants because of the cold and yet if I leave it closed up things would bake to death in the afternoon.

So, how does one manage that?

Thanks for any ideas!

Green Thumb
Posts: 373
Joined: Sun Mar 16, 2014 8:46 pm
Location: Noblesville, IN Zone 5

Re: Managing heat in a small greenhouse

I have my GH attached to the house with a window fan circulating air between them to balance temps. It also can be opened on both ends for cross flow. I have been trying to come up with automated system as well. I am leaning towards a gable large attic fan for the roof with a diy hood from polycarb/sheet metal blowing out and another on the shady side with hood blowing in. They 60 to 80 bucks at the big box stores that have adjustable thermostats included to turn them on. There are some solar motorized roof vents but not quite there in technology/price yet IMO.

Hoop house can have a roll up bottom. It could be diy with a motor similar to automatic awning on a temp actuator. Gas/temp actuators are expensive and I would pay 40 bucks if I only need a couple but that wouldn't cut it. If you rigged it up to a multiple awning window it might work. Like trailer windows and take off the cranking parts.

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