Nerding out on beer – DIY mash temperature control (Travis)

Warning! This post has some numbers, and some technical beer words. Because I’m a nerd for beer.

I’ve had this problem on brew days. I want to maintain a steady mash temperature for long periods of time, but my gas heat source is either too high and the temperature rises, or too low and a breeze blows the flame out. As a result I end up staring at the stove for 60-90 minutes, constantly adjusting a gas valve and re-lighting the stove. It’s a tedious process, but my real concern is recipes are really, really hard to repeat with this method – and I want repeatability.

I saw two solutions: buy some really expensive pre-made controller, or build my own. I chose the latter, and recruited my dad for help. After lots of very confused discussions about the concept of the controller (electric or gas? HERMS or RIMS? how do you convert 3/4″ pipe thread to 5/16″ compression thread? what the #$@# are we doing? that sort of thing), we settled on keeping the RIMS system I had (heated with natural gas), and adding an electrically actuated gas valve controlled by an Arduino processor. When the temperature is too low, the Arduino commands the valve to open, the stove is lit by the pilot light, and it heats up. When the temperature hits the target temperature, the Arduino closes the valve. It’s a simple concept, and took us a painfully long time to iron out. But it’s done!

Last night was the first test run. It’s not exactly pretty… but the result is amazing. I programmed in a 4-stage mash and hit “go”, and it held the temperature within a degree of my targets for 90 minutes. Absolutely repeatable!

Oh, and side-note, last night’s mash gave me 90% conversion efficiency. If that’s not hot, I don’t know what is.

Thanks dad!

Installing the Arduino mash controller

Installing the Arduino mash controller

System at a glance

System at a glance

It's a bit cryptic... but it means the temperature is about as perfect as you can get.

It’s a bit cryptic… but it means the temperature is about as perfect as you can get.

A mess of gas connectors

A mess of gas connectors

The pilot assembly

The pilot assembly


~ by stormcellar on April 25, 2013.

11 Responses to “Nerding out on beer – DIY mash temperature control (Travis)”

  1. Good teamwork!!!!

  2. Awesome!!

  3. nice work sirs! yea repeatability!

  4. Went that well on the first try? That is a miracle itself. GREAT! now onto bigger and better? Did you change the code to add a 4th stage? If it was easy then that pleases me as well. NEXT PROJECT: im working on an automated cat food dispenser. You might like one of these as well.

    • Well… second try… first try was Tuesday when I tried to change the programming, which took me 2 hours, then it was too late to start πŸ™‚
      Yes, added a 4th stage. Piece of cake!

    • I need a cat food dispenser. My cat is getting fat (female, 13 lbs). Bonus if you can keep the food fresher with a vacuum pump.

  5. Hey Travis, I posted earlier but it didn’t take. Looks like a great system. Now you’re going to have to come up and help me with mine. Next phase, add an interlock to your pump to ensure that it’s running prior to the flame kicking on – no scorched wort! Another thing that’s going to be nice about the controller is the flame will be fully on, so no more soot on the side of the mash tun. Happy Brewing!

  6. Oh, forgot to mention, I am impressed with your water resistant housing that protects the controller-clever. πŸ˜‰

  7. Is that why the mash gets so much soot? Never pieced that together!

    That fancy waterproofing was my dad’s work. All I can really claim credit for is the concept and the plumbing. He did the electronics. I did re-program a few lines, so that has to count for a little πŸ™‚

    But, glad you like it! I’d be happy to help you set up something similar. It’d be SO much easier the second time.

    Hope we can brew some time, I’d like to pick your brain a bit again!

  8. Maybe your next project?

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