As per my previous notes, the external heat sinks on the system, as per the instructions, were not big enough on the exterior of the module to provide adequate cooling. My solution was to water cool the peltiers, however I need a water block that is big enough to span two peltiers.

Below you can see what we are building today.

Index
Step 1 – Drill main cooling channels
Step 2 – Drill first cross channel
Step 3 – Drill the rest of the cross channels
Step 4 – Drill and tap and fit the grub screws
Step 5 – Drill and tap and fit the barbs

Tools Required
Drill Press
11mm drill
5-6mm drill
Drill and tap to suit barbs
Drill and tap to suit m6 grub screws
Loctite thread adhesive

Parts List
100x50x20 Aluminium block
2 x Water cooling block barbs
4 x grub screws
Loctite thread adhesive

Step 1 – Drill main cooling channels
A couple of things to take into account before you start. When you are creating something of this type, by machining a chunk of metal, it always pays to plan it out properly. I am as guilty as the next guy of just picking up some bar stock and going for it, but inevitably that leads to making something that either doesn’t quite fit, or just doesn’t work.

So, draw out what you are building and try to account for all eventualities. In this case there are a few traps.

1. Make sure that the first thing that you do is work out where the bolts are going to go that hold the water block down to the peltiets and heat sink. As per the previous instructions you will have 8 holes in the main heat sink block that at your disposal. I figured that I probably only needed the outside 4 in order to hold the water in place, so marked out the locations of where I needed to drill the holes.

2. You are going to need two large holes that run the length of the block, but dont come out the other end. They need to take into account the mounting holes that you just marked out. You want them to be in each corner as you can see in the model below.

In drilling a hole this large, it is best to use a pilot hole first. What I did was to drill 5mm or so into the aluminium block with the large drill so that I was sure that positioning was correct, then swapped to a much smaller drill. It was easy to position this smaller drill as the first large drill left the centre point.

TIP: make sure to use the depth stop on your drill press so that you dont break out the bottom of work piece.

Once you have drilled the pilot hole, you will probably want to go for a larger pilot hole as well. Once that is done, go for the final size. In drilling aluminium, you will probably want to use a lubricant to avoid the drill sticking. Aluminium lubricant is generally  Kerosene.

One hole done, move the work piece over and repeat for the second hole.
Step 2 – Drill first cross channel

Now that you have both those holes drilled, clean up the work piece to remove all the swarf (waste metal shavings) from the holes and plan out where the cross holes are going to go.

I chose to have 4 cross channels, figuring that it was probably adequate to have two per peltier. You will want to draw the peltiers location on the block so that you can see how it is all going to go together in order to get the holes in the right place. If all else fails, make them evenly distributed and it should be fine as well.

Again, you are going to want to only drill most of the way through. You will go right through the first big channel and into the second, but no further.

Here you can see the first cross channel drilled.

Step 3 – Drill the rest of the cross channels
Once you have drilled the first cross channel it is simply a matter of drilling the other 3.

Once you have them all drilled give the bock a good clean to remove all the excess.

Step 4 – Drill and tap and fit the grub screws
Now that we have the cooling channels all drilled, we need to seal off the outsides of the cross channels. This will allow the water to flow through the block, in one large channel and out the other. In order to accomplish the sealing off, we are going to drill and tap the small holes and insert a grub screw.

I chose M6 sized grub screws but you can use whatever you can get or feel adequate.

You want to drill into the block for the depth of the thread with the recommended size drill for the tap that you are using. THis will mean drilling into the first large channel.

Tap the 4 holes next and test fit your grub screws. You should have a nearly completed water block at this stage, however the grub screws will not be water tight. In order to fix this get some thread adhesive. Loctite is a popular brand. You basically just coat the hole and the grub screw with the red fluid and screw them into place. It will take about 24 hours to dry, but when dry your block will be water proof.

Step 5 – Drill and tap and fit the barbs
To connect the new water block to the water cooling loop, you are going to need barb hose fittings. Again, these will need a particular sized drill and tap. Drill the holes and tap them to suit.

Screw in the barbs. If you have barbs with an ‘o’ ring, then you wont need to loctite them.

Drill hour mounting holes as you market previously, taking care to ensure that you wont drill into any channels and you are now finished.

An important step is to check the new water block for any leaks. Plug it into your water cooling loop and run it for an hour to see if any water leaks out. If it doesnt then you are ready to go and move onto the next step.

Next tutorial is to fit the water cooling system to the cabinet and mount the water cooling block to the heat sink.

Part 4 of the previous heat sink post.
To recap…..
We have built the aluminium bar into a heat sink with peltiers and heat sinks and fans, we have been able to  fit it to our fermentation cabinet, now it is time to wire it all up for control.

Below you can see what we are building today.

More after the break

Index
Step 1 – Build a top for your Cabinet
Step 2 – Wire up a socket and attach all 240v devices
Step 3 – Fit the peltiers and heat sinks
Step 4 – Connect the peltiers
Step 5 – Fit and wire the relays
Step 6 – Bridge Rectifier
Step 7 – Fan Power Circuit
Step 8 – Add the other components

Tools Required
Electric hand drill
Screwdriver
Jigsaw
Soldering Iron and solder

Parts List
Assembled aluminium block from part 2
8 x self tapping screws with flat head
Wood screws
Blue LED
Red LED
Electronic temperature controller
2 x computer case fans
2 x 15v 8A power supplies
IEC 3 prong socket with switch
Numerous screw terminal strips
Bridge Rectifyer
1mm Copper Cable in black and red x 5m
Heat shrink

Optional
Vero strip
4 x 3 pin computer fan headers

Step 1 – Build a top to your Cabinet
At the moment the top of my cabinet is flat. It will be difficult to contain everything the way that it is, so I want to have a top added that will contain all the electronics in a separate compartment.

