by Farmhand » Sat Sep 28, 2013 9:16 am
Here in Central Queensland, its difficult, at night the temps can go down below 20 and during the day up to 38 or 40 degrees, here is what I did with my first 65 liter barrel, I sat the barrel in a pot plant reservoir and put water in it so as to make a moat to keep out the ants, which can be filled with cold water or hot water in an emergency, I use the resistive heat chord for keeping snakes warm, it uses about 30 Watts, I wrapped that neatly around the bottom of the barrel at about 150 mm from the ground with 20 mm spacing about between wraps it goes around about four times, all taped in place, then I use bubble wrap thick around that and most of the barrel leaving about 100 mm above and below the bubble wrap, I then cover with aluminium foil, I use the heat chord on a timer so every two hours it comes on for 30 minutes during the night, first on time is at 7:00 pm and last on time is at 6:00 AM that keeps the barrel between 25 and 28 degrees during the night but some days it wants to go above 30 even to 35 so then I employ evaporative cooling by wetting the concrete around the barrel, filling the moat with cold water and using a wet cloth around the lid which has a kind of moat around the outside edge as well, then of course the fan, I've only had one day when I needed to do the cooling.
In a colder place the 30 Watt heat chord would not be enough, and either a higher wattage - longer chord or a higher power consumption chord might be needed. I think the bubble wrap and the al-foil helps a lot to keep the temp more stable but there does need to be some input heat at night. I have no heating or cooling in my hut i use for all my extra fun activities and experiments.
I'm into electronics a bit as well and I'm working on designing a "thermoelectric module" (Peltier module) based heater/cooler which would be reversible as in heat or cool and controllable with a microprocessor or some other even simpler method, very too busy for electronics at the moment, that requires time and hard thought for me to have success.
Depending on the fermenting vessel size/shape and what it's made from determines some things.
Heat chords for reptiles are fairly cheap effective and fairly safe as well if used with a timer/thermostat. I got mine on Ebay cheap and will be getting another for the second barrel and may even fashion them into a sleeve type arrangement so they can be slid on over the top and taken off to clean the barrel. I think I get one with more power consumption or is longer or something to use in shorter bursts or during winter. I'm very happy with the stability of my barrel temp the way I set it up it stays between 25 and 30 very well.
Kinda gotta find a balance between insulation/heat retention or heat loss and heat input the less heat is exchanged naturally the less we need to do.
Cheers