Jacketed Fermenter article for Zymurgy

Here is a nearly completed draft of an article I am writing for Zymurgy. I am hoping to get feed-back to help me finish it up.

“We Seek the Grail...”

My home brewery begs the question as to when enough is enough. Do we really need aeration stones, two-zone plate heat exchangers and steam kettles to turn out a drinkable six-pack of suds? We all know the answer, and yet for most brewers there is an allure in gadgetry. We make the best with the pot in hand while dreaming of the two keggles in the bush. And for some of us the quest for that next great thing is driven by a nearly crusader’s passion.

Much of the quest for gadgets is driven by a desire for control. Timers, thermometers, hydrometers and scales have all become standard gadgets for producing consistent beer. There are, of course, practical limitations and reasonable individuals who will tell you control is an illusion. Yet the Siren’s song of precise control is hard to ignore.

Conical fermenters have become popular in recent years in part because of their beneficial design and the control it provides. A primary benefit is the ease of separating the yeast from the beer. In the case of traditional carboys and buckets you need to transfer your beer into a secondary container, which means cleaning and sanitizing each piece of equipment that comes into contact with the beer. With a conical, you can simply draw off any break, trub or yeast you wish through a dump valve. Likewise, samples for evaluation are easily taken through a racking valve. Further, some conicals are designed to hold pressure, which helps prevent airborne contamination and allows for sanitary transfers using CO2 pressure.

An additional benefit of many conicals is stainless steel construction. Stainless steel resists scratching, and staining. It is inert and so it will not carry flavor into a beer. It is impermeable to light, odor and oxygen and will not break when exposed to heat, cold or an unintended trip to the floor.

Conicals come in a variety of sizes, which allows for single vessel fermentation. This size benefit can also be a disadvantage when it comes to cooling. While smaller vessels fit in refrigerators, larger ones require other solutions. Many strategies, such as the use of cooling coils and cold rooms, are successfully used for chilling conicals. I initially installed internal cooling coils that, while effective in cooling, presented a cleaning nightmare.

Jacketed, conical fermenters, or uni-tanks as they are commonly known, are standard fare in the micro-brewing industry. Their stand alone design allows for individual control and conservation of valuable floor space. The cooling set-ups are generally straight forward and sometimes amazingly simple. Thermo-couplers in each fermenter signal digital temperature controllers to turn circulation pumps on and off to circulate chilled glycol through fermenters’ jackets to control the product’s temperature. The better commercial conicals have zoned jackets, including jacketed cones. Less expensive models may have only a single, small, jacketed area. But in every case the goal is control, simple and effective.

I recognize the idea of a jacketed conical fermenter for home brewing is ridiculously over the top. It is neither necessary nor practical. But honestly, since when has practicality really been part of the equation? “The Practical Brewer” indeed!

The quest for my grail of gadgets began with the winning of an on-line contest. The prize was a gift certificate from Toledo Metal Spinning, the manufactures of the conical hoppers we all crave. My prize was sufficient to purchase two large hoppers. Yet as I explored the choices an idea was born: “What if two could become one to create a single, perfect, jacketed fermenter?” The idea was obviously impractical, but we’ve been through that.

Toledo Metal Spinning manufactures 16 different hoppers, ranging in volume from .1 to 51.1 gallons. PDF files are available for each hopper, providing specific dimensional information. Only a handful of the company’s hoppers are useful as fermenters, but two of their models are perfectly suited for my design. The dimensions of the 21 gallon model, TMS201014, allow it to nest inside the 24.1 gallon model, TMS221014, with less then a ¾” gap between their walls. This gap is perfect for circulating glycol around the fermenter to regulate its temperature. Unfortunately, the standard outer diameters (OD) of the vessels’ upper rims are not compatible for nesting. Fortunately, the company offers a variety of custom modifications. Specifically, they are able to trim the inner hopper (TMS201014) so its rim OD matches that of the outer hopper (TMS221014). Problem solved, obsession begun.

My design is relatively simple. (reference image #1) A ½” stainless coupling is fitted and welded into holes cut in the sidewall near the top and the bottom of the larger hopper. These will serve as the jacket’s inlet and outlet ports through which coolant will be circulated. (reference image #2)

Next, the bottom few inches of the outer hopper is removed to allow the tip of the inner hopper to protrude. This allows for a relatively simple union to be made at the bottom of the jacket. The matched upper rims are then welded together, creating a complete seal around the upper lip. (reference image #3) This weld must be ground smooth to allow a proper seal on the finished fermenter.

Finally, a donut shaped plate, a metal ring of sorts, is cut to fill the space between the bottom of the exterior jacket and the outer wall of the interior jacket where it protrudes. This ring is welded in place, creating a seal at the bottom of the jacket. (reference image #4)

There are numerous designs for legs and stands. My fermenter is supported by three stainless pipe legs which have been welded to the outer wall. Consideration should be given to the height of these legs, as well as their stability. A friend, welder, and fellow homebrewer, Bret Haskins, constructed a bracketing system to mate the round pipes with the cylindrical body of the fermenter, providing exceptional strength and stability for the legs. (reference image #5)

Another major consideration is the lid and seal of the fermenter. This is an area where you ingenuity needs to shine as you determine the system that is best suited to your needs and budget. Toledo Metal Spinning sells both flat and domed covers. Other companies, such as Blichmann Engineering and More Beer, successfully utilize gaskets and clamps on their systems. My fermenter uses a Blichmann gasketed top with a wrap around barrel clamp. (reference image #6) This system is air-tight and very satisfactory.

A drawback of my jacketed design is that it does not allow for the use of the type of separate, rotating, racking arm preferred by many conical owners. To compensate for this, a sanitary T is attached to the bottom of the cone. (reference image #7) A racking tube is inserted through the vertical arm of this T, while the horizontal arm serves as the dump port. The racking tube has a T tip to help prevent clogging during fermentation. Its length is such that it rises a few inches into the cone, allowing the beer to be racked off the settled yeast and trub. Whatever racking system you choose it should be removable for easy and thorough cleaning.

My fermenter is cooled with chilled glycol supplied from a commercial glycol chiller. This chiller was originally used to cool draught beer lines and contains a compressor, heat exchanger, glycol reservoir and digitally controlled pump. This chiller was given to me and while they are available commercially, they may be beyond the budget of even the most gadget obsessed brewer. Other systems can be developed, utilizing freezers, pumps and digital temperature controllers. In my system the glycol chiller pumps glycol into an Igloo cooler that serves as a secondary reservoir. (reference image #8) The chiller recirculates chilled glycol through this secondary reservoir, keeping it at a set temperature as determined by its digital temperature controller. A second pump, controlled by a Ranco Digital Temperature Controller (model ETC-111000-000) with a thermo-coupler in the fermenter (reference image #9), recirculates this glycol through the fermenter’s jacket as needed to maintain the desired fermentation temperature. In cold weather, the glycol chiller can be turned off while an immersion heater is utilized to warm the glycol for recirculation.

By and large my fermenter is complete; although I am sure I will find other ways to tinker with it soon enough. I will probably insulate the exterior and play around with clean in place ideas. But for now I plan to simply enjoy the fruits of my quest and I dream of my next conquest.

So, what does anyone know about digital flow meters anyway?

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