Above you can see that I have cut 4 pieces of MDF and fixed them to the cabinet with 10mm square battons and screws. I intend to paint this cabinet at some stage, so keeping everything as flat and as square as possible is preferable to keep the Wife Approval Factor as high as possible.

The temperature controller mounted to the left hand side of the cabinet top. I picked this location as it seemed to be the most appropriate place for me, but yours may be totally different of course.

In order to know what is happening with the fermentation cabinet at a glance, I have fitter a bright blue LED and red LED to the right hand side of the cabinet top. I dont have a tutorial on how to use LED’s but basically you need to wire up a resister inline with the LED to ensure the correct voltage. The specific resister needed will vary based on what LED you have, but generally a 300ohm resister will suffice. I found these neat little mounting caps that made it real easy to mount them in the MDF. Just drill a hole and clip the in.

In oder to shift the heat form the power supplies and the heat sinks, we better have a few case fans in the cabinet. I chose two fans that I already had for the job.

Step 2 – Wire up a socket and attach all 240v devices

NOTE: In some countries using 240v (or 110v or whatever your local mains voltage is) in a project like this, without appropriate electrical qualifications is illegal.
Regardless of that fact, you should not undertake any mains voltage work without the proper know how or precautions. I cant teach you these, but this step in the process is unnecessary, I wanted to tidy it up a little. If you are not comfortable or have no knowledge in this area, then just use a power strip and plug in your mains voltage components to that and save yourself some potential grief.

Warnings out of the way, lets get on with it!

I found this neat fused, switched IEC chassis that takes a standard 3 pin machine plug.

Here is the back. You can see the ground, active and neutral pins on the right, and the switch on the left.
Due to my warnings at the top of this step, I am not going to show an in progress shot of this step, but suffice to say, solder on the neutral and ground of each connected device is connected to the relevant posts on the back of the socket and the active is switched.

Take your plug and cut the mains connector off.

Strip the end to reveal the active, neutral and ground cables.

Connect the cables and heat shrink the back to make it as safe as possible.

You are left with the temperature controller wired in, and two power pack plugs ready to plug in the transformers.

The switch ends up on the outside with the socket.

Step 3 – Fit the peltiers and heat sinks
Simple step. Use your heat sink compound and smear onto the bottom face of one peltier.

Use your finger or another appropriate device to get an even coating over the entire surface that is a regular thickness.

Press the peltier to the face of the aluminium block heat sink, being careful to ensure that you have it the right way up. (there is no actual right way up , they are both identical, but you want to ensure that they are both the same direction) Smear the top side of the peltier and smooth out as you did on the under side.

Repeat this step with the second peltier, being careful to ensure that they are both the same way up.

Fit the heat sinks then the fans to the heat sinks. Be careful not to over tighten the screws.

Step 4 – Connect the peltiers
Now, this step is going to seem complicated for the uninitiated in electronics, but bear with me, and dont be afraid to ask any questions.

Cut 4 terminals off your strip of terminal connectors, and screw it to the cabinet near the peltiers. This is where we connect the cables coming out of the peltiers. The cables will be black and red, and you should connect them as I have above. Push the stripped end of the cable into the connector and screw the terminal down until it is tight. NOTE: dont over tighten them, just a nip up from being finger tight.

The terminal strip that we just connected is on the right of this image above.
In order to do our magic swapping of the polarity we need to built the configuration as showed above. What we are doing is taking the black from one side of another 4 way terminal strip and connecting it to the red from the other side, and visa versa.

Now add in the second side, which is a duplicate of the first. This gives us separated circuits for each peltier. This is important as seeing as the peltiers are 6A and our power supplies are 8A, we need to power each peltier separately,

Step 5 – Fit and wire the relays
Now that we have the peltiers taken care of, including out tricky polatiry swapper, we need to install the relays that will drive the polarity swapper and the peltiers. The relays are activated (energised) buy the power supplies and the temperature controller and will supply the appropriate polarity to the peltiers dependent on whether heating or cooling is needed.

I chose to use relay bases, but you dont have to, it just made prototyping easier for me and the connections are much nicer to make.

Fit the relays. These are 12v-15v Double Throw, Double Pole relays.

The relays are driven by the temperature controller, so a common positive lead needs to come from the power supply and go to a pair of relays and the temperature controller. In the image above you can see that I have used a pair of terminal strips and joined them together so that the positive power connection will be plit to 3 different wires. One goes to the common connector on the temperature controller and the two others go to the two relays on one terminal of the coil each. ie this is going to power the relay to cause it to latch.

We now repeat the terminal strip pair with another one for the negative. This 4 wires coming out, that go to the pole on each relay that will be be switched and to the top of the connector to energise the relay. The heating and cooling contact points on the temperature controller are connected to the relays, one goes to the switched connector on each.

This is reasonably important as you might have to swap these if your system heats instead of cools at the appropriate time.

We now can connect the right hand side output of the relay that matches the switched inputs that we just connected. These are connected to the terminal strip that we connected previously that goes to the peltiers.

Now, we have to repeat the process for the second set of relays. It is exactly the same process and in order to accomplish it you will have to add an extra cable to the connectors in the temperature controller.

Step 6 – Bridge Rectifier
OK, we now have done the heavy lifting, but we need to connect the fans so that they will run whenever we are heating or cooling. This should be pretty easy and just a matter of connecting the fans inline with the peltier output. There is an issue with this though, we need to have the fans the spin the same way regardless of the polarity of the output, and that computer fans will only run on one polarity in any case.

To accomplish this we need to use a small IC device called a bridge rectifier. What this does is take any polarity input and rectify it to always be the same polarity output. Super easy! just connect one to the output of one relay as it goes to the peltier and the fans to the other side. The rectifier has two pins that are marked as ‘~’ these are the input and it doesnt matter how you connect them, the output pins are mared ‘+’ and ‘-’ and should be connected to your fans in the correct polarity.

