Aerating your worm bins is a very important part of vermicomposting. Especially if you are in an area that has very hot summers. I have been experimenting with very good success using 3 inch pvc pipes. They are drill with many holes all around and put 18 inches into my 24 inch flow through bins creating an exhaust style pipe in my bins.
I started by placing these pipes in hot spots when my temps would get up into the low 90's or even higher to allow the heat a way to travel up. Mainly this would happen in the spots where I had recently fed the bin. Then I started using these stacks to add the food into when I fed the bins. The idea here was that the heat was insulated by the pvc pipe from the substrate in the bin and that with the 3 inch top open the heat would mostly rise out of the bin only heating the surrounding area a couple degrees over the rest of the bin. It worked fairly well but I was not getting the amount of worms coming into the pipe and feeding as I was when the food was just being added to the top of the bin.
What I decided next was to just leave the pipes in place in the bin and still top feed each section as I was doing before. This has had great success for me. The areas I feed heat up a little bit but only on the top and all the heat from lower down in the bin is being allowed to dissipate up and out the pipe. The biggest thing I like about this is I feed twice a week to keep up with the amount my bins drop every week. One feeding is 1/4th the bin of partially composted feed and the rest is wet shredded boxes. The 2nd feeding is all wet shredded boxes. As long as I keep the shredded boxes wet enough the worms will eat threw it super fast. The problem with this I was having before is water conducts heat in the bin and stops the amount of air flow. This does not allow the heat to dissipate up and out of the bin and instead traps in causing temps to raise higher then I would like and somethings well over 100 degrees. I was using fans and frozen gallon milk jugs to drop temps back down. This can be a pain for so many reason. The biggest though is I am always digging down into the bin turning over the top layers to dig a spot out for the frozen jugs or bottles. This is not very functional in a CFT style worm bin. Ever sense I added the pvc stacks my temps have been on average at lest 10 degrees lower then what I was getting before. I have not had to add any ice jugs and I can keep the bed a little more moist on top so they worms really eat threw the product. Before when I was using fans directly on the bins for air flow the top layer of the bins was always drying out to much.
This has worked for me on several different levels allowing me to increase my feeding habits, spend less time managing my bin temperatures, less time spraying bins and keeps my moisture level more suitable for my worms. The downfalls I have found from this is if the temps drop over night the bins don't build heat as fast but if you put the lid on it will still trap a lot of the heat coming from the pvc stacks. The biggest downfall is of course the obvious loss of space in my bins. I justify the little bit of space lost by how much space was already lost due to having frozen milk jugs or bottles all throughout my bin. I had started by moving one stack as I fed that area and then I just added a new one for the next area that was feed but now I have added one in each of the four feed zones which is placed a little toward the middle of the bin in each zone. The areas around the side get a good amount of air flow already.
I hope this helps anyone that had problems with their bins getting to hot and I also hope it works as well for you as it does for me. How do you keep your bins from overheating during the hotter months?