Home-Designed Modular RIMS Setup

I’ve always loved craft beer, but I actually started out my home fermentation hobby by making cider. I began brewing when I realized that I could fill my carboys with wort in between apple harvests and have something to drink when the cider ran out. I borrowed a two-burner camp stove and stock pot from my father-in-law, purchased a couple of extract kits from the local homebrew store, and was off and running. I quickly moved to all-grain brewing, acquired better kettles, and built a mash tun from a 10-gallon (38-L) insulated beverage cooler. I brewed many infusion mash batches and was fairly pleased with the results. One thing that always bothered me about my wort production, though, was the inevitable loss of temperature during the mash. Books by the master brewers said that mash temperature had a huge effect on the body of the finished beer, and I was determined to control that part of my process. So that is where this project all began.

Goals and Limitations

First big question: RIMS or HERMS (recirculating infusion mash system or heat exchange recirculating mash system)? I had a few constraints to work around, which helped me decide. In the area where I brew, I had access to a single 110V, 20A circuit, so without calling in an electrician, I would need to continue heating liquids on propane burners. The camp stove doesn’t have an automated ignition, which meant that I would not be able to use a controller to automatically heat the hot liquor tank in a HERMS system. I was a bit reluctant to punch holes in my new Blichmann kettle, and also felt that a RIMS tube would be easier to take apart for cleaning than a HERMS coil. I did consider the risk of scorching the wort due to contact with the RIMS heating element. Taking everything into account, I decided that RIMS would work better for me.

The next challenge to be faced was storage. I had a vision of mounting the controller, RIMS tube, plate chiller, pumps, and valves on a compact frame that would fit into the approximately 4 ft. x 4 ft.  (1.2 m x 1.2 m) space I had available in my shed and could be easily rolled in and out on brew days. The frame had to hold everything that I need for brewing except for the burners and kettles. I used a program called SketchUp to come up with a design for how all of the brewing components could be mounted. The model helped me figure out the relative positions of all of the equipment and how I wanted to lay out the plugs and door on the controller box.

I had intended to build the frame using strut material or to have it fabricated out of stainless steel stock. I had started pricing out strut material and fittings around the same time that my brewing buddy, Eric, purchased a stainless steel work table for his all-electric build. A light bulb went on over my head: Why build when you can buy? I looked through the tables available from restaurant supply stores and on the web and ended up ordering a 30-in x 24-in. (762-cm x 610-cm), 18-gauge stainless steel work table for a price that was less than what I would have paid for strut or a custom fab. The table has an overhang on the front and sides and a backsplash at the rear, so there was plenty of vertical and horizontal space to mount system components. It also came with locking casters, so I would be able to easily move it from storage to brewhouse.

The top of the table is 34 in. (864 cm) and the top of my cooler mash tun is about 20 in. (510 cm) above that. This setup could be too tall for some brewers. If that is the case, you could purchase a stainless steel equipment table from a restaurant supply store. Equipment tables are shorter than work tables and would work just as well for this build. Personally, I like having the extra tabletop space at a convenient height for writing, but if you don’t care about that, a shorter steel table would do fine.

For my liquid lines, I selected high-temperature 1⁄2-in. silicone tubing as well as Camlock fittings. I found a RIMS tube with pre-welded Camlock fittings and assembled the pumps and valves with Camlocks as well for a unified fitting system.

The Controller

The wiring inside the controller box, which was built using a RIMS component kit that guided me through the steps. 

There are plenty of high-quality, prebuilt controllers available for purchase. I decided to get a kit and assemble my own controller because I wanted to learn how each part of the circuit works so I could fix or extend it in the future. If you are interested in assembling the controller, you must be able to follow an electrical schematic and must be comfortable working with electricity levels that can potentially injure you. Read all of the instructions and cautions that come with the kit, and if you are not completely confident in your ability, spend a little more money and get a prebuilt controller.

I purchased an enclosure that was pre-cut for the PID that was compatible with the controller kit. I used Adobe Illustrator to create a printable template with the layout of the switches, plugs, and indicator lamps on the front and the side of the enclosure box. With the template taped onto the box (as pictured on page 86) and armed with a Greenlee conduit punch and my trusty Dremel tool, I cut holes for each switch, lamp, and plug. Always use eye protection when cutting metal! I did a dry fit of all of the components, removed them, then painted the box with the traditional hammered metal black
spray paint.

For me, the RIMS component kit was like putting together a really cool Lego set. I proceeded slowly, worked in stages, and tested the circuit as I went to make sure my controller was both safe and working correctly. I also consulted with the kit manufacturer when I had questions. I used 12-gauge wire for all of the circuits in the box and put spade clamps on the ends to ensure that each connection was secure. I’ve read that you can use 14- gauge wire for internal connections, and that would be something I would consider if I was to build another controller as the 12-gauge wire can be a bit stiff and hard to route. A larger enclosure box would also have made the wiring easier.

The front of the box has a master key switch, an emergency stop button, the PID, and switches for a mash pump, sparge water pump, and heating element. The plugs on the side of the box are for the temperature probe, heating element, and two pumps. I cut the neutral bus on the 110V receptacle for the pumps and wired each plug separately so I could turn them on and off independently.