Step 7 – Fan power circuit
I wanted to have a reasonably modular setup, so I built this little board and put fan headers on it so that I could plug and unplug the fans. You could just solder them all together however, it is up to you.

Step 8 – Add the other components
So we are basically done at this point. Add your transformers and be sure to wire them up to the same polarity. Route your cables and make it all nice and tidy. If you want to use the coloured LED’s then they are wired up to one pair of outputs from each of the relay outputs for one set. You can see them in the image below in the lower right.

You can now turn the system on and see what is going on. Set your temperature controller to be heating. You want to see a red LED on and the internal heat sink should get hot. If this is the case then everything is setup as it should be. If the LED is wrong, but the heat sink is right, then swap the relay that the LED is connected to. If the peltiers are wrong, ie the temp controller is set to heat, but the internal heat sink is getting cold, then you need to swap the cables that are coming out of the temperature controller.

That is the end of our wiring tutorial.
After building this iteration of the fermentation temperature control system, it became apparent that I had inadvertently stumbled upon a bad design. In order for a peltier system like this to operate in the best way, there needs to be an imbalance in the heat sinks in order to let the inside cool the most.

The outside heat sinks need to be much bigger than the inside heat sinks to allow for the best dissipation of the heat that is generated. In my earlier versions I had had BIG outside heat sinks by luck, and this version I was going for good looks and a low profile. In actuality, the heat sinks that I used on the top were not big enough, not letting enough heat dissipate. As a result the internal heat sinks didnt get cold enough.

The answer was to just allow for much more cooling on the top. I could have used bigger heat sinks, but wasnt interested in a big trial and error experiment, so I opted to go for water cooling. I had water cooled a single peltier in the past and knew that it would work wonderfully, so I had to come up with a plan to water cool two peltiers.

Stay tuned in the next post where I build a water cooling unit to replace the outside heat sinks.

Background

About 10 years ago I bought myself a simple thermostat from a hydroponics shop that would allow me to have some control over the temperature of my wort during the fermentation stage.  The theory I concocted for myself (and was not validated by someone who understands the physics of temperature control) was that if I could control the ambient temperature of the air surrounding the fermenter (in Australia we don’t generally use the term “carboy”. The most common term here is “fermenter” and this is the term being used in this article) containing the wort then I could reasonably expect that the temperature of the wort would be more or less the same as the ambient temperature.  I was really tired of having to make a point of checking the fermentation cabinet each day to make sure all things were as they should be and manually switching on lights to heat the wort or open the door to let some heat out.  I wanted a solution that I could “set and forget” until fermentation was well and truly done AND leave me reasonably comfortable that I could rely on the solution to keep my prized wort where it should be temperature wise.

I am happy to say that to this day I still use the thermostat but it does have its limitations.  For a large number of these 10 years I lived in Brisbane, Queensland, Australia where the temperature all year round is extremely moderate, typically around the mid 20s in winter to low 30s in summer.  This was a main factor that allowed me to use a heating only thermostat in a reasonably well insulated cabinet quite successfully.  The other factor was that our garage was under the main roof of the house and was insulated.  Some time ago we moved to Toowoomba, Queensland where the temperature variances are not so moderate and can change significantly and quickly, also my home brew setup in now in a 6mx6m (approx 20′ x 20′) tin shed.  I can distinctly remember one day where we had the air conditioner during the day as it was very hot then had the heater on that night when a cold snap moved in!

Since moving to Toowoomba I have purchased a cooling thermostat, one which switches something on when the temp gets too high, and have set up an old fridge as the cabinet for brewing in summer.  I still use my main cabinet with the heating thermostat for brewing in winter.  Both work quite admirably but it relies on the ambient temp of the shed staying on the right side for the thermostat and cabinet I have chosen for fermenting the brew.  That is, the ambient temp of shed must be lower than thermostat setting on heating thermostat OR ambient temp of shed must be higher than thermostat setting on cooling thermostat.  Most of the time this has worked ok but when weather changes unexpectedly and remains for a number of days I have had to intervene and manually “fix” the temperature problem.

Computerization – Temperature logging: the input

The other nagging question in the back of my mind has been “how right am I on my theories of maintaining wort temp by maintaining ambient air temperature”? The only way to effectively do this is to somehow hook up a computer to various temperature reading devices and record the data.

I am happy to say I have successfully completed this task and provide the statistics of my first “logged” brew for you to view. After looking at the graphs I can say that my theory was “partly” correct however I did manage to maintain a reasonably accurate ambient temperature of the wort for the full duration of the fermentation stage. Due to unforseen circumstances the wort sat for 11 days before bottling but that has not affected the brew at all, it just means there is more data. My brews are typically ready for bottling between 5-7 days.

The fermenter and cabinet setup

Here is a picture of my fermenter in the cabinet. The pics were taken after the brew was bottled, thats why the fermenter is empty. Note the points where the sensors are located.

Here is a close up of the wort sensor. I cut an insulated cover of 10mm neoprene to protect the sensor from the cabinet ambient temperature and all is held in place with duct tape. The actual sensor is located about the middle of the neoprene cover. I dont know for sure how acurate this was as the placement was another theory. I will be running a test soon with the wort sensor in place as well as a sensor in the liquid (probably just water, as a test) to see what variances might be between them.

Here is a close up of the thermostat. It runs on 240V AC. I set the temp I want to maintain with the dial and when the temp drops too low below the setting the light comes on. The switch on the left allows me to switch off the thermostat. If you look closely you will see the Globe sensor held in place with duct tape on the top of the thermostat control box on the right.

