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.
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
If you really want to analyse whats going on inside your fermentation cabinet temperature-wise you really need a number of temperature sensors attached to a computer program to log temperatures then post the output into easy-to-read graphs.
Continue reading
In the next tutorial it would be best to do some soldering in order to have a good outcome.
Although you can achieve the results without soldering, the joins will be better and you can get a much more professional finish.
We are going to be doing a simple join in two pieces of wire that will end up looking like this.
Part 3 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, now it is time to fit it to our fermentation cabinet.
Below you can see what we are building today.
More after the break
Part 2 of the previous heat sink post.
This time we are taking the aluminium bar from the last step and adding a plastic right angle extrusion to it, that will serve as a bracket to hold the bar onto our fermentation cabinet.
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
This is the first post in a series that is gong to be a step by step guide to building your own temperature controlled fermentation cabinet. At this stage we are not going to go into detail of the actual cabinet as there are many different ways that it could be built, and varying sizes based on your fermentation vessel.
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.
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…..
