Friday, July 11, 2014

Designing a Brew Chamber Controller (Part 1)

This is the first in a series on my design of a brew chamber controller.  I'll explain as we go along why we are using a certain item or doing something a certain way but not get into details; for instance we'll discuss why temperature control is important when brewing beer but not how to brew beer.

So just what is a Brew Chamber and why do we need a controller for it?

A brew chamber is a temperature controlled environment that is used to brew beer.  When yeast are fermenting they need a few things, water, sugar, nutrients and a temperature that permits a controlled ferment.  If the temperature is too hot the ferment runs too fast and certain off flavors can be imparted into the final product, whether it's beer, wine or saki. On the other hand if the temperature is too cold the yeast will struggle and yet again impart off flavors and also take longer to ferment or not ferment at all.

Different strains of yeast have different temperature ranges for optimum brewing conditions. Also different styles of beer and wine depend on certain temperature ranges.  So we'll have to track these ranges in tables in the control program.  We'll discuss in detail on this later in the design process.  Also we need to consider that when yeast are fermenting they generate some heat of their own, so the temperature of the liquid going through the fermentation process will be warmer than the ambient air temperature inside the brew chamber. On smaller scale systems like 6.5 gallon systems this is not much of an issue but on larger scale systems this is a major problem that needs to be addressed with additional cooling requirements.

Now knowing this information we can see we'll need a controller (a fancy thermostat) to turn on the cooling or heating devices depending on the brew chamber temperature, or better yet, the temperature of the actual liquid we are fermenting.

Why do we need to heat the chamber?  This feature may be optional if the brew chamber is located in a room that is always warmer than the optimum fermentation temperature.  If this is the case then we can omit the heating element (pun intended) of the brew chamber controller, or just have the controller ignore it. But if you plan on keeping the brew chamber in an unheated garage or shed where the temperatures may drop below optimum fermentation temperatures then a heater should be used.

OK, so we now know what a brew chamber is and why we need to control the temperature of the fermentation, what can we use for a brew chamber?

An insulated container large enough to house the fermentation vessel.  Most home brewers use 6.5 gallon fermentation vessels so the brew chamber will need to be large enough to hold the fermentation vessel and enough height to also allow room for the rubber bung and airlock.  The rubber bung and air lock are used to keep oxygen out of the fermentation vessel while letting the carbon dioxide (a by product of fermentation) out of the vessel, or we may have an explosion.  The fermentation vessel wouldn't have to be airtight but we'd have no way of monitoring CO2 off gassing to determine fermentation rate or if fermentation is complete.

So we can build our own insulated chamber out of plywood and Styrofoam insulation and that would work but how are we going to heat and cool it? 

To heat the brew chamber something simple as a heating pad (for sore muscles) or an incandescent light bulb can be used for the heat source but it takes something more to keep the brew chamber cool. We're talking between 60 and 70 degrees Fahrenheit for most fermentations and even cooler for lager or cold crashing. Cold crashing is a method used to quickly drop suspended yeast and make the final product more clear. Largering and cold crashing require a freezer since most refrigerators don't get cold enough for this purpose or would struggle or use more energy if they could get this cold.

You could hack together your own refrigerator or freezer unit to put in your brew chamber but there is a much neater solution.

You could obtain a refrigerator or freezer, either used or new.  Some things to consider when looking for a fridge or freezer. The size has to be at least large enough to house the fermentation vessel. If you are going to be using a pressurized kegging system to carbonate beer then the brew chamber needs to be large enough to house both the brew chamber and however many kegs you want to carbonate at a time.  The CO2 tank used to pressurize the kegs can be located outside the brew chamber. The pressure hoses will be routed through holes in the walls of the brew chamber.

Yes, you are going to have to cut/drill holes in the fridge or freezer so if you are not comfortable doing that on an expensive new unit then start looking for used one.

If you want to do continuous brewing then you will need room for an additional fermentation vessel to age the previous batch while the next batch is fermenting. A second brew/aging chamber is also an option if you are a serious home brewer. That way you could have 2 batches brewing in one chamber and more batches aging, lagering, or kegging in another.

I'm not a serious home brewer so I'll just be using one chamber to process a single batch of beer through it's cycle then keg it and start another batch while drinking the previous while still having the options to cold crash and lager if needed.

The other thing you will have to watch out for when searching for a fridge or freezer is that if purchasing an upright unit the shelves will have to be removable.  Some freezers have the freezing elements built into the shelves and they can not be removed.  Most fridges have adjustable shelves that can be removed however the bottom of the fridge may need a plywood shelf at the bottom to provide a strong level surface to hold 6 gallons of fermenting liquid and 5 to 10 gallons of pressurized kegs.

Considering all the above I'm thinking of a chest type freezer with a 1/2" to 3/4" plywood insert at the bottom for extra support so the fermentation vessel and kegs don't damage the freezer's internal walls.

So why use the BBB as a controller for this project when there are complete digital temperature controllers for less than the cost of the BBB alone? If all you want is a simple manual way to control the low and high temperatures in the brew chamber then that is the best way to go and I'd recommend that over the BBB.  But since I'm a bit of a geek I wanted more features in my controller.

Things like (in no particular order):
  1. Remote/internet access (private access)
  2. Local LCD touchscreen GUI
  3. Web page system status w/ webcam snapshots (public access)
  4. Web cam to monitor the inside of the chamber without opening the brew chamber lid
  5. Compare/chart chamber and vessel temperature differential
  6. Automated brew process
    • warmer start temperature to quickly optimize yeast colony size
    • gradual cooling to optimum fermentation temperatures
    • cold crash cycle when ferment is complete (requires a freezer)
    • lager cycle if needed for style of beer (requires a freezer)
  7. Select different brew programs depending on style of beer/wine and yeast used
  8. CO2 off gassing monitoring to determine:
    • rate of fermentation
    • completion of fermentation cycle
  9. Monitor keg pressures
  10. Monitor how much power the brew chamber is using
  11. Monitor external temperature
  12. Monitor humidity (?)
  13. Something to do in my "me time"
  14. Something to share with the maker/hacker community
Most of these things you can't do with the simple digital temperature controller sold online.

So there is the start of this project.  Stay tuned for additional posts during the design phase.


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