Here is a close up of the thermostat sensor with my sensor attached to it. I was able to obtain accurate information about what temperature the thermostat switched on and off at (called hysterysis). The silver probe is the sensor attached to the thermostat, the black probe is my sensor attached to the computer.

Computerization – Graphing the results: the output

Click on any of the days in the calendar control below to open a graph page in a new window to see that days temperature logs. Once the graph page is open you can scroll through the various days. The links to last 12 hours and last 6 hours allowed me to see what my brew has been doing lately when it was live – it probably doesnt mean much here. As I started the fermentation stage at 4:30pm on Sunday 10th October, the 24 hour period starts and finishes at this time each day. The logging was switched off at about 8am on the 21st October.

There are 5 temperature sensors:

Wort: duct taped (100mph tape) to the side of the fermenter and insulated from cabinet ambient temp with a piece of neoprene (stubbie cooler material).  The first few days I was insulating with a folded teatowel so I changed it when it “seemed” to me that it wasnt providing accurate temps.

Globe: this sensor is placed about 5cm from the globe that is used to heat the cabinet.  I wanted to see when the globe was switched on and when it was switched off.  This worked very well. This data allows me to estimate the electricity running costs for the brew.

Sensor: the sensor is actually taped to the sensor probe of the thermostat.  This is located near the bottom of the fermenter which is about the middle of the cabinet.  This tells me the hysterysis that is programmed into the thermostat I have been using (which I have never known until now).  This is preset and I cannot adjust it.

Shed Ambient: the ambient temperature of my tin shed.  This temperature is extremely important as it is one of the most important factors dictating the internal ambient temp of the cabinet.  The other factor that is equally important is the effectiveness of insulation I have in my cabinet.

Top: the temperature at the very top of the cabinet.  I was interested to see how much the temperature changed between top and bottom of the cabinet.

Considerations when viewing graphs

You will see the hysterysis “shift” higher and lower at several points.  This is where I have adjusted the temperature for the thermostat to compensate for wort temps.

To view a time section in any graph, click and drag left or right and the selected time period will be displayed in the full width of the graph.

The graph page should resize (width wise at least) to your browser.  Please let me know if it doesnt (provide browser and screen res you are using).  For whatever reason, the graphs are not viewable on iPhones (well, mine at least, its a 3G).

This dataset is not what you would call a completely controlled experiment however there are some interesting findings.  For instance, when the shed ambient temp was lower but close to my thermostat setting of 22 degrees (say 18 degrees), the wort seemed to gradually drop in temperature.  when the shed ambient temp was lower but further away (like 10 degrees) the wort seemed to increase gradually in temperature. It also tells me that maintaining cabinet ambient temp is not enough to keep a strictly accurate wort temp.  More sophisticated methods might be required to achieve this.  More controlled tests need to be performed but this is a very good starting point.  I am really quite pleased with the information I have been able to gather.

Where to from here?

The upshot is that for the duration of the brew I was able to remotely access my home server to see what the latest readings were and therefore monitor my brew 24/7 without having to go into the shed.  I created a simple page on my server that provided details of all the required services that need to be running to log the temps, when the temps were last read and what the temps were and all accessible through my iPhone.  I found this information invaluable and needless to say it impressed my friends, particularly the home brewing ones!

In time we intend to provide all the necessary details on how you can set this system up for yourself with minimal outlay.  All the software we have used for this project is open source and therefore free – that was one of our main priorities.  However, we do encourage you to donate to the various groups that provide their software for free as without the thousands of hours that have been dedicated to developing all the various software packages we have used (not to mention the Ubuntu operating system) this post would never have been written.

Our end goal is to provide a website where you can login and monitor and maintain your brews remotely.  The idea is that once you have an account at www.fermentinator.com you can enter these details into our software on your home server and your data will be “pushed” from your home server to the website.  Opening up your home network to the internet is not difficult to do but its not for the faint hearted.  You need to have a solid understanding of what you are doing and what the implications might be (ie having your home computers hacked).  I have dedicated firewalls, logging and security systems in place to protect my home network.  We make no recommendations about remotely accessing your own home server, do so at your peril.

Now, if you partner this work with the work that Andrew has done on building a heat sink and peltier module (my next project), introduce some new computer hardware to control the switching on and off of the peltier modules (USB Relay devices) and pretty much all my issues with ambient temps and current weather patterns will disappear!

You can find us on Facebook and Twitter, link up to PimpMyBrew.com and as new articles are completed you will be advised via these streams.

We are going to be doing a simple join in two pieces of wire that will end up looking like this.

Index
Step 1 – Get the right tools
Step 2 – Strip the insulation off the wire
Step 3 – Twist the strands
Step 4 – Set up your soldering iron
Step 5 – Tin the wire
Step 6 – Remember your heat shrink
Step 7 – Join the wires
Step 8 – Apply the heat shrink

Tools Required
Soldering Iron
Solder
Side Cutters
Heat Shrink

Parts List
2 pieces of wire to join

Step 1 – Get the right tools
Having the right tools will greatly help your soldering ability. The absolute minimum necessary here is a soldering iron, solder and some side cutters.

They type of soldering iron can be varied, from the cheap plug in electric model that I have here to a butane gas portable iron, or even a professional soldering station. Whatever the iron type, the procedure is always the same.

Step 2 – Strip the insulation off the wire
In order to solder the two wires together, you need access to the strands of wire. To do this strip the insulation off the end of both pieces to be joined. There are fancy tools to achieve this, I couldnt find mine, but you simply use some side cutters. With pressure on the wire, but not enough to cut it, pull the wire through the cutters to strip the insulation. You hold the cutters as though you are going to cut off about 1cm from the end of the wire, and pull the cutters away from their position.

You are left with a section of bare wire.

