Heating:
Now the system has the ability to heat one or both fermenters. Heating of the fermenters was achieved by converting a rectangular beverage cooler into a water heater of sorts by drilling and inserting a 120v 1500W heating element. A watertight seal was achieved using a rubber gasket as well as silicone caulk. The heating element was controlled initially by an arduino UNO running a PID algorthim (and monitoring the temperature of the bath, which was recirculated using a small submersible pond pump) which opened and closed a SSR. This functionality was then transferred to the due running all of the other functions. Heated and cooled water are supplied and returned in separate piping.
The system to allow for simultaneous heating and chilling of two different beers. Currently, switching between supplying heated or cooled water to the fermenter is done by physically changing the hoses to the pumps. When I can scrounge up enough funds, I will add some 3 way solenoid valves to allow for automated switching. Also in the works is some hard plumbing, replacing the ungainly vinyl tubing.
Monitoring of the water jacket
A design modification of this version is monitoring of the water jacket temperature. By using this temperature to control the action of the pumps (overridden by the temperature of the beer), over and undershoots of the beer were greatly reduced. A downside of this is more frequent activation of the pumps, which can reduce their lifetimes.
So far, the system has fermented 2 beers, a kolsch and a dortmunder lager. The kolsch is currently carbonating, but tastes great. The lager will remain in secondary for another month before being kegged and carbonated.
Here is a picture of the setup before hard plumbing. Note the addition of the hot water reservoir on the right.
An android app, mirroring the functionality of the computer app, has also been created.
