How to Build a Portable RIMS

A RIMS (Recirculating Infusion Mash System) can be used in brewing to maintain as well as increase temperatures during the mash. The idea is that direct heat is applied to the wort if it cools below a set rest temperature or if one wants to reach a higher rest temperature without adding boiling water. I ended up using a 4500W (at 240 V) water heater element to apply direct heat. Lets take a look at the primary components used.

1. 2" x 3" x 8' Pine Timber

2. 304/316 stainless element housing

3. Heating element

4. Plywood (1/2" thick)

5. Johnson controller (A419)

6. Metal electric housing

7. Variable speed fan controller

8. March 809-PL-HS-C pump

9. 14 gauge electrical wire

10. 14 gauge main power cord

Lets discuss my selection of components. I went with a stainless element housing because I was able to get the parts from a supply house at a reasonable price (and it just looks cooler!). I haven't shown here how to assemble the stainless element housing because there are several ways to do it. I went with a 1 1/2" x 1' nipple as the main housing and connected that to a 1 1/2" tee on one side and a 1 1/2" to 1/2" reducer on the other. The tee contains a reducer bushing from 1 1/2" to 1/2" for the hose nipple as well as a reducer bushing from 1 1/2" to 1", which is the size of the thread that came on the heating element. At the opposite end, there is a 1/2" street elbow, a coupling, and a hose nipple. You could easily go with a 1 1/4" setup as stainless is a bit pricy but I would avoid a 1" setup as the heating element will virtually be touching the walls of the 1' nipple. As stated, I am using a 4500 W heating element but I am wiring it to a 120 V circuit instead of a 240 V. I am no electrician so I am not going to tell you how you should do this but I ran everything by an electrician and all is well in my case. Because I'm running at 120 V, I am only getting 1/4 the power (or 1125 W). A heating element is nothing more than a resistor in a circuit whose resistance is fixed by the material used. So by using some basic equations from elementary physics (e.g., P=IV, V=IR, etc.), you'll see that, in my case, the element is pulling less than 11 amps of current and can be safely wired with 14 gauge wiring (standard for a 15 amp circuit) and plugged into a 15 amp circuit.

I am using a Johnson controller to monitor the temperature of my mash and kick on when it gets below the value I set it for. The metal housing is for an all-purpose electrical outlet (e.g., my aquarium pump to recirculate ice water through my immersion chiller) as well as a switch between the Johnson controller and the heating element. This is important because if the pump is not on and the Johnson controller flips power to a dry element, it will burn up. Thus, I will be sure to set the switch to 'off' any time the pump is not on. The variable speed fan controller is for the March pump. This way I can control the flow of liquid without having to adjust the ball valve on the output. This may be more desirable as it doesn't cavitate the pump or needlessly splash the wort. Be sure to get a fan controller and not a light dimmer (these will NOT work with your pump - I'm told it will burn up your pump!). Both of these electrical components pull ~1 amp of current maximum so as long as my all-purpose outlet doesn't have a large draw (an aquarium pump is less than 1 amp), there should be no problem tripping the breaker even with all components on. By the way (though I shouldn't have to mention this), be sure to plug into a GFCI outlet as you are dealing with electricity and liquids in the same vicinity! That's the idea, lets get to the practical.

In order to flush mount all of the components on the face of the plywood, I had to construct some rough brackets for the metal electrical housing as well as the Johnson controller. I used a 4' strip of aluminum found at big box home improvement stores for the job. Coupled with a few washers in various places, the components ended up fairly flush (though it isn't pretty looking from the back side as is evident in the photo).
After cutting the plywood to the width that I wanted (in this case, 12"), I dry laid all of the components in place to determine the length of the box. I chose to make it as short as possible to allow for greater portability. Be sure to take into account the 2" x 3" that will frame out the face of the plywood and ensure no component mounts will interfere. I quickly realized this after I took the photo (see that the Johnson controller mounts are too close to the edge) and decided to chalk out 1 1/2" lines around the perimeter (the width of a 2" x 3"). You'll want to remember to leave space below both the Johnson controller and the metal housing as the wiring that exits from below has to clear the walls of the enclosure.. Also, I intentionally left all of the hose barbs hanging over the edge of the face (the right side has not yet been cut to length in photo) so that when they drip (as they inevitably will), you won't have a pooling mess on your box. The final length of my enclosure ending up being ~28". I kept the left side clear of any extrusions as I planned to make this the "bottom" when I store it upright (the handle will be on the right side, as we'll see shortly).
With the face cut to length and my 1 1/2" guides marked around the perimeter, I placed my 3 boxes in line with one another from center (see center line drawn across face) and traced out my cut lines. I used a drill to start my cuts at two opposite corners of each square and then cut in each direction along the line with a jigsaw. Since there will be face plates on both the metal box as well as the blue electrical box (to house the variable speed fan controller), I was less concerned with these cuts. For the Johnson controller, I carefully made these cuts and followed up with sandpaper. From here, it's just a matter of framing the face with the 2" x 3" cut to the proper lengths. The back face can be cut but will not yet be installed until all of the electrical wiring is complete.
Even though there are lots of great references online about how to wire a Johnson A419, I thought I would include a picture just to be complete. Again, it is wired for a 120 V circuit and the 'IN' and 'OUT' are labeled on the wires below. The 'IN' corresponds to the prong side of a plug if you were wiring this to be plugged into the wall. The 'OUT' corresponds to a receptacle end of a cord that would be attached to a freezer or refrigerator plug. Notice that both white wires are connected to the second screw on the left. The 'IN' black wire as well as a jumper wire (a short piece of black wire) are connected to the third screw on the left. The jumper wire is also connected to the second screw on the right. The 'OUT' black wire is connected to the third screw on the right. Both ground wires are twisted around each other and will be capped with a wire nut. Other than that, the two small wires for the probe will be screwed into the lower two screws at the upper end of the unit. These wires are ambiguous, it does not matter which goes where between the bottom two screws. You'll need to set the jumper to the right of the probe connections depending on what you want the Johnson controller to do. I'll refer the reader to the A419 user's manual as there are several options.
After a couple coats of exterior paint (just to keep it somewhat water resistant and make it look better), we are ready for wiring. I will omit any detailed discussion of my wiring because, again, I am not an electrician (though I have significant hands-on electrical experience under the watchful eye of a good friend who is a pro and always run any electrical project by him first) and I don't want to be responsible for any mishaps. Instead, I'll post a picture of my near-completed wiring (the hot is not yet connected to the variable speed fan controller) to give an idea.
I used stainless steel lug bolts to fasten both the March pump and the stainless element housing to the face of the box. The housing is attached using 1/2" pipe fasteners and a couple of nylon washers underneath to account for the lift from the tee and the reducer. Be careful not to overtighten (I actually caused a leak on the top sides of the long nipple at the connections - once I loosened them up, all was fine). Also visible here is the main power cord, which I wrapped around two coat hangers mounted in opposite directions. I used a water resistant face plate for the extra outlet and element switch just as a safety precaution. As you can see from this picture, the entire unit fits nicely on two milk crates and is about 4" tall. It's a bit heavy (with all the stainless) but still very portable for those of you who, like me, do not have a dedicated space for a brew sculpture. You may have to modify your mash tun to work with this as it will require something similar to a fly sparge arm to return the wort back to the mash tun after it has run through the heating element. I use my sparge arm for the recirculation but you have to be careful when starting to recirculate. If grain is pulled through the system, it may clog the sparge arm (not fun). Otherwise, it works great and switching between the recirculation and sparging is easy. Cheers!