Greenhouse Cooling

[1greenearth]

Here in florida, my greenhouse is already too hot.
Is it a bad idea to use an AC unit instead of an evaporative cooler? I guess maybe an AC unit could dry up the air. But here in FL humidity is not in short supply.

Thanks,
Tom

[cowboy51278]

i haven't built my greenhouse yet but in all the reading that ive been doing and owners ive been talking two they all keep telling me the same three things that are keep to greenhouse cooling.
1- have the peak high enough.....one guy suggeseted never under 12'
2- put in a big exhaust fan and, depending on the size of the greenhouse, at least two intake vents. one guy had actually planted 3' high shrubs next to the wall where the intake vents were so they were drawing in cool air from under the shrubs.
3-one guys has an old freezer that he has rigged up so it automatically fills with water and has a pump with a timer. it kicks on a few times in the afternoon and mists the greenhouse under the benches so the plants dont get a shot of cold water but its effective in cooling the air. he said that he had tried an ac unit but with electricity it was cheaper to run the freezer with the top open than it was the ac unit and far more effective.

hope that helps i know the first two are a bit more of an "as you build" kinda thing, but maybe the cold air mist idea would work. good luck.

[Ross]

AC unit wouldn't be bad, just really expensive to run. Why don't you want to run an evaporative unit (swamp cooler)? They are cheaper to run and keep the hunidity higher. And did I say cheaper to run?

[AHAB]

Why not a wet wall?
AHAB

[Randy]

Howdy,

I have a completely different suggestion. Would you be able to install a geothermal system for cooling? It might be a bit expensive to install (mine cost $7,500) but you could cool your house and your greenhouse for next to nothing. The water comes out of the ground at a constant temperature close to 52 degrees F. It works better with a 2 well system than a single well with a loop because the loop is close to the surface and would get too warm. With the 2 well system the water temperature stays nice and cool.

I heat and cool my house with the system. Currently I have only gone through the heating season with mine where it would be less efficient for me in NJ. It worked great. In the cooling season it will be even more efficient. When my greenhouse is finished I am going to connect a separate thermostat to it and get heat and possibly extra cooling from the geothermal system.

In the long run the geothermal system will save you $$ for the electric it would cost to run a conventional AC unit. The only electric it uses are some fans to pass air over the coil and blow it into the house/greenhouse. Ceiling fans definitely help pass the air around. I only paid for electricity this winter, half of which came from my solar panals (which face East not South because my roof faces East) so my total heat/electric bill for January was $125, February $90, March $65,

Randy

[AHAB]

Geothermal sounds great!
Here in Florida the ground water is around 72-73 degrees from what I have read... that would still be a great idea.
What made up most of the $7,500 cost?
AHAB

[1greenearth]

the wet wall is definitely a great way to go! But. . .this is a commercial GH with doors on both ends. This enables awalk way through the GH into the sales office. As my nursery is 2 acres w/ most of my sales generating (at present) from standard nursery trees/ foliage. While my passion is orchids (has been for almost a decade) it is not yet able to pay the bills. hopefully this will change someday as more people realize the quality of my grown orchids in the area.
Being a new nursery is an enormous challenge. Not recommended for anyone unwilling to work around the clock! the wet wall will be installed in the next GH. My GH now is an 18'w X 36' (film on the long sides) Any how thanks for all the insight. I have found 'complete' wet walls for sale through several Grenhouse supply comps. such as GHmegastore, stuppys, and others. all are very reasonably priced.
thanks, tom (green earth nursery)

[Randy]

Originally Posted by AHAB

Geothermal sounds great!
Here in Florida the ground water is around 72-73 degrees from what I have read... that would still be a great idea.
What made up most of the $7,500 cost?
AHAB

The $7,500 cost came from a myriad of things, like digging 2 deep wells. BTW, that's where the water will be 52 degress. Once you get to a certain depth everything is the same temperature almost everywhere on the Earth; except where it's frozen all the time. Certainly, everywhere in the USA. There is some heating of the air involved here in NJ; fans; coils for the water; the duct work; the piping for the water to flow from well one, through the house and to well 2; thermostatic control; pumps; and other stuff I'm sure I can't even think of.

[AHAB]

Hey Randy,
Very cool... !
Where can I find more info about this type of system?
Thanks,
AHAB

[Randy]

Since you are in a geographically different location from me I can't recommend a contractor. Why don't you do a google search for your specific area? Then have someone come out to your home and tell you about how you could install such a system in your area.

Randy