Induction Brewing

Hard though it is to believe, it was more than four years ago that I delivered my presentation about the magic of induction brewing at the National Homebrew Conference in Philadelphia. Shortly after the conference I wrote an article in Brew Your Own on the same topic, giving me an even larger audience to expose to what I considered then (and still consider) the best possible heat source for homebrewing. In the ensuing years, I won over a healthy number of converts to induction, as did many others who discovered and appreciated the same advantages I did, and it’s no longer rare for me to hear that someone is converting to, adding, or beginning with an induction-powered brewery to handle their homebrewing needs. Mission accomplished?

Not quite.

Thanks to the lessons learned, tested, reinforced, and incorporated over the past several years of watching and talking to induction brewers (and continuing to brew 30–40 batches per year on my own system), it is now time to revisit induction brewing. Not everything is new, of course; a lot of what follows is more in the nature of confirmation, meaning that I no longer have to qualify the answer to a good question with, “I’ve never tried it, but based on what I’ve seen and heard, that should be possible . . .” Some genuinely is new, too, especially the methodical and practical improvements I’ve made or been witness to. And, of course, there are still things we don’t know — but not nearly as much, as the blank spots on the induction brewing map have started to fill in.

What is certain, though, is that induction is now a demonstrably, empirically, and practically valuable and viable alternative for brewers, either as a primary (or sole) heating method, or as an adjunct or supplemental option for brewers who still prefer to do some of their brewing on more traditional gas-powered burners. I hope, though, that you will at least consider making the jump to what I’ve often found (and now have a lot more data to support!) to be a faster, easier, simpler, and maybe better brewing system. Before we jump in, this is the part where I put in the necessary caveat that I am not a physicist, metallurgist, electrical engineer, or a profiteer of the construction, sale, or use of induction elements. I’m just a fan.

A Brief introduction to Induction

I promise, this won’t take long, but I’m sure there are some reading who have no idea what induction is. Simply put, induction is a method of converting electrical energy into heat. An induction unit consists of a casing (preferably of metal, though some plastic units are hardy enough to do some small-batch brewing; more on that later), an internal fan and copper coil, a glass cooktop, and . . . that’s pretty much it. No resistant coils, combustion, or any other heat-generating component. So, where’s the heat coming from? That’s the best part: An electric current passes through the copper coil, creating a fluctuating magnetic field, which, when in proximity to ferromagnetic material (including several varieties of stainless steel, as well as cast iron) creates vibration and friction at the molecular level within the ferromagnetic material itself. It’s the pot that heats itself, not the element. One fun trick that housewares and kitchen supply stores do is to take a pan that’s been cut in half, crack an egg or lay a stick of butter across the pan side and over to the non-panned side, and watch folks’ puzzled faces as the egg half-cooks and the stick of butter half-melts on the pan, but sits inert on the element itself. Try that on a gas burner!

So what’s good about this technology? Well, for one, it’s fantastically efficient. When you use a jet burner, most of your heat is blowing right out and around the sides of the pot, so when you fire up that 120,000 BTU burner you’re really only getting a fraction of that energy. Like car enthusiasts say, it isn’t how many horses you have, it’s how many you put on the ground through the tires. My 1800W induction element (which runs on any standard 120V wall outlet) only produces the equivalent of just under 7,000 BTUs, but I get the heat energy out of almost every single one of them. It’s also cheap — assuming you run the element for two to three hours during a typical brewing session (heating mash and sparge water, then boiling) you’ll expend up to $10 worth of propane or $5 worth of natural gas — but only about 25 cents in electricity, at 1800W, or two bits with a larger and more-powerful 3500W unit. They’re also cheap to purchase, easy to clean (no hot spots from flames or coils means no scorching), quiet (just the sound of the fan), provide a gentle boil that minimizes evaporation and makes boil-overs all but impossible under most conditions, and safe (no open flames, so no babysitting the fire while it boils!). As if all of that isn’t good enough, it’s also what allows a lot of brewers to move from garages, sheds, and driveways to a cozy spot inside.