Step 3 – Twist the strands
No image for this step, but it looks just like the one above.
Grab the wire between thumb and forefinger and twist the individual strands into one piece.

Do this for both pieces of wire.

Step 4 – Set up your soldering iron
Get your soldering iron ready by plugging it in and wait for it to get up to temperature.
When this is done, you want to make sire that the tip is ready to use and tinned.
It might be handy to have a small piece of wet sponge that you can wipe the end of the iron on. usually you can just keep the sponge in a small dish or saucer with a little water then draw the iron over the top of the sponge for a quick clean.

You should see a tip like this.

Step 5 – Tin the wire
The easiest way to solder joins is to ensure that both piece to join have been tinned, which is applying a small amount of solder to each work piece.

Lay the wire on to the soldering iron tip until it gets hot, then touch some solder to the bare wire. This ensures a good contact between the solder and wire as the wire is hot enough.

Do this to both pieces.

NOTE: If you are soldering something that is sensitive to heat, ensure that you dot over heat it, by either using a heat sink on that device, or just using the minimum time needed to melt the solder.

Step 6 – Remember your heat shrink
When you are joining wire or assembling components, you dont want the bare wire from your joins to ome into contact with other wire or components otherwise you are likely to short something out or destroy it.
To overcome this, we use heat shrink. It is a plastic like insulator that shrinks to about half its size when heat is applied.

Cut a piece of heat shrink that is big enough to cover your join and is of a size that will shrink down enough to stay in place when shrunk. Forgetting to put the heat shrink in place BEFORE you make the join will mean a frustrating chore of undoing the join to put the heat shrink in place.

Step 7 – Join the wires
Hold the two wires to be joined in close proximity in the same location that they will be when joined, and apply a fast, light touch of the soldering iron until the solder on both wires have melted and flowed into one piece.

Hold the work steady after you withdraw the soldering iron for the solder to set.

Step 8 – Apply the heat shrink
Slide the heat shrink into place and shrink it with the soldering iron.

Your soldering job is now complete.

These techniques apply for any job really, and are well worth learning and practicing to get proficient at.

Below you can see what we are building today.

More after the break

Index
Step 1 – Cut hole in cabinet
Step 2 – Fit the aluminium bar
Step 3 – Mark and drill the holes
Step 4 – Finished

Tools Required
Electric hand drill
Jigsaw
Screwdriver

Parts List
Assembled aluminium block from part 2
8 x self tapping screws with flat head

Step 1 – Cut hole in cabinet
Lay the aluminium bar on to the cabinet where you want the peltier unit and mark out the hole to cut. You will want to drill a hole to start off the jigsaw cut.
Make sure that you cut the hole a couple of mm larger than the aluminium bar to account for the plastic extrusion.

Make sure to cut small rebates to take into account the bolt heads. You dont have to be too accurate, just make them a little bigger for an easy fit.

Step 2 – Fit the aluminium bar
Simply push the aluminium bar into the hole that you have just cut. It should be a comfortable fit, not too tight and not too sloppy. If it is too sloppy you might be losing heat or cold as there wont be any insulation.

Step 3 – Mark and drill the holes
All we are aiming to do here is to securely fasten the unit in place. The number of screws is up to the installer, however I used 8.

Step 4 – Screw into place
Screw the unit into place with the self tapper screws and you are now complete.

Stay tuned for our next installment when we assemble the peltier unit.

We have chosen to use a plastic extrusion so that the heat and cold from the bar can be isolated from the MDF construction of the cabinet. This should serve two purposes.

1. Keep heat/cold loss to the outside to a minimum (remember that the bar is what transfers the heat/cold inside the cabinet)
2. Reduce the likelihood of any condensation coming into contact with the MDF.

Here is what we are going to be building today.

More after the break

Index
Step 1 – Aluminium Bar
Step 2 – Plastic extrusion cut to length
Step 3 – Trim extrusion to length
Step 4 – File away the rough edges
Step 5 – Mark out location of holes
Step 6 – Drill clearance holes
Step 7 – Mark hole locations on the bar
Step 8 – Drill the holes
Step 9 – Clean as you go
Step 10 – Tap the holes
Step 11 – Attach the extrusion
Step 12 – Finished piece

Tools Required
Drill Press (or hand drill)
M4 Tap + Drill set
Tap handle
Screwdriver
File
Saw or other method to cut plastic extrusion
Tin Snips

Parts List
1 x Aluminium block from part 1
8 x M4 x 10mm Nylon Bolts
4 x 100mm 25mmx25mm right angle plastic extrusion

Step 1 – Aluminium Bar
This is the aluminium bar that we made in the last step, stripped of everything that we previously attached.

Step 2 – Plastic extrusion cut to length
I chose a 25mm x 25mm plastic extrusion as it was a common size, easy to get and seemed to be adequate for the job. This extrusion will be secured to the aluminium bar to hold it to the fermentation cabinet.
You need 4 pieces that are 100mm long. Cut them with a saw or use tin snips to make them the right size. Tin snips isnt ideal as it will leave a mark on the cut face, but use what you have easy access to. I used a compound miter saw.

Step 3 – Trim extrusion to length
2 of the extrusion pieces need to have 25mm removed from one face so that they do not overlap when assembled. Use your tin snips to cut away the piece.

Step 4 – File away the rough edges
As the heading says, take your file, and smooth out any rough edges left by trimming the extrusion.

Step 5 – Mark out location of holes
We are going to attach the extrusion to the aluminium bar with M4 Nylon bolts so that there is no chance of transferring the heat or cold or condensation to the cabinet. First start with marking out where you want to drill the holes.

Step 6 – Drill clearance holes
Now that the location of the holes are marked, drill a hole of suitable size to allow the M4 bolt to pass through.

Step 7 – Mark hole locations on the bar
You can now mark out where you want the extrusion to fit onto the bar, and locate where the threaded holes need to go.