I used 3⁄4-in. square aluminum stock to attach the controller box to the backsplash of the table. When drilling holes in the stainless steel table, use eye protection and cutting oil to lubricate your drill bit. The mounted box is very stable and at a convenient height for monitoring the PID display and operating the switches.

My controller box has a master key switch, an emergency stop button, the PID, and switches for a mash pump, sparge water pump, and heating element. The plugs on the side of the box are for the temperature probe, heating element, and two pumps.


I prototyped my liquid flow by mounting the pump and RIMS tube on sawhorses, planks, and some shelving supports. A couple of iterations on the sawhorse setup brought some important lessons. I found that when the RIMS tube is mounted horizontally and wort is pumped from the lower inlet connection, air in the tube is forced out of the outlet instead of being trapped in the tube. I also found that the pumps are easier to prime when they are mounted as low as possible. While brewing batches on the prototype, I learned that switching the output line of the mash pump from the mash tun to the boil kettle is messy and that hot wort poses a burn risk. To minimize the number of hose changes, I bought two three-way valves and fitted them with Camlock connectors. I placed one valve at the outlet of the mash pump. That valve switches between the RIMS tube (recirculation) and the boil kettle (sparge). I put the other valve at the inlet of the RIMS tube and plumbed that to switch between the mash pump (recirculation) and the sparge pump (sparge).

While I was experimenting, I added a bulkhead fitting at the top of my mash tun that leads to a Loc-Line hose inside. The hose lets me control the level of the wort return; I can put it underneath the liquid surface during recirculation and lift it out of the liquid during fly sparging. I mounted a cheap plastic aerator attachment to the end of the Loc-Line to divert the wort stream and minimize channeling in the mash bed.

The RIMS tube kit came with tri-clover (TC) clamps that were welded to M8/1.25 bolts. I drilled two holes in the overhang of the tabletop and attached the clamps to the table. To install the RIMS tube, I open the TC clamps, drop it in, close the clamps, and tighten.

A Loc-Line hose attached to a bulkhead fitting lets me control the level of wort return. I can put it under the liquid surface during recirculation and lift it out during fly sparging.
The RIMS tube’s tri-clover clamps are attached to the overhang of the tabletop. To install the RIMS tube, I open the clamps, drop it in, close the clamps, and tighten.

Pumps and Liquid Lines

I mounted the mash pump on the left side of the bottom shelf of the table and the sparge pump near the front of the bottom shelf. Both pumps have a ball valve mounted at their outlets to control flow rate, and the mash pump has a tee with a garden valve to help with priming. Once the pumps and RIMS tube were in place, I created a set of liquid lines by cutting tubing to fit the distances between the components and installing the Camlock fittings. Having a set of hoses that are all different lengths doesn’t bother me, and cutting everything to fit minimizes the distance that the wort has to travel between vessels.

My plate chiller also came with convenient mounting posts, so I drilled two holes in the left side of the tabletop overhang and mounted it on the left side of the table.

Dialing in the System

The Auber PID model that I used has several parameters that affect the accuracy and stability of the temperature of the wort. The first step towards getting those parameters in the ballpark is running the auto-tune program in the PID. I added a couple of gallons (8 L) of water to the mash tun, started recirculating through the RIMS tube, and ran auto-tune according to the instructions that came with the PID unit. During the auto-tune process, the PID turns the heating element on and off rapidly and measures the resulting changes in temperature, then uses that data to adjust how rapidly it cycles and for how long. After the auto-tuning program was complete, I continued to run the heater and checked the temperature of the water in the mash tun with a Thermapen. The Thermapen and PID didn’t quite agree, so I used the PID’s temperature offset function to set the PID to the Thermapen reading. I used the Thermapen to verify the temperature during my first few brew sessions and found that I still had to make small adjustments to the PID temperature offset each time. I believe the minor inaccuracy in temperature was due to the small mass of water that I used in my initial auto-tune run and subsequent adjustments.

The recipes that I like to brew often contain 20% to 40% wheat. Wheat, oats, and other glutinous grains are notorious for creating sticky, impermeable mash beds in recirculating systems and contribute to “stuck” mashes where the wort stops flowing through the mash bed. Because the RIMS element heats wort directly, a stuck mash can be more than annoying; if wort isn’t flowing over the heating element, it can overheat and get scorched. I now routinely add rice hulls if the grain bill contains any sticky grains.


I’ve brewed more than 25 batches using my RIMS table, several of which have won gold medals at regional competitions and popularity awards at local homebrew festivals. I was even able to load up my system and bring it to a company picnic for a field brewing demonstration! Recirculating the mash results in extremely clear wort in the boil kettle. The system routinely holds mash temperature at plus or minus 0.5 °F (±0.25 °C). I’ve noticed that the temperature appears to be more stable when I’m able to run the recirculation at a higher flow rate. I’ve been eyeing flow meters for the system to see if I can quantify the relationship between flow rate and temperature stability.

Recently, I’ve started doing step mashes, and I’ve found that my RIMS system can raise the temperature of a 5-gallon (19-L) batch by 0.5 °F (0.25 °C) per minute, which is acceptable for protein or ferulic acid rest steps. Most importantly, I have fun on my brew days and enjoy the satisfaction of brewing on a rig that is designed to fit my process.

Issue: November 2018