So, what’s the catch? To be honest, there aren’t many. In fact, there are a great many fewer than I once believed there were. Homebrewers are a creative and industrious bunch, and over the years I’ve learned that many of the caveats I would have to add to my pitch can be safely tossed, with some light engineering or smart design. First is the question of volume: There aren’t many limits on what you can get to a boil with fire, but electrical circuits and wiring can only accommodate so much electricity, so the energy might limit your batch size (more on that in a moment). Time is also sometimes noted as a limitation, as the lower energy output means a lower rate of temperature increase. You’re also limited in terms of the kettles you can use, but thankfully that’s less of a concern these days, with more and more equipment on the market! Aside from that, though? There’s not much holding you back, and as I noted, these are more questions of design and engineering than actual limitations.

More details can be found in my original feature on this topic (in the March-April 2014 issue of BYO) so feel free to take a trip back in time and review that, but for now let’s jump into the lessons learned and new developments in induction brewing.

Size Matters

Once upon a time, I was convinced that batch size was induction’s greatest limitation. Now, I’m not so sure — even at the relatively modest power output of an 1800W induction unit! And I don’t mean in the sense that “well, you can boil anything if you wait long enough and leave the lid partially on,” but in the sense of, “wow, I didn’t realize insulation and pot geometry could have that big of an impact!” Discussions with induction brewers and my own experience have convinced me that size is rarely a serious concern for induction brewing, given the proper approach.

Let’s start with the obvious: Almost any induction element can get at least 2–3 gallons (8–11.5 L) up to a boil, even the small 1300W units. Certainly, it’s no issue for the 1800W units, either. If you’re using this as a backup or pilot system, only looking for a couple of gallons (8 L) or less of finished wort, then you’re home free. Almost any unit using almost any kettle, insulated or not, will work.

Moving up in scale, though, takes some minor adjustments. When last we met, I noted that I brew 4.25-gallon (16-L) (finished) batches, and that my 1800W element and Reflectix-insulated kettle brings just under 5 gallons (19 L) of wort to a gentle boil, but that I hadn’t had direct experience of larger batches at 1800W. That’s no longer the case. I’ve since seen boils of up to 7.5 gallons (28 L) with an 1800W unit, and they didn’t take much longer to get there than my 4.9-gallon (19-L) boil. How? Still the same answer: Pot geometry and a little insulation.

You’ll want a unit with the widest possible coil to really spread the heating evenly and broadly, but you can help out by using a pot with a diameter of 13 inches (33 cm) or less. This puts a lot of good kettles on the table — perhaps most perfectly the Tall Boy 8-gallon (30-L) kettle, which is induction-capable and sports a diameter of only 12.5 inches (32 cm). When paired with two wraps of Reflectix (essentially just an inexpensive metallic bubble wrap), boiling is easy. I spoke to one brewer who started with four courses of Reflectix, but backed it off to two because the boil was more intense than he wanted! And this is all off of a standard wall outlet. Admittedly, you won’t be able to run much else on that circuit while your unit is running, but that’s a pretty small price to pay (and you can usually run 1800W plus some lights or electronics without a trip). Full-sized 5-gallon (19-L) finished batches are definitely on the table with an 1800W induction unit.

If you should find yourself in need of even larger batches, you can upgrade to a 3500W unit if you have access to a 220V line, like the kind that run your electric dryer or oven. Those units not only create absurdly fast heating for smaller batches, but also increase your potential output to nearly 15 gallons (57 L). I’ve also heard of folks taking advantage of their home’s natural infrastructure rather than running a new line: Some simply unplug their electric dryer or oven and use that outlet for their brewing, then re-attach the supply to the appropriate appliance when they’re done (which is also convenient because both are also likely to be near water supplies and sinks!). Another brewer I spoke with simply replaced his dual-fuel range with an all-gas, and dedicated the electric outlet to his induction unit (which he also cooks on). I love homebrewers.

Long story short: Size matters, and induction can give you any size batch you need.

Practical Use Updates

Brewers are also finding and sharing more practical applications and adaptations to make induction brewing easier.

