Building A Recirculating Infusion Mash System For Your Brewing Pleasure

If you’re into all-grain brewing a little automation goes a long way. [Tom Hargrave] had his eye on a Recirculating Infusion Mash System (RIMS) but the price tag kept him from pulling the trigger. Recently he bit the bullet and built his own small and inexpensive RIMS for use with the 10 gallon cooler he uses as a mash tun.

Mashing is the part of brewing process that collects sugars from the milled grains. Water needs to move through the grain mash and should be kept within a narrow temperature window. This RIMS hardware does that automatically by combining a pump, the heating element from an electric water heater, and a temperature sensor. The wooden disc fits on the top of the mash tun and tubing lets the pump move the liquids as needed. The one thing missing from this build is the PID controller to automate the process. After the break we’ve embedded a video from a separate project that shows off how the PID control would work with a system like this one.

If you’re into automated home brewing you’ll also like this mini-batch brewing setup.

28 thoughts on “Building A Recirculating Infusion Mash System For Your Brewing Pleasure

  1. just a random question wouldn’t the grain clog the intake if the valve is located at the bottom of the mash tank, you might want to reverse the connections so it pumps the water from the bottom valve up, unless of course you already thought of this and have a wide enough gage pump that will move the grain through the tubing, and i just want to say i’m not trying to be that jerk thats like “you did it wrong!” i was just wondering and offering possibly helpful input : )

    1. The grain bed sits on top of a grating so that only the wort is in the sump at the bottom. Reverse flow seems like a good plan to me, but at the end it’s gravity flow to get the wort out, so you’ll still need a way to strain the liquid. Read up on “lautering” and see if you get some good ideas.

  2. I figured that the temperature of the wort would have been monitored before the heating element as not to overshoot the desired temperature. This is way more complicated than what dad would do. A can of malt syrup from the supermarket sugar water. No brewer yeast when there was yeast in mom’s cabinets, as I recall. Let it work in a 35 G crock covered with a bath towel until the hydrometer said time to bottle.

    1. A can of malt syrup from the supermarket sugar water. No brewer yeast when there was yeast in mom’s cabinets, as I recall. Let it work in a 35 G crock covered with a bath towel until the hydrometer said time to bottle.


      What? I don’t even…

      I dearly hope you have advanced beyond your father’s methods. A well brewed beer is so much more than alcohol content.

    1. My though process was monitoring the temperature of the fluid as it entered the tube would be a better indicator of the temperature being maintained in the vessel Perhaps I should stop thinking :), because this is more involved home brew process than any I have witnessed.

      1. It’s critical to always measure temp post-heating. Otherwise, the element could essentially be boiling the wort (and denaturing the enzymes) while the RIMS input temp is still low.

        Reliable PID operaton requires input change response as quickly as possible or overshoot & instability can occur.

  3. The problem with all RIMS designs is that they can’t deliver on the original promise: you can’t do stepped mashes in a realistic time without overheating the wort as it passes by the heater.
    Either you pump a crazy speeds (which requires wort that is too thin), or you heat slowly (which means you spend too long reaching the next temperature stage)
    So basically, they are a really high tech replacement for good insulation.

    1. Well, yes and no. With a properly designed RIMS tube the water flow past the element is fast without having to pump massive volumes of wurt. But all of the designs I saw on the net used pipe that was way too large & this causes the water to slow down too much.

      The two designs I saw while researching this project used 2″ & 2-1/2″ pipe. The cross section of 2″ pipe is 3.14 sq in while the cross section of a 2-1/2″ pipe is 4.9 sq in. My RIMS tube was designed with 1-1/2″ pipe which has a cross section of only 1.77 sq in.

      This makes a huge difference in water speed past the element. If I were to use 2″ pipe instead of 1-1/2″ pipe my flow speed past the element would drop to 56% of my original design and if I were to use the 2-1/2″ pipe my flow speed past the element would drop to 36% of my original design!

      1. Another way to look at this is – at 7 GPM (the pump rating), the flow rate past the element after subtracting out the space the element takes up is:

        For 1-1/2″ pipe = 1.46 FPS (Feet Per Second)
        For 2″ pipe = 0.79 FPS
        For 2-1/2″ pipe = 0.50 FPS

  4. Do not take heater on airline.
    A friend is asking me about the reverse of this, the rapid cooling of the brew and all the thermodynamics of this art. Faucet driven cooling coil is the norm.

    1. I am having great success using a heat exchanger from a combo-boiler. That is a boiler that has a gas-liquid exchanger for central heating, and a second liquid-liquid for hot water (the one you want).
      You should check the part has fittings, many just have a press fit flange that makes connecting to a brew setup difficult. Providing there is a reasonable hop filter on the boiler side, there are no blockages.

  5. I built something very similar in the late 90’s using copper. I avoided scorching the wort (sugar water) by having 2 temp probes (inlet/outlet)and monitoring the temps to obtain a max of 3 degrees temp rise as it passed thru the heater. I used a 1k watt 110v heating element in order to use it outside. My controller was a basic stamp with ss relays driving pump speed and heaters. As mentioned above, the step times were slow and required a gas fired lauter tun to augment additional hot water. In the long run though after the joy of watching the bells, whistles and blinkkenlites wore off I went back to manually adjusting my temps but the simple elegance of this build may inspire me to revive my project.

  6. I’ve read that you can run a 240v element off 120, but you will be running at about 75% rated capacity. With the unit described here, has anyone successfully ran this off 120v?

    1. You can but it will be 25% rated capacity, not 75%. This means a 240V 5500 Watt element will onlt produce 1375 Watts of heat. The plus side is 1375 Watts of heat energy is spread across the 5500 Watt element’s marger surface and you will get less scorching.

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