Quick question for all of you.

I've inherited a neglected 10000 sq ft greenhouse. Basic systems which means although I've got good airflow it's not exactly cool.

We have a 30x11x5 foot tank under a Quonset style roof for shade.

Here's the question - has anyone tried pumping/spraying water over the roof to cool it? Water will be returned from the gutters to the "cooling pond".

Theoretically it will work to some point. Just curious if anyone has any experience with this?

Thanks

Lucky you! I'd kill for a greenhouse that size! I have no idea whether it would work or not. It should work to some degree. Where are you located? What do you plan to grow? If your area isn't humid, you could just install a large swamp cooler for it.

Growing Swiss chard (4 types), 3 of kale, and 5 of lettuce.

I'm on Cape Cod, Ma
Problem is I'm doing it 6 shelves high so I've got a little over 1200 lights

It looks wonderful! Enjoy the heck out of that wonderful greenhouse. Do you sell your salad materials?

We sure do. It's a struggle as you all know - but I love it!

I'm going back and forth trying to decide if this will work...

Let me call @MoonShadows. He may have some ideas for you.

I don't have any experience with a system like you describe, but I doubt it will work. Your issue is the big mass of hot air inside the greenhouse. Cooling the roof won't efficiently cool the air. Also what are you going to do with all the hot water you generate? You can't recycle it to the roof, it'll be too hot. I think you have to deal with moving and cooling the air and that means fans and other air handling equipment.

Do you have shade cloth up?

Hi @Howie74 and to the group.

I tend to agree with @Henderman. It's not a hot roof that is creating heat in the greenhouse; it is the sun passing through the skin of the greenhouse, warming the plants, fixtures, flooring materials, air, etc. and becoming trapped inside the greenhouse that is creating the heat. Spraying the roof with water will only decrease the amount of trapped heat insofar as it's ability to reduce/deflect the amount of sunlight passing through the roof, which will be just about negligible. You would be much better off concentrating on shading and air movement systems.

Thanks so much for all the good info guys.

As far as cooling after I pull the heat out of the roof I have a 30' x 11' x 4' deep pond under a Quansett style roof there's about 8000 gallons in it.

My main investor feels really strongly about getting this going so he's made some good resources available.

We've got a couple of rolls of panda paper in that stuff does work very well. It is only in a limited area. With all those lights with the white side of the paper up against the inside layer of greenhouse plastic I seem to get a very hot layer at the top. Makes sense I guess the energy has to travel through the two layers of the greenhouse roof, then back out.

I did get a little present of six 21,600 ft.³ per minute fans. It turns over the air very very quickly - But it IS certainly a thermal mass issue like you said.

So I did a test yesterday. It worked but not nearly as well as I hoped. It only saves me about 5°.

I'll update you all later - but "The struggles of a poached farmer" continue.

This is what got dropped on me for conditions! Some stuff to work with but no protection from above let's see what we can do today...

I'm not quite sure that such an area would be enough. If we're talking about replacing the new gutters on the roof, it costs a lot more than you mentioned. If you need help with that, I can advise you at https://tdhomepro.com/. The specialists at this company have replaced all the necessary parts and materials at a lower price. I was surprised at this situation, but it turned out to be accurate, seriously. If you are looking for professionalism and experience in this field, then I can advise you this same chance.