Step 8 – Drill the holes
Drill the holes in the aluminium bar at your marked locations.

Step 9 – Clean as you go
I thought that I would mention this step, even though it isnt technically a step in this process, you should get into the habit of having a clean work space. That means cleaning up all the swarf (metal filings) as you go.
A clean work space is a safe work space and you will find it a much easier chore if it is done a little at a ltime rather than a big clean at the end.

Step 10 – Tap the holes
Now that all the holes are drilled, you can use your M4 tap and cut a thread in each of the 8 holes.

TIP: be careful with the tap. Make sure that you are only cutting a few turns at a time before backing off the tap and cleaning the swarf out of the hole. Trying to cut too much in one go will lead to the tap sticking and in all likelihood you will end up breaking it.

Step 11 – Attach the extrusion
Take your nylon bolts and piece by piece attach the extrusion. Be careful not to over tighten the bolts as the head is easy to strip on nylon bolts.

Step 12 – Finished piece
The bar is now finished with each of the 4 extrusion pieces fitted.
Note how I left 5mm gap at the top, just to allow myself some leeway for the heat sinks and so that they had some air under them.

NOTE: You can see that I have chosen to use square cut corners instead of 45 degree miters.
There is no reason for this other than it was easier to measure and my compound miter saw is difficult to get accurate cuts at this scale as the blade is 3mm thick.
If you want to go with 45 degree cut corners, then it will work just as well. You will need to adjust the lengths however so that you have 2 x 100mm lengths and 2 x 150mm.

Here is a mockup of the cabinet with the heating/cooling module installed.

Here is a mockup of what we are going to be building today.
This is a module that contains two Thermal Electric Coolers (Peltiers) that when power is applied to them one side gets hot, the other gets cold. This is the basis for the temperature control in the fermentation cabinet.

UPDATE: After building this module it became apparent that the heat sinks that I used were not big enough to keep the external side of the peltiers cool enough to make the internal side of the heat sink cool enough to be effective. In a previous version I used a much bigger more expensive external heat sink, and that worked fine.
In this version however I want the performance to be much higher, so I have decided to move on to water cooling with a custom built water block to cover the two peltiers in one. Please see a new post coming next week outlining the new water cooling system.

Index
Step 1 – Computer Heat Sink
Step 2 – Aluminium Block
Step 3 – Test fit
Step 4 – Line up for positioning
Step 5 – Remove Heat Sink Fan
Step 6 – Mark it out and drill
Step 7 – Drill the fins
Step 8 – Drill and tap the block
Step 9 – Put it together
Step 10 – Example
Step 11 – Repeat for other heat sink
Step 12 – Attach bottom heat sinks

Tools Required
Drill Press (or hand drill)
M3 Tap + Drill set
M5 Tap + Drill set
Tap handle
Screwdriver

Parts List
1 x 50mm x 50mm x 100mm Aluminium block
4 x Computer Heat Sinks and Fans
2 x 40mm x 40mm Peltiers (90 watt)
8 x M3 x 25mm Nylon Bolts
2 x M5 x 15mm steel bolts

Step 1 – Computer Heat Sink
Source some heat sinks and fans from your local computer store, or better still, your local second hand computer market. You dont need anything flash here, just an ordinary computer processor heat sink and fan. The design that I am currently pursuing requires 4 of each. Here is one of the four that I picked up for $5 each. (click to embiggen)

Click through the jump to read the whole work log.

Step 2 – Aluminium Block
You are going to need a big block of something to carry the heat/cold through your cabinet and to the inside. Obviously copper would be ideal, however not wanting to take out a second mortgage on my house I settled for Aluminum.

Step 3 – Test fit
Test fit your heat sinks on the aluminum block to get your spacings right. Take special note of any gaps that you will need to leave for the fan housings or overhanging sections of heat sink.

Step 4 – Line up for positioning
Now that you know where the heat sinks should be, work out the spacings for one of them. At this step you have to take into account the size of the peltier, at 40mm x 40mm usually, and also where the bolts are going to go. Of course, try to get them as far from the edges of the block as you can.

Step 5 – Remove Heat Sink Fan
Now, remove the fan from the heat sink as we are going to need to get at those fins underneath the fan.

Step 6 – Mark it out and drill

Mark the hole location on the underside of the heat sink and drill a hole right through that is big enough to allow for the appropriate clearance for your bolts of choice.

Step 7 – Drill the fins
Now, flip the heat sink over and drill a pilot hole through the heat sink fins. Once you have done this, up the drill size to one that gives you clearance for the bolt head, but dont go all the way through, leave quite a bit of the heat sink material.

Step 8 – Drill and tap the block
Now you have the heat sink done, you can pop it onto the top of the aluminum block and mark the locations of the holes on the block. Once marked, drill the holes to an appropriate depth. I drilled them about 30mm. When these holes are drilled, tap them with an appropriate thread tap for the bolts that you are using

Step 9 – Put it together
Now fit the heat sink to the block with your bolts, making sure that you have them at the correct depth so that they are not too long. This is as good a point as any to mention my bolt choice. Because the peltier is 40mm x 40mm and the Aluminum block is 50mm x 100mm, there is 5mm spare on each side.
I chose an M3 bolt thinking that 2mm would be enough material on the side of the block to hold the heat sink and bolt. We are putting the peltiers on the outside of the cabinet so that the waste heat or cold can escape without affecting the internal temperature.

The peltier is sandwiched between the heat sink and the Aluminum bar, so thermally joining the heat sink to the bar is a bad idea. This is because one side of the peltier is hot while the other is cold and we would be in effect joining the two together with a metal bolt that will transfer that heat / cold to the other surface. Because of this I have chosen to use nylon bolts that wont conduct the heat or cold. They are surprisingly strong in the smaller M3 size and should do the job quite nicely.

