This spring I started a worm farm at the food bank/community garden where I work to help manage some of the cardboard and old produce that piles up here. I've been doing everything on the cheap with materials we already have (not a lot of money in food banks right now) and have 8 breeder bins in some outdoor shelves previously used for storage. We're in the southwest US so once summer hit we started having real problems managing heat, which meant I had to come over every day to swap out ice packs. I built this low tech little cooling system with irrigation tubing, a solar powered pond pump, and a bucket inside an insulated tub to get my weekends back and it works way better than I expected!
The tubes run through cut out slots in the sides of each bin so they sit low enough to be in contact with the bedding. The same tubes run through all of the bins. Water is pumped out to the last bin, makes a u-turn, and is returned to the bucket the same way it came up. There's also a spout and some valves off the return pipe so I can drain the system when I need to without trying to move the whole bucket set up (not really necessary but I had the parts so why not)
Regardless of outdoor temperature all bins have stayed consistently 70-80 degrees since I put it in a month ago, compared to swinging from 68-98+ before. The water in the bucket is around 75 degrees most of the time and only pumps during the later part of the day when the sun hits the solar panel, but that seems to be enough. The worms are happy and this solution should keep things nice and stable until we can build a shed for the worm farm, hopefully in the fall. At that point we're planning to transition to mostly large wedge bins- right now we're just breeding enough worms to get a system started that can handle 100+ pounds of cardboard per month.
I thought I'd share my set up since it worked so well and was so easy. It was essentially free and has pretty dramatically reduced the time that goes into maintenance. It turns out a food bank is the perfect place for a worm farm and we've had a great time getting it going and getting the community interested and involved!