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Oh my!!! It is only 80°F today and inside my home made green house WITH the door and window open with a fan on high is 96° In there.

This is for my seedlings mainly only. To keep 50% of the sun off then and any rain showers.

Question? I am going to add another door in the opposite side where the orange circle is. You think I will need to do that also on the sides? Where I live in NC the summer temperatures average between 85 and 90° Again today it was only 80° And I’ve been frantic Trying to cool this greenhouse down.

WOW!!! Quite a learning curve for me.

Just removed some of the sides and allow wind to blow in throughout the day. I have multiple windows open in my greenhouse, and up here it is just 10C even.

Aiko wrote: ↑Fri Mar 24, 2023 6:48 pm Just removed some of the sides and allow wind to blow in throughout the day. I have multiple windows open in my greenhouse, and up here it is just 10C even.

I agree with Aiko in principle. Joe -- if you have doors on both ends of your greenhouse, it'll get much better air flow when you keep them open. Also, your fan is blowing air in the wrong direction. If you turn it around, it'll be an exhaust fan which exhausts hot air out of the greenhouse. Not as effective as a "squirrel cage" fan, but should help a little bit.

Heat rises. You need to vent the heat towards the top. Blowing cooler air in low will not help cool things down.

mikethecactusguy wrote: ↑Sat Mar 25, 2023 7:48 pm Heat rises. You need to vent the heat towards the top. Blowing cooler air in low will not help cool things down.

Good point. Though the plants are down low, it would still be more effective to expel the hot air near the roof.

Maybe attach a board or a couple to 2x2s to the door frame tubing with screws or u-bolts and mount an exhaust fan to that.

Steve Johnson wrote: ↑Sat Mar 25, 2023 2:18 am

Aiko wrote: ↑Fri Mar 24, 2023 6:48 pm Just removed some of the sides and allow wind to blow in throughout the day. I have multiple windows open in my greenhouse, and up here it is just 10C even.

I agree with Aiko in principle. Joe -- if you have doors on both ends of your greenhouse, it'll get much better air flow when you keep them open. Also, your fan is blowing air in the wrong direction. If you turn it around, it'll be an exhaust fan which exhausts hot air out of the greenhouse. Not as effective as a "squirrel cage" fan, but should help a little bit.

Ok Steve I was wondering about the fans Direction I’ve got four thermometers inside greenhouse to get things perfect.

greenknight wrote: ↑Sun Mar 26, 2023 1:29 am

mikethecactusguy wrote: ↑Sat Mar 25, 2023 7:48 pm Heat rises. You need to vent the heat towards the top. Blowing cooler air in low will not help cool things down.

Good point. Though the plants are down low, it would still be more effective to expel the hot air near the roof.

Maybe attach a board or a couple to 2x2s to the door frame tubing with screws or u-bolts and mount an exhaust fan to that.

Working on it now. THANK you

mikethecactusguy wrote: ↑Sat Mar 25, 2023 7:48 pm Heat rises. You need to vent the heat towards the top. Blowing cooler air in low will not help cool things down.

Sounds worthwhile to me. I will do it today. THANK YOU very much

If you have at least one hole / window in a opposite wall or roof it will be enough to get air to move. Fresh air will constantly come through the door and hot will pass away from window.

Fresh air will constantly come through the door and hot will pass away from window."

Yes cross flow of air . When I grew cactus in Phoenix AZ the entire city was a greenhouse at 115F. Some types of cactus can take extreme heat and some don't like it. Better at 90F I would think ? A cool day in a Phoenix Summer. I used to freeze water bottles and use the ice to cool down the tap water in a bucket before watering my cactus with it. During a monsoon the rain was never hot .

keith wrote: ↑Mon Mar 27, 2023 8:57 pm Fresh air will constantly come through the door and hot will pass away from window."

Yes cross flow of air . When I grew cactus in Phoenix AZ the entire city was a greenhouse at 115F. Some types of cactus can take extreme heat and some don't like it. Better at 90F I would think ? A cool day in a Phoenix Summer. I used to freeze water bottles and use the ice to cool down the tap water in a bucket before watering my cactus with it. During a monsoon the rain was never hot .

WOW Keith!!!! What a story!!!! Even the name “Phoenix” sounds hot!!!

JCcares wrote: ↑Mon Mar 27, 2023 7:08 pm

Steve Johnson wrote: ↑Sat Mar 25, 2023 2:18 am

Aiko wrote: ↑Fri Mar 24, 2023 6:48 pm Just removed some of the sides and allow wind to blow in throughout the day. I have multiple windows open in my greenhouse, and up here it is just 10C even.

I agree with Aiko in principle. Joe -- if you have doors on both ends of your greenhouse, it'll get much better air flow when you keep them open. Also, your fan is blowing air in the wrong direction. If you turn it around, it'll be an exhaust fan which exhausts hot air out of the greenhouse. Not as effective as a "squirrel cage" fan, but should help a little bit.

Ok Steve I was wondering about the fans Direction I’ve got four thermometers inside greenhouse to get things perfect.

So Steve I just wanted to give you an update a conclusion on this thread. After it’s all been said and done at least with this particular handmade greenhouse 10f X 8f.

Steve when I point the fan up to the ceiling it blows all the hot air out that window on the back door and keeps the greenhouse a perfect controlled temperature. At least for this greenhouse that’s how it’s working. When the 90f heat comes in the Summer like a carpet I’m going to roll up the sides to get some more ventilation.

Looks like you have it nailed, Joe! Good job!