Step 10 – Example
Now that you have the heat sink fitted to the block and the peltier sandwiched in between, it should look something like this.

I haven’t mentioned the fitting of the peltier module here, and don’t have any images of that just yet, but it is a very simple process. You just need to treat a peltier like a computer processor and use a heat sink compound.

The following step outlines what you need to do to fit the peltiers to the bar, however dont do this just yet as we will be disassembling the module prior to the next step.

Ensure that all the work that you have been doing has not damaged the Aluminum bar nor the heat sink surface, and clean them up as best you can. Put a good amount of heat sink compound on the peltier and push it into position on the bar. Repeat on the top of the peltier and push the heat sink on. What you are looking to do here is to have an even thin coating on all mating surfaces.

This will help the heat or cold pass from peltier to heat sink or Aluminum bar. You cant really get this wrong as long as you have covered the peltier on both sides. Too much compound wont be too much of an issue, but it does take a bit of washing to get off your hands or clothes, so don’t go overboard. The other thing to take in mind when fitting the peltier is that they are ceramic and you can indeed break them if you are too rough or you tighten the bolts too tight. Again, no real tips here, just dont go gung ho.

Step 11 – Repeat for other heat sink
Now rinse and repeat for the other half of the block. It will look something like this with the fans fitted (don’t fit them yet though)

Step 12 – Attach bottom heat sinks
Flip the lot over and start on the bottom, however we are going to cheat on the base that will be inside the cabinet. There are no peltiers going inside so you are just attaching the heat sink to the aluminum block, and as this will be in side and need to be assembled in there, we are just going to use one big M5 steel bolt in each heat sink.

Use the same process as before, drill a hole through from the bottom of the heat sink that is the correct size for the bolt, but not the head, to pass through, then from the top drill a hole big enough for the bolt head to make it through the fins, but not the base. Position this on the block to match the positioning of the top heat sinks, then drill and tap the hole in the block.
When you have those two holes drilled and tapped you can test fit the bottom heat sinks to the bar. You will have a finished product that looks like the below photo.

That concludes this tutorial, you now have the assembled heating and cooling module. Next up will be fitting a shroud around the bar to protect the MDF cabinet and to allow you to fix the module in place. After we have done that step we will be fitting the module into the cabinet and completing our wiring.

I have been busying myself with home brewing of beers, ciders and ginger beers. Home brewing is a great hobby that gives you great control over what you make. Flavours can be tweaked, styles can be modified.

On the whole it is a very simple process and certainly not one to be afraid of.

In days gone by, home brew was something that your neighbour or father in law did, and the results were never anything to write home about. They would spend nights in their shed or laundry concocting and maintaining their brew and spend the days roaming the neighbourhood and harassing their friends to collect bottles.

Times have certainly changed now. Coopers have seriously commercialised the worldwide home brewing industry and are the biggest home brew manufacturer in the world now. They product some fantastic kits and sell everything that you need.

A starter kit will set you back $80 and contain everything that you need to produce an excellent Coopers Lager.

I digress.

In my short time brewing I have discovered something that not all home brewers stumble upon. One of the most important factors of producing a GOOD home brew is ensuring that the first fermentaion cycle is done at a controlled temerature in the right range.

I have had some cracking results with beers brewed in my garage, but that was while the ambient temperatures were higher, and a bit more consistant. Now that we are in winter, the Sydney temps are varying a bit and where I live it gets as low as 3 or 4 decrees C overnight and as high as 20-24 during the day.

This is causing me issues.

My latest batch is no exception. The thermometer tells me that the maximum temp for the current brew was 21 deg C and the low was 16 deg c. This is going to be reflected in the taste I am sure. (ideal is 22 deg c)

So, what is a brewer to do to fix this? I am building a fermentation cabinet. Big enough to hold two carboys and lined with insulating foam, it will be able to level out the temp differences. However of course I am not leaving it at that. I have a peltier cooler and a temperature controller and am going to create a franken-heater-cooler cabinet that will hold a temperature. It will heat to get the right temp if the ambient temp is lower that the set temp and it will cool when the ambient is higher.

I am still collecting the parts at the moment, so expect updates in July as to how it is going, however my testing last weekend allowed me to refrigerate a cardboard box that was not insulated down to 6 degrees c from the ambient of 19 degrees c, and heat up to about 35 degrees c.

This is going to be an interesting project and I am yet to find any reference online about something similar.

Yes, yes you can.

In my previous post I outlined what I was hoping to acheive with this project. I have now completed the mark II revision and will soon have some results to taste.

The process was reasonably simple with a little electronic magic.

The first part of the project was to build a cabinet to hold the fermentation carboy. This is a 30 litre container that is used to hold the beer mixture while the yeast chows down on the fermentable sugars to produce alcohol. The cabinet is basically just a 6mm MDF box with another 6mm MDF box a little smaller on the inside. This creates a 1 inch void on each side that I filled with marine expanding foam.

Voila! A big ice-box basically.

That was the easy part.
OK onto the electronics and hardware.
In order to control the temperature, you are going to need two components.
1. a method to control the temperature
2. a method to affect change on the temperature

Part 1 was reasonably simple in theory, however in practice it wasnt so easy to acheive. I purchased 2 controllers before I found one that worked as I wanted, so that was 3 all up.
The first one that i got was a kit and allowed me to control a heater and a cooler and to acheive a pre-set temperature, however it has a few serious drawbacks. The first was that while there some degree of hysteresis (the ability to have a dead zone) the unit basically could only go from heating to cooling or cooling to heating. There was no zone where if the pre-set temperature was reached where the unit would turn off the heater or cooler.
This is a bigger deal than it seems.
You dont want your system to drive up or down to the required temperature and then when it gets there to drive back the other way. basically it would heat until it reached the set temp, then cool until it wasnt at the set temp then repeat the process adnausium.
This is not ver efficient.
Secondly, there was no easy way to set the temperature. It had a potentiometer and you dialed up a resistance basically. Not very user friendly at all.

