Refrigerated Trailer for Vegetables
Kent Coates, Nature’s Route Farm
Cold and food safe transport at the market scale is a challenge we need to overcome to ensure both food safety and quality of farm fresh products sold at markets. The following ideas are a summary of Nature’s Route Farm’s experience.
Off the shelf or customized cooling trailers and trucks are very expensive. Quotes we have heard for complete systems range from $12,000 to $20,000 for the insulation and refrigeration systems, excluding the cost of the vehicle. Not including my labour, we paid less than $4000 for our system.
We have been running a refrigerated trailer for 4 seasons and use it as a cooler during summer and insulated storage to prevent produce from freezing during winter. We only run the cooler from the mains power supply either at home or at the market. We are extremely happy with our trailer and the following is a breakdown of approximate cost:
|Replacement Trailer Suspension (increased capacity from 2200lbs to 3500lbs)||$600|
|Polystyrene (pink) insulation||$900|
|Spray Foam for corners||$200|
|Used window AC unit (10Amp, 115Volt)||$100|
|Estimated Farm Labour (100 hrs)||$5,000|
We did all of the work ourselves including insulating the floor, walls, door, ceiling and installing the cooling system.
- We stripped the trailer to the frame but left the plywood floor attached. We did the floor first (tipping the trailer over to do the work (similar to photo below). We put the insulation between the frame under the floor and spray foamed the gaps, then added roofing steel on the bottom to protect the insulation from rocks and weather.
- We welded a frame into the trailer to support the cooling unit.
- We added vapour barrier to the outside (under the sheathing), then put the sheathing back.
- We then insulated the inside flush with the frame and then added a continuous layer of insulation on top of that. We have R10 and R15 in the walls and ceiling (we were limited by interior dimensions to get enough space to fit our bins so the walls are not all the same) and R20 in the floor.
- We used nylon washers under all the fasteners on the exterior of the cooler (attaching sheathing to frame). So the metal frame is covered with vapour barrier, then aluminum sheathing then nylon washer then steel bolt.
- We attached the insulation both with the proper adhesive and nylon bolts that go right through the sides. We made sure that the vapour barrier and the nylon fasteners were used to minimize galvanic corrosion between the sides (aluminum) and frame (steel). This is especially true considering we use it in the salt in the winter and when the cooler runs in the summer there is potential for condensation.
- We purchased a custom made magnetic door seal from Midbek (on Mountain Road) http://www.midbec.com/home.php?language=en_EN .
Note: I undercoated all metal surfaces before adding insulation and have not had any compatibility issues between the insulation and the undercoating yet.
Insulating the Bottom (different trailer, same process) 4in of insulation were used.
Unfinished corners – note the insulation between frame members and the continuous layer in ceiling. You can also see the nylon bolts that clamp the sides together. The corners were spray foamed.
8. We use a COOL BOT to cooler our trailer (http://storeitcold.com/) We are very happy with this system and while we have had a couple of small issues, we are very pleased with the service and short down time. With a 10,000 BTU cooler in our 96inx54inx54in cooler we are able to keep the temperature at 2deg C when the ambient temperature is 28deg C and the trailer is in the sun.
CoolBot with 10,000BT/hr window AC – removed for towing but should be fixed in front
What is Next
We like the system so much, when we outgrew this system we have decided to go with a 7000lb 12ftx5ftx6ft trailer that will be virtually the same.
Changes to Make
1. Fix the air conditioner on the tongue of the trailer, up high in the wall and semi permanently (so it can be removed if necessary for maintenance or replacement). Add a fairing around the cooler to protect the condenser from debris on the road and snow/salt in the winter. We added the cooler on the back and remove it when towing as we were originally using a car to tow with and did not want to add the extra tongue weight. This window has worked well to vend from in the winter when it is below freezing.
2. Add a LINEX spray in coating around the bottom so it can be washed with a hose. (like a spray in truck box liner) http://www.line-x.ca/index.php?page=map&dealer=62
3. Add washable sides and ceiling. This could be as simple as corrugated plastic sign board or as elaborate as dairy barn wall board: http://www.epiplastics04.com/PDF/products/ExtrutechProducts.pdf
4. We are considering stripping the next trailer to the frame, getting it sand blasted and LINEX to coat with a weather proof layer to preserve it from condensation and salt in winter.
Bernie’s Electrical and Insulation (Shemogue) do polyurethane spray foam and can do the inside of a vehicle. He may be able to make this surface flat to mount a washable surface on top of…
A Maranda Truck Cap insulated with a coolbot. We are also going to add one of these to our fleet as it will be transferable to different trucks and could be put on a trailer if it had to. http://paulmaranda.com/en/mobile-workshops/v-series/v-325-v-365 – this will cost approximately $7000 plus insulation and cooling system. Our plan is to use it for a while before insulating it. When combined with our small trailer this would enable our 3/4tonne pick-up to transport almost 6000lbs of product safely and compactly (short wheelbase truck + 8ft trailer + trailer tongue). We will add another 2500lbs of capacity with the larger trailer. It would also enable us to use just the truck during stormy winter weather when the market will be smaller and the trailer not safe to tow.
Atlantic Windows (Amherst) usually has insulated window cut outs from doors that are approximately 20in x 30-36in, 2in thick and R15. When the steel is removed from these they could be an economical insulation (+/- $0.50 each from Atlantic windows). Get the ones without the molding (flat). A hybrid system of these panels on the flat surfaces and Bernie’s spray foam might be economical and with dairy board and a LINEX floor and bottom wall portion. This would be very professional “looking”.
Here is another link for a Do It Yourself version – I think there are some improvements to be made on this version: https://www.youtube.com/watch?v=Vx16FJCFdhg
Here is a link to a more professional approach: https://www.youtube.com/watch?v=mwszYcKOuyA