Fermentation Controller Part 3

Well, I finally got around to finishing this off and testing it. It seems to work like a charm.

Fermentation controller part 2

DSC01222bannersmallSo, this project has been languishing because I have had difficulty locating a machinist willing to machine a part, and I am too lazy to make a perfect measurement not he outside of the conical fermentor, which is required to maximize the metal on metal contact required for this application. But lo and behold! Stout Tanks and Kettles once again comes to the rescue with a made to fit kit for my fermentor. Now, you have to buy the machined piece AND the fans together, so I am out money on the fan I already bought, but it is worth it just to have the thing finally made. I have finished the wiring tonight and begin testing in the morning.

Here is a bit more about how the thing is made. In the last part (part 1) I had managed to machine the case with my drill press and a sliding table. Now the electronics start!

I bought a few items: an Auber Instruments 2342-P and a Jetstream JTPS31MB variable power supply as well as a bunch of SSRs, relay switches, and other components to be mounted on a DIN rail. The jet stream unit is secured with some washers and screws. The PID has a plastic tab that secures it pretty well to the face, and can be better secured with some screws, as well. I decided to use the screws, which I normally don’t bother with, but I want it to be pretty rigid since the space inside is so tight. This secured everything very tightly. The enclosure is small considering the size of the components I am using, and it was a bit of effort to make sure everything was aligned properly so things didn’t bump together. The tightest part is the DIN rail mounted components. If there was a small DIN mounted DPDT contractor that could take 30 amps in both the open and closed position it would have made this much easier, but I couldn’t find one.
So instead, for the polarity switching I had to use two DPDT switches together. Unfortunately, with the one for the power relay, almost 2/3 of the space was filled with contractors and it didn’t leave much space for the terminal blocks. Out of absolutely pure luck, the needed components just fit to the point where not a single terminal block more could fit in there! In order to make sure it doesn’t overheat while running, I drilled holes in the side panels for ventilation, and installed a fan on the back wall with grooves where the fan blades are.

I wired it up and tested the internal components, and everything lit up like it was supposed to, but I was having a lot of trouble sourcing the business end of the thing... the part that heats and cools and attaches to my fermentor. As a matter of fact, I couldn’t find someone to machine the thing for a year (not that I tried that hard). And then, one day in February, I found that the company that makes my fermentor started to produce a kit with the machined part I need! I ordered one as soon as I saw it.

It came with 2 fans, as well, but I found that to make a tight fit, I had to file down the posts to lower the fans by a mm or 2. I decided to use switchcraft high power panel mount connectors so it would be easy to plug the heating elements in, and because they were pretty cheap. I covered the aluminum block with 1/4 inch closed cell foam tape to insulate it on the surfaces that don’t contact the fermentor, and drilled holes to connect a power block. I then cut out holes where the Peltier chillers were to go, and used goo gone to clean up the surface. I am using 9amp Peltier coolers, but can’t remember where I got them. A coat of thermal paste between both the Peltier and the block, and the Peltier and the fan, and I assembled the whole thing. I tested it for a few minutes.... everything powered on, the fans all turned, and a nice layer of ice built up on the chiller within a few minutes.

THE THING WORKS. The picture below shows ice building up on the metal.