These two things made this controller unusable for this application.

The second false start that I had at the controller involded a PID based digital controller. This was very close to what I needed however in excitement to buy something I didnt think hard enough about what i was buying. This meant that I ended up with a controller that while it could handle heating and cooling circuits, you had to choise which one you were going to use. it couldnt control heating and cooling at the same time.

Third time is a charm!
I now have the right controller and it is a beauty. You dial up a temp that you want to maintain and it switches one of two relays based on if it needs to heat or cool to get to that temp. Hysteresis is varyable for either the heating or cooling side. I have it set to 0.2 degrees C either side of the set temp. This means that if your set temp is 10 degrees C and the item that you are measuing is at 10.0 deg C then nothing is turned on. If the item gets to 10.2 deg C then the cooler is engaged until the temp gets down to 10.0 deg C again.  The reverse is also true.

So, that is the controller taken care of, but how am I going to heat or cool?
For this I decided to use a peltier device.
A peltier is a solid state device that heats on one side and cools on the other when a voltage is applied. Simply reverse the polarith and the heating and cooling sides reverse as well.

With a big computer heatsink on the top of it, and a 50mm x 50mm x 100mm aluminium bar on the bottom of it and then another computer heatsink on the bottom of that I fashioned a basic heating and cooling element.

So, there is the active hardware side taken care of.

From here on in it was relatively simple with the exception of a couple of electronic tricks.
I had to be able to handle reversing the polarity of the power to the peltier. In order to do this i needed to create a little bit of a franken-relay situation due to the way that the temp controller was made.

The controller uses a common earth on the output relay, so you only have 3 terminals. The heating circuit joins terminal 1 and 2, while cooling joins terminal 1 and 3. Unfortunately that meant that I had to make my own way of powering the peltier and ended up using the controller to through 2 double through double pole relays. In this way the common ground didnt matter and I used the relays to swap the polarity.

The tricky bit was being able to power the computer fans as they have a set polarity that they work with so that the blads only spin in one direction. This one was easy to fix as well as it only meant using a bridge rectifier to rectify the output to the peltier so that it was always in one polarity.

OK so does it work?

I have had a lot of feedback from variuos forums that the peltier wont work. Well, i can tell you that it does.
The first batch that went through the fermentinator was my test batch with a fermentation temp of 22 degrees C. It was heating most of the time as it was winter at that time., and the temps were within 0.2 deg C of 22 degrees C the whole week.

The second batch was a pilsener and it needed a low temp. It spent the first week at 15 degrees C and handled that very very easily, however I decided to go for broke and gave it 10 deg C for the remaining two weeks. It was able to keep up…. just.
When i say just, it was perfectly fine, but the tolerance was increased to 1 degree C. Lowest temp 10.0 deg C, highest 11.1 dec C.

I am happy with that considering that the ambient temps got up to about 26 or 27 degrees C.
Sure, that is not going to be able to cool 23 litres of wort to a consistent 10 deg C when it is 40 deg C ambient, but really, that would be unreasonable.

I can always add another peltier and heatsink module in there as well, that will make it easier.

This is an interesting question that I have found myself asking lately.
I rant the first test through my cabinet with the following conditions.

I used a Coopers ‘kit and kilo’ kit of their Sparkling Ale.
It was mixed as per instructions to make up 23l.
BEFORE pitching the yeast I took 11.5l out into a second carboy.
Yeast was divided and pitched.

One carboy sat on my garage (I mean brewery) bench, while the other went into the fermentation cabinet set at 22 degrees C.

over the week long first fermentation cycle the ambient temperature brew ranged in temp from a low point of 16 degrees to a high point of 28 degrees C, while the fermentation cabinet brew has a low point of 21.8 degrees C and a high point of 22.2 degrees C.

Obviously the theory goes that if the temp is uber consistent then the yeasties will have a good regular chow down, whereas if the temp varies then they will eat a bit, rest up a bit, then chow down vigurously.

Note, I did say theory there!

So, 1 week first ferment, then bottled. I numbered the bottles as they were drawn off from the carboy so that I know where in the batch each bottle is from. Into the garage brewery cupboard for 4 weeks and we are ready for a blind taste test.

Bottle number one fermentinator and number one ambient are chilled for a day then we are ready for tasting.

two taste testers both handed an A and a B glass and both were unanimous that one beer was far superior to the other.
The only issue was that the superior beer was the ambient temp fermented one.

So what went wrong?
Was that $400 or so down the drain on fermentation temperature control?

Well, I dont think that anything went wrong as such as there was absolutely nothing wrong with the fermentinator batch, just that the ambient fermented batch was much better. That tells me that the fermentination cabinet could churn out that same beer time and time again, while I may never get the same temperature ranges for the ambient brewed beer.

I am not actually upset at the results. Well I have 10 or so bottles of a really fantastic beer to dring and the same of a pretty good beer to drink 

Where the fermentinator comes into its own though is Lagers. The Pilsener that I now have in secondary in the fridge could never have been first fermented without the fermentation temperature control cabinet. It sat for 1 week at 15 deg and 2 weeks at 10 deg C while ambient temps got as high as 30 deg on one occasion.

That experiment will take to Christmas to come to fruition but I will continue to use the cabinet for all the brews that I put up from now on, making for easily repeatable results.

Stay tuned for the next installment on how I made a 4 channel temp logger with internet based graphing so that I can check the Ambient, Carboy, Internal heatsink and External heatsink temps from anywhere with an internet connection…..