[GpsFrontier]

Hi fintuckyfarms,

So the misters are in the ground in the sub T system? I am assuming they help cool the air sort of like the swamp cooler.

Their inline with the hot air inlet tube, but able to be accessed for any maintenance like changing clogged mister heads. The misters aren't part of sub "T" designers plan, but a modification on my part. If you have ever stood in front of fan that sprayed mist (like at lots of sporting events), you for sure know how much cooler it is. Basically I put them In the sub "T" system as a sort of pre cooling system. We have extreme heat here, and because of space issues, the sub "T" system Is smaller than I originally wanted. The sub "T" designer has never tested it in 120+ temps (that I know of), but more like 100-105 temps. The theory is that the higher temps running through it here in the desert may lead to higher ground temps than it's been tested/used in so far. Increased ground temps would reduce the temperature differential, thus cooling effect that could be accomplished.

Example: take two glasses of cool water and stick one outside on a real hot day, and leave one inside at room temp. The one outside will have a lot more condensation form on the outside of the glass than the one inside. That's because the temperature difference between the air temp and water temp outside is grater than that inside (temperature differential). The goal of the sub "T" system is to have the hot humid air/moisture condense in the tubes.

Now with that in mind, say the normal moist ground temp at that depth is 65 degrees, and to function well you need at least 10 degrees of temperature differential. The coolest the air coming out can reach is 75 degrees. pump extreme hot air through it, and that could cause the ground temp to rise depending on how your system is designed (tubing spacing etc). If the ground temp rises from 65 to 70, the coolest air temp it could reach would be 80 degrees. For maximum efficiency a temperature differential of 20-30 degrees is best. In other words, with a ground temp of 65, that suggests it should work most efficient when the air going into it is around 85-95.

Because this type of system has never been tested in the desert heat, and under our extreme conditions. Not to mention ever been tested with cooling misters installed. It leaves me with more than a few theory's. One is that the misters may backfire cooling the air to much, reducing the temperature differential so much before it reaches the underground cooling tubes that it wont' condense. On the other hand, running the misters off and on may be able to keep the ground temps from rising, thus maximizing the temperature differential. Another theory I have, and think is most likely is that the drastic temperature change from the hot air coming in and when the air hits the cool mist will likely cause instant cooling and the slower air speeds through all the smaller tubes will absorb the excess moisture. But trial and error will tell.

I can't say for sure the misters will help once the greenhouse is running and full of humidity. But they sure helped cool the exhaust air to 78-79 degrees this last summer when I got them running. I can shut the misters off or run them one at a time. From there I will be able to test air temps to see if it's helping. Excess moisture goes directly in the ground, and the mister heads use 1 gal per hour ea. You can see that running 2-4 mister heads 24/7 would not be economical or water efficient. One mister head in each system (2 total) would use about 1,500 gallons a month. However I expect to only use them during the hottest parts of the day, and or only on the hottest days, maybe even only in one system at a time. But the key is testing to see how it works, and how to improve it if possible etc.. It was a cheep modification, and I don't even need to turn them on if they aren't giving any benefits.

So how do you plan to heat the greenhouse?

The most efficient option in my opinion so far is using a Catalytic Heater. Something like this: Coleman BlackCat PerfecTemp Catalytic Heater. But instead of using the small propane tanks, adapting the larger 3-5 gallon BBQ tank. The downside is that it dosen't have an automatic temperature control. So I will need to manually run it, and set it low enough it wont overheat the greenhouse while I sleep. That probably wont be a big issue because I likely wont need a heater during the day, and I rarely get to sleep before 4-5 am. So I'll probably just get it nice and warm before I go to sleep, then shut it off.

Has anybody used the greenhouses that Costco carries? I have been looking at the 4K one made by Sun something.

Do you have a link? We don't have a Costco in lake havasu.

Has anybody gone "off grid" with their greenhouse? If so what methods do you heat/cool?

There are methods like passive heating and cooling. And I have seen people using solar/wind/and/or geothermal energy. It of coarse depends on your location and needs. I plan to use those methods myself once I'm able to grow the business and expand into larger greenhouses. In fact the sub "T" system is a form of geothermal energy. It uses electricity, but will only take a relatively small solar panel to run the fans.

P.S.
Hope you have a happy birthday.