DIY Hop Torpedo

So, after having ruined several batches of beer with dry hopping and having hop particles fall out of the bag, making the beer bitter and grassy, I decided it was time to make a change. I had always been curious about recirculating while dry hopping, and the benefits I would think could be made from this. Sierra Nevada has perfected the system using their “Torpedo.” This is more like a Hop espresso machine-- they compress hops together and force the beer through it at 50 PSI. While my DIY hopback could handle the pressure, I don’t have the technology to compress the hops, nor to generate that kind of pressure gradient across the hops without having to do a LOT of work. So, rather than do this, I thought it would be much easier to just make a recirculation dry hopper. I already had my hopback, which is designed to work perfectly in this situation, as well, and so I just needed a very slow pump and some connectors to make this work. I figured the easiest way to do this was to dry hop straight from a cornelius keg, so I could keep things sterile, and it already has a dip tube and a return tube (the gas inlet), making construction MUCH easier.
Here’s what I did. I bought a single speed peristaltic pump (Anco 907-058 pump) that was rated for continuous use (very important that it is rated for continuous use). At 58 RPM using 1/4” ID tubing, it pumps about 3.5 ml per second, or about a gallon every 18 minutes. I attached this to some 3/16” beer line on both ends of the peristaltic tubing with a 1/4” stainless hose splice, then to a black (liquid out) ball lock quick disconnect. On the other side of the pump’s peristaltic tubing, I connected 3/16” beer line to a 1/4” to 1/2” hose adapter into a 1/2” female stainless disconnect. Another cord was made with 3/16 beer line with a gray (gas in) ball lock quick disconnect, and on the other end another 1/4” to 1/2 inch hose adapter to a 1/2” female stainless quick disconnect. My Hopback has been fitted with male 1/2” stainless disconnects, so it can clip between the two cords.

Here is how it is used:

I fill a Cornelius keg with at least a gallon of Starsan. I then plug both of the quick disconnects onto the keg, place a hopback bypass connector in place of the hopback, and start circulating the Starsan through the tubing. In the meantime, I place the stainless hopback into the oven at 350 to sterilize it, and I let it cool, and fill it with hops (up to 5 ounces).

Flushing lines with CO
After recirculating Starsan for a while, I remove the quick disconnects from the keg, and place the “gas flush input” on the liquid out quick disconnect, and the “gas flush valve” on the gas in quick disconnect. The crummy thing about this setup (with my pump, at least) is that in order to force the stars an out, the peristaltic tubing needs to be removed from the machine. This means I have to unscrew the cover, and screw it back in once the tubing is replaced, making it more of a pain to use. I close off the gas flush valve, set the CO
2 pressure on my regulator to 5 mmHG, then plug the gas flush input into the CO2 quick connector. I then slowly open the needle valve and slowly drain the liquid out of the lines until CO2 flows out, then I close the valve and disconnect the CO2.

Flushing hops with CO
Once all the lines are clear of Starsan, I replace the hopback bypass with the sterilized and filled hopback, and reconnect to CO
2. I open the gas flush valve a bit more and let CO2 vent to the atmosphere for a few minutes. This purges all the air from the hops and hopback.

When air is purged from the hopback, I spray Starsan over the gas in and liquid out posts of the keg to dry hop to sanitize it. I disconnect the gas flush input and place the quick disconnect gas flush valve on the keg. I also remove the gas flush valve and place the gas in quick disconnect onto the keg’s gas in port. I replace the peristaltic tubing into the pump, and then turn it on. My plan is to recirculate for a total of 3 days, and no more.

I am running a test right now, with the first sample running. I have a Bavarian Hefeweizen that I brewed 2 years ago, is not very good and has been filling a keg. I’ll probably never drink it but don’t have the heart to throw it away. Instead, I will sacrifice it to science! I am currently dry hopping it with 4 ounces of citra… not the most normal choice for a bavarian hefeweizen, but something that will definitely be noticeable, and with the light flavor of the hefeweizen I think this will be a good test of what the process does. I’ll let it run for a few days, and report back.

Parts List: Number
Cornelius Gas In Post 2
Cornelius Liquid Out Post 1
Cornelius Gas in post to 1/4” NPT female adapter 1
Cornelius Gas in Post to 1/4” NPT male adapter 1
Cornelius Liquid Out Post to 1/4” NPT female adapter 1
Noshok 1/4” Male NPT Needle bleeder valve 1
1/2” NPT stainless mail to male quick disconnect 4 (2 for hopback bypass, 2 for hopback)
1/2” FPT stainless female quick disconnect 2
3/16” beer line 10 feet
Ball lock gas in quick disconnect (w/ swivel adapter) 1
Ball lock liquid out quick disconnect (w/ swivel adapter) 1
1/4” stainless steel hose splicer 2
Hose Clamps 8
Peristaltic pump with rate of approx 2-3 ml/sec 1
Hopback 1

Update 2/18/13: The hefeweizen took on a huge flavor and aroma of Citra. The project is a success!