I'm Back!

Hard to believe it's been almost a year since I posted, I've had a few things come up that put the project on hold, but I'm ready to start wrenching again.  I've built the physical chamber and done most of the electrical wiring, now I need to get the Beaglebone Black up and  running again and get my software tuned up so I can start controlling some fermentation temps.

I've been mainly working on the physical chamber and I've got a few pictures of that to share.

Ferm Chamber with Rough AC cooling placement

Air Conditioners have their own built in thermostats, and this one doesn't have an option to just run the cooling cycle all the time, so I had to hack the unit up a bit to re-route the very analogue temp probe from the AC out of the chamber and somewhere I could access it to to heat it up when the Beaglebone wants to cool the chamber.  The probe on this unit is a closed loop refrigerant coil that connects to a baffle that is opened and closed when the coolant in the line expands / contracts due to the temperature of the air coming into the unit.  It is normally mounted about 1/3 of the way up from the bottom.  Thankfully the copper is pretty malleable and I was able to bend it without crimping it out the back of the unit.  The end result can be seen here.

Re-Routed probe.

You can see here I managed to get it coming out the back of the unit where I now have easy access to it.  I will build up a little heating circuit using the BBB so that when it wants to cool the chamber it will also heat up this little guy which enables the compressor.  The other option is to just short the compressor to the main power which would always enable the cooling, but that's a bigger operation and if I muck it up it will render the AC unit useless.  I'm all about non-destructive modifications so I'll stick with this method for now.  For the heating I'm thinking I'll use one of these 5V heating pads which should be easy to control from the BBB.

The inside of the chamber is insulated with 1.5" R5.6 Foam insulation from Home Depot.  I used it because it was cheap and easy to work with.  I can always increase the amount of foam if I find the efficiency is bad, a quick test earlier showed no heat gain with a half hour stand and a 15 degree C gradient between ambient air and the chilled chamber air.

Since the unit is in my garage, and I live in Ottawa where the outside air temp can hit -30C I need a way to heat the unit as well, my brewing buddy Steve suggested I use a ceramic bulb like those used for lizard setups, which he happened to have.  So I wired up a hot side SSR controlled circuit and added a ceramic lightbulb outlet to the inside of the chamber that's controlled by this circuit.

Heater bulb outlet and the Temp Probe XLR headers.

You can also see in this picture the temperature probe headers I wired in.  On my old chamber I simply had the temperature probe wires just run through the chamber wall directly, but that can get messy and meant disconnecting them from the board to clean / sanitise them between brews.  This way I can pull them out when not in use and store them easily, then move the beer in, plug in the probes and I'm ready to go. It's also easier to add the probe to the wort before you move the carboy into the chamber ( more headspace for a 16" probe to be inserted ) so now I can put the wort probe into the carboy and then slide it in and plug it in after.  Plus XLR's are pretty damn awesome, I feel a little bit like a Rockstar when I plug them in :).

The last picture is a bit embarassing, but there's a mess of wiring coming out of this thing and I didn't plan the layout very well, I got really excited about getting it hooked up and just kind of ran with it.  For some reason the picture is showing up really small, I'll try to get some better shots for the next post.  This is the outside wall which has the control box for the SSR's, out of the box comes some Romex which connects to the hot and cold side plugs, the AC plugs into the cold side plug and the Light box is wired up in series to the hot plug, so when that circuit is energized the bulb is also turned on.  I may run a line for a small fan at some point for the heating side to help move the air around.

Black box has the SSR and Input voltage, you can see the AC Plugged into the cooling circuit.

I'll have a few more pictures and a new post in the coming days as I get the software side of things ramped up again and start doing some test runs before the inaugural brew.