A/C

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This post is long overdue, but here is a quick recap of my AC replacement.

About a year ago the window AC unit in the fermentation chamber went out when I was making batch +8.  I’m pretty sure this is the reason that batch ended in bottle bombs.  I wasn’t too disappointed in the AC failing because I felt that it was working more than it should.  It appeared to let a lot of cool air out of the unit itself causing it to kick on more than I thought it should.  So I decided I’d reuse the guts of a small cube fridge.  In hindsight, I wish I had used a bit larger of a cooler as it appears that I can only hold a 35 degree temperature difference.  This is sufficient for fermenting, but not good enough to get a good cold crash when the garage is in the 80s.

Taking apart the mini-fridge was pretty easy once I bought a pair of sheet metal scissors.  From there it was pretty easy to mount the cooling tray and add the insulation.  I certainly didn’t sand and paint as good as I did in the original build, but it works.  Finally, I added a pc fan to continually blow across the cooling tray; without it I noticed that it would ice up when trying to cool.  I’m seeing a bit more condensation that I expected and have a towel to catch things.  I’m trying to limit the amount of times I open and close the fridge for now, but this is something I’ll have to keep an eye on.  All in all, it works and I’m back to brewing!

 

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Trying to start a project just as you become a dad isn’t the best plan, but I’ve finally completed my fermentation chamber after about 6 months.  I’m already making a beer in it and so far it is working great.  The ironic thing is that the temperature is about 70 degrees right now and the fermentation chamber doesn’t really have to do anything, but at least I’ve staying at a constant temperature.

First things first, here are pictures of the completed project  (click an image for a larger view)

 

Supplies

I bought my things from four main places.  The temperature controllers came from E-bay, the A/C unit was from craigslist, the 110VAC lights, switches and relays are from Allelectronics.com, and the rest of the material was from Home Depot.  The box is made of 2x4s, 1/4 plywood, and 2 inch foam.  I used foam glue to attach the plywood to the foam and 2″ screws to join all the 2x4s.  To join the foam pieces together and cover holes I used Great Stuff.  After I add up all the pieces I spent just a bit under $500.  I bought a few tools, but was able to borrow most of the big tools from family and friends.  The most surprising thing was how expensive outlets, outlet boxes, fuse holders, and  the controller box were.

The Build

Overall the project came together pretty close to the plan.  I can’t cut straight, follow my directions, or paint, but other than that I did pretty good.  The borrowed tools really helped cutting relatively straight lines, not straight, but straight enough.  When I built the controller box I had a few errors that needed correcting, but that was fine and not completely unexpected.  I also didn’t like how my doors were going to seal so I added another foam border to help with that.

The control box almost was a disaster.  I used a bremel to cut out the switches with no problem.  The wiring went to plan.  I did have a bit of difficult soldering the wires to the switch contact points, but eventually got it.  the I used a few contact boards to provide a secure attach point for the external wires to the internal wires.  At the very end I almost couldn’t get the lid to close.  I had to move and twist the wires around and apply some pressure to finally seal things up.  I had two mistakes during this build.  First, my initial wiring for the relay looked really good, but upon testing I discovered that I did about 50% of the connections wrong and had to redo it all.  Finally, once it was all sealed up I discovered that my compression did break a couple of contacts that I had to go in and fix.  But in the end the controller works great and looks pretty good.

As an extra thing that I worked on while I couldn’t get down to the garage is that I converted two old cell phones into IP webcams, one to watch the control panel and the other inside the chamber to watch the fermenting process and to double check temperatures.  To get my wifi signal to reach the garage I had to setup a wifi repeater.  The two phones were android phones and I was able to use free apps to setup the webcams.  I installed IP Webcam for the webcams, droid VNC server to get into the phone remotely along with Screen Widget to turn the screen off (if needed).  Finally, I can watch the webcams with the built in webpages from IP Webcam and I also use IP CAM Controller to see things from my phone.  I had planned for this which is why I have an outlet not controlled by the STC-1000s so that the internal cell phone could remain on all the time.

Here are several photos during the build  (click an image for a larger view)

Looking Back

Now that I’ve build my project I think I’d do it a bit different next time.

  1. I’d probably simplify all the cuts I have to do and make the outer plywood fit around the foam entirely then have the 2×4 brace around it.  This would make the project cost just a bit more, but it would save so much time.
  2. I’d make the doors fit flush with the outside edges rather than fit inside the openings to make the seals easier.  I didn’t follow my original plan for the doors as I was worried they wouldn’t seal well.
  3. I would make the A/C cutout a bit larger.  This ould make it easier for the great stuff to get in the cracks.  I didnt’ have much space and don’t really know how well I sealed this in. (I’m yet to do a dry ice test).
  4. I was excited and cut the foam pieces first, but looking back I should have made the frame and then cut the foam to fit into it.  I’m pretty sure my method is a rookie mistake, but I was excited to see the foam cut out.

 Next Steps

I haven’t made the dividing section so that I can have two temperature zones inside.   I have the controller and the wiring all done and all is left is to figure how I would do this.  I’m thinking some type of relay to open and close a small opening and then a fan to circulate air.  I also have to figure out how to make the section so that it can be moved around and then “expanded” to give it a tighte fit.  I’ll have to think about this for a while, until then…

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