Coolbot on a Shoestring

What did you do?

We designed and built a 6 by 8 ft coolbot on a tight budget, and created a photo log of the build process. Our strategy was to fabricating an R-25 insulated box, out of 5 portable panels (minimalist…four walls and a ceiling) designed for easy disassembly/ relocation.

Why did you do it?

Johnson's Farm in Westminster had and urgent need for cold storage. Given my UVM Extension technical support role, I also needed some hands-on experience designing and building a Coolbot, and hoped to share that experience with VT veg and berry grower community. It took next-to-no effort to rope-in our Extension Ag Engineer, Chris Callahan, and we teamed-up for 2 days to whip out this 6 by 8 ft unit, and live to show and tell the tale. Johnson farm was on a tight budget, surprise surprise, so we took up the design/build challenge of minimizing cost, and photo logging our process and costs here on this Portal. We wanted this photo log to complement existing resources, specifically the info-packed Coolbot blog published by UVM's Ag Engineering program (see https://blog.uvm.edu/cwcallah/2013/03/20/coolbotstm-inexpensive-cold-storage/ ). Steroid (Coolbot's manufacturer) also has a few excellent design build photo logs on their website, ( see https://www.storeitcold.com/build-it/ ) but they are high-end, decked out, and beyond many budgets.

About how much did it cost?

$1,300--for 6 by 8 ft, 25+ R-value walk-in, including Coolbot, 12000btu AC unit, and

How did it help?

For decades, this grower has been cranking out wholesales produce (lettuce, cukes, squash, etc) on 12 acres for Hannaford Supermarket.. He as always harvested to order, and delivered immediately, skirting the mandate for cold storage. This strategy was hard work, but it did work.. But low and behold, as the decades have clicked by, Bob has not gotten any younger, our planet has not getting any cooler, nor have our weather events gotten any milder. All this has added up to a lot of stress for Bob, scrambling to receive and deliver orders every other day, in the fleeting windows between heatwaves and violent thunder storms. This Coolbot has help in several ways. It increased the produce quality and shelf-life (increasing gross sales), and decreased produce safety risks. Furthermore, and perhaps most importantly, it has increase the harvest flexibility, and decreased overall stress for Bob, which has improved the quality of his life and work.

What are you most pleased with?

Simplicity of design and materials. Increased harvest flexibility and crop quality.

Any mistakes or lessons learned?

Put your money into good insulation: 4 by 8 ft. sheets of Polyiso Rigid Foam board, is expensive, but is clearly the best R-value for the $ (compared to pink or blue-board). 2-inch is most common (about $35/sheet), and if you can find 4-inch for under $80/sheet, all the better. Start by working on pricing with your local lumberyard, and you may end up with the best pricing. We started contemplating a long trip to Lowes, but ended up saving big at the building supply just down the road. Before gluing and foaming anything, make sure everything is ready to go, cut and tested for good fit. This stuff is sticky, and tube/cans need to be all used at once. So get well-organized, pull the trigger, and finish the job. Tin, protective gloves are recommended. You really need to secure freshly glued panels with 3 inch screws and large diameter(1 ½- inch) washers Leave stud nailers exposed along the floor and ceiling of the coolbot interior. These give you a nailing board for installation of future smooth and cleanable wall surface. Install closed the door before foaming around its perimeter—We learned this lesson the hard way, after a good struggle with pry-bar and screw gun, to get the door to fit after the expanding foam had tweaked the flimsy frame.