Advanced WiFi enabled ESP32 driven power controller and temperature regulator for brewing and distillation boilers. Multiple units can be combined in a master/slave configuration.
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Facebook Idiot: Why would you bother?
Me: It's only a "bother" for somebody who couldn't do it on their best day. I'd rather have nicer things.
After dealing with one cheap Chinese SCR power controller after another I decided to combine one person's email suggestion about building a WiFi enabled PID controller and mash it up with what I had just finished building for Air Still users. PID controllers have their place, but I think they're better suited for 3D printers, fermenters, brew pots, ovens, incubators, etc. The heating element spends more time off than on and that is horribly bad for distilling because there's almost nil upward thermal velocity happening in your boiler.
So I came up with my own controller to overcome all of the shortcomings that I kept running into with others. The Boilermaker has 4 different operating modes.
- Constant Power (similar to an SCR controller, but leaps and bounds better than an SCR controller)
- Temperature Cruise (controlled chaos, fast linear temperature rise with a limited risk of scorching)
- Brewing/Fermentation (PID controller, slow and easy heating with an extreme level of accuracy)
- Cruise Then Brew (Runs mode 2 until the target temperature is reached and then switches to mode 3)
NOTE: Mode 2 is the same temperature control method used in my Airhead upgrade for Air Stills. The progressive temperature feature is also implemented here and can be used in modes 2 and 3. The only difference here is that the Boilermaker doesn't turn off at the end of the progression unless the countdown timer is enabled.
This controller was designed to run a zero-crossing trigger solid state relay utilizing my custom low speed PWM (most effective method for heating elements). My custom low speed PWM works like an SCR controller slowed down to less than 1/1000 the speed and runs heating elements much more effectively. This controller can also be used with an existing PWM controlled SCR board or a voltage controlled SCR board with a PWM to voltage convertor module in the middle.
Heating elements have a slow reaction time, they take time to warm up. An SCR controller divides your AC power sine wave into anywhere from 1000 to 20000 slices and then determines which back-to-back slices are on and which ones are off. Granted, this "works" for heating elements, but it's wasteful and never lets the heating element run at its full potential unless it's at 100%. Anything less just results in a lot of energy wasted by warming up the SCRs instead of the heating element. Exactly what benefit are hot SCRs providing?
In the low speed (0.1 Hz to 1 Hz) PWM that I came up with for the Airhead controller and implemented here, even at 50% power using 0.5 Hz, the heating element runs for 1.25 seconds and rests for 1.25 seconds. Most heating elements run for the full duration of their reaction time. Whereas when using an SCR controller, all heating elements only run for 0.008 seconds 60 times per second. See why a low speed PWM running an SSR is better?
The greatest benefit of this PWM and SSR combination is that it doesn't contribute to premature heating element failure as with the high-speed on/off switching in SCR controllers. SCR phase-angle control generates harmonics (distortions in the AC sine wave) which leads to uneven current distribution, physical vibration, and stress within a heating element. The Boilermaker is actually better for your boiler's longevity!
The Boillermaker uses either a DS18B20 temperature sensor or a thermocouple and a MAX-6675/MAX-31855 amplifier module. If your intention is to only use this controller with a distillation boiler or a meat smoker, then the DS18B20 is perfectly fine since it has an upper temperature limit of 125C/257F. If you need a higher temperature range, you will need to use the Web API call with your web browser to select the MAX-6675/MAX-31855 amplifier combo instead.
The Boilermaker also features a complete Web API for configuration and control, this is how one master unit controls up to 4 slaves. Each of those slaves can also have up to 4 slaves (look at it like an Amway pyramid scheme). This means that these controllers can be added to all kinds of systems out there that allow the use of external commands or API integration of third party devices and services.
The RPi Smart Still system fully supports the Boilermaker in all three operating modes. It can actually run the Boilermaker the same way as an SCR controller or gas valve, but without the need for a stepper motor.
NOTE: The Boilermaker is also handy for turning any cheap electric smoker into one that's a whole lot more reliable and accurate, see the Usage Tips for more information.
