Looking for feedback on fermentation chamber design

[Steve271828]

Recently, I decided that a fermentation chamber would be the obvious next step for my home brews. I've looked at a few designs, but I haven't been too crazy about them. I want something that can both heat and cool, as it gets a bit cold in my basement in the winter. I don't really want to change frozen water jugs either. So after looking into a few options, I turned my attention to Peltier coolers as a source for cooling.

I drew up a quick design idea that uses a Peltier cooler mounted to a piece of aluminum inside a wooden box filled with water. Attached is a photo which should describe the basic concept. Basically, I was thinking of constructing a wooden box that would contain the carboy surrounded by a small amount of water. One of the wooden panels would have a section cut out which would be replaced by an aluminum plate that is attached to a Peltier cooler (the cold side). Attached to the other side of the Peltier cooler would be a heat sink. I would have one fan dissipating heat from the heat sink and another fan circulating the water in the box. That's basically the extent of the design. Of course the Peltier cooler would be connected to a temperature controller and the fans hooked up to a power source. I'm also thinking that I could extend the sides upward with some foam or additional wood to improve insulation.

I'd like some general opinions on this design. If this is a waste of time for some reason I don't understand, let me know. If there are any slight improvements that can be made, I'm all ears.

In addition to general opinions, I also have some specific questions

• As I understand it, the Peltier cooler hot/cold sides can be reversed by reversing the direction of the current. Is this feasible in this design? I'm imagining that I just connect the Peltier cooler to both the hot and cold outputs of the temperature controller, but reverse the connections.
• I'm concerned about the wooden box leaking water or warping. Is there a good way to seal it? Should I just line it with a plastic liner or something? My only concern with a plastic liner is reduced conductivity of the Peltier cooler. Maybe I could glue the plastic lining to the aluminum and cut that part of the plastic liner out so the aluminum is directly touching the water?
• Should I replace the waterproofed computer fan with a submersible pump?
• Is one Peltier cooler capable of sufficient heating and cooling?

Thanks

 

[crane]

As far as the Peltier goes you can use it to heat if you reverse the current. I've read that a peltier's life is reduced from rapid cycling of power, therefore a normal PID's PWM output would reduce the life of the Peltier. You would want to use an H-bridge along with a temp controller with an analog output.

Now I have never heard if a waterproof computer fan. Generally water inside a computer = bad things. You would be better off using a small submersible aquarium pump.

I have used roofing tar before to create a water proof barrier on wood. It does the job but is a pain to work with. You could use it to seal all of the wood and the seam around our aluminum plate.

I looked into doing and air to air Peltier design before using an off the shelf module that included both heat sinks an fans and to be able to get to lager temps I would have needed to drop $300 for the module so I wet with a $30 mini fridge instead and gutted the compressor out of it. I thought about doing the carboy in water bath like you are describing but I have hard wood floors and don't want to deal with dripping water everywhere each time I have to rack beer.

 

[danz]

There is no real cheap way to waterpoof wood so I would recommend using pond liner or look at using a tub of some sort. A concrete mixing tub from the depot or lowes would work out for a shallow container. I would also look to attach the peltier to a more substantual peice of metal like the Ice Probe

 

[Steve271828]

Hmm.. Seems like the more I research I do into the Peltier cooling systems the less worthwhile it seems to be. I'm trying to decide if I want to try it out just for the hell of it because I think it would be a fun project.

@crane: Thanks for the information about the H-bridge, I didn't know that. I think I've seen some people talk about using an Arduino to control the heating and cooling elements (maybe a Raspberry Pi would work as well), and since my domain of expertise is computer science I may explore this option.

I'm thinking at this point it might be best to scrap wood entirely and just go with a plastic tub like danz mentioned. I have noticed that heatsinks on both sides with a fan on top, one submerged in water, is the route most people seem to take.