Controller for RIMS – Man or Machine?

The idea behind a RIMS system is the heat is equally distributed around in the mash by the running wort driven by the pump.  But something needs to control the heat (hot-plate or immension heater), either man or  machine. If man one must have a keen eye on the process and stay near to the mashing process. Machine range from controlled overshoot systems till PID-system with very low fluctuation of the temperature!

One thing to notice for both man and machine, is the strike water temperature is important and one should calculate (taking the amount of malt and water into account) what the strike water should be for the desired mashing temperature!

Man – Induction stove

The most basic way of controlling temperature is to use you own mind and try foreseen when to heat or turn heat down. On Induction stove it is not that complicated and with the high resolution of many  induction stoves, you can get very near to have a steady level especially if you have the pump running steady and ensure some kind of over-spill system. As most of the starch transformation is done in 30mins it does not matter if temperature raise or lower  by 1´C during an hour. The “man” way if ofcouse the cheapest, but you need to keep a keen eye on the mashing process and hence take time away. But might be the way to see if RIMS is anything for you.

Machine – STC1000

The nest step away from man is to make use of an temperature controller able of handling the load of 10A (if in 230v countries equaling 2300W). This will control the heater and give some overshoot as there is no intelligence  build into it. It simply close off when the set temperature is reached. As many have either STC1000 or similarly form there fermentation chambers, this is a fast way to go for a “one set point mashing controller”. To limited the overshoot, one could turn down the hot-plate output when set point is nearing/reached as this will limited the energy and further overshoot. I got around 2-3`C overshoot when reaching set point as a lot energy is stored in the iron of he hot-plate, but afterwards during mashing it seems to be 1.5´C. If turning down the hot-plate outpoint it was limited a bit more! So if I set it at 65´C it would stay between 64-67`C on a STC1000 with a likely geometric mean of 66`C. An STC1000 with cords and plugs can be done for 15EUR.


Intelligent PID controller – CraftbeerPi

To get the best resolution on the temperature of the mashing an intelligent system is needed, a so called PID controller. It is likely possible to buy semi final system cheap off Ebay, but I choose to build my own webbased CraftbeerPi controller based on RaspberryPi, 2xSSR, temperature probe, etc. This limited the overshot and the error till +/- 0.5´C.


For more on parts and how to build please take a look at:



What you need for “Control-box (CraftBeerPi) + hot plate”:

  • Hot plate, used, I paid 7 EUR
  • Rapsberry PI Zero with pins soldered on and WiFi version = 25 EUR
  • SD card, 5 EUR
  • DS1820 Waterproof, 1 EUR, China, Ebay
  •  Thermowell stainless steel, 10 EUR
  • Some Jumper Cables, 0.5 EUR, China, Ebay
  • 1 x 4.7k Ohm Resistor, 0.1 EUR, China, Ebay
  • 2 SSR, 2×5 EUR, China, Ebay
  • Ipad charger (2A to get stabile current), free
  • 3xPlugs, cord, 5 EUR

In all around 55-65 EUR!

If you buy an older (used) Rapsberry (Zero) not holding pins nor being WiFi version you can safe 10-15 EUR there too. But you might need an Wifi adaptor and do some soldering then!