Induction means you can heat as you lauter and sparge, provided you’re using high-temperature tubing: From the second you start running off into the kettle, you’re double-dipping on your brew time, sharing the run-off time with the heat-to-boil time without running the risk of melting your tubing. Even to the extent that induction often takes longer to bring to a boil, it won’t extend your brew day. Sure, you could always sparge faster, but with heat-as-you-go there’s no need. A slower run-off rate will also mean higher efficiency.

Induction also means much more consistent heat than flames, which means you can more-easily calculate how long it will take to heat your water additions. Rather than thermometer-watching, you can set a timer and occupy yourself with something more worthwhile.

I’ve also found that operating a single induction unit (rather than two) is also capable of simplifying and speeding up your brew day. One option is to go no-sparge, mashing in with the usual water-to-grist ratio and then adding a jumbo-sized mash out addition with the remaining water before draining off (just once, instead of a separate lauter/sparge) into the now-empty kettle. Induction is also very conducive to brew-in-a-bag (BIAB) applications. Not only can the kettle be insulated to hold the temperature relatively steady at the desired mash temperature, even with the heat turned off, you can run the unit at a lower wattage to slowly “ramp” temperatures without fear of burning the malt. With a little trial and error, you can create the kinds of sophisticated stepped/ramped mashes that commercial breweries often use, then pull the bag and bring it straight to a boil. This “no hot spot” advantage is present throughout the process, which not only means more evenly distributed heat, but an easier-to-clean system.

Four years ago, there were some lingering questions about the weight of the kettle and the wort, and whether that weight would exceed the weight limit of the unit, causing cracked glass or (some noted) a “squealing” sound from the unit itself. I’ve never had an issue, nor have any induction brewers I’ve discussed this phenomenon, with either of these — so long as you’re using a metal-cased induction unit. The less-expensive plastic-bodied units may run into this issue, but I haven’t yet seen it there, either (though credible stories can be found in forums). This is not a fatal concern, though. In most cases, to even be facing this problem you’d need a very large kettle, which likely overhangs the edges of the unit itself. Brewers can simply construct a support/stand that is slightly taller than the induction unit, to bear the weight: One major advantage of induction is that the kettle doesn’t need to be in direct contact with the unit to create heat! Much like in horseshoes and hand grenades, “close” counts in induction.

When it comes to insulation, I haven’t yet found a better option than Reflectix. It’s inexpensive, and the data I’ve seen (of varying quality, but still worth considering) seems to support the idea that it works better than other (neoprene, carbon fiber blankets) options. One brewer was very pleased with his fiberglass insulation wrap, but I personally find it far more difficult to work with than the Reflectix, and I can’t envision that it is sufficiently better-performing to make it worth the hassle. Measure, cut with normal household scissors, wrap, tape. Done and done. It can even be removed to clean up the residue of any spills or boil-overs (which remain exceptionally rare with my 1800W unit!) by simply flipping the kettle over and sliding off the insulation, which can then be cleaned and slid back on.

There are three negative lessons-learned that I’d like to pass on. One relates to “induction interface discs” a ferromagnetic disc used as a heat-producer that is sandwiched between the unit and a non-induction-capable kettle. Simply put, these have a very spotty record of success. They seem more than up to the task for ordinary culinary applications like frying an egg, but to maintain a boil of a large amount of liquid, not so much — the modest loss of efficiency seems to be enough to create issues that lengthen the time-to-boil or prevent it entirely.

      My second point relates to safety — specifically burn risk, thanks to the glass surface of the induction unit. Where I’ve heard of injuries from induction, it’s here: Although the unit itself produces no heat, the glass surface absorbs a lot of heat back from the boiling kettle. Though rare, a brewer could catch a burn from the unit during cleanup if they aren’t careful.

      Finally, I would also caution brewers against insulating their induction units for sound. For one thing, it seems gratuitous: Induction units are already pretty quiet! I did, though, hear from two brewers who attempted to wrap the unit to make it even quieter, and in both cases the unit overheated due to a lack of access to the room-temperature air that the integral fan uses to cool the unit.

Still Worth It

Several years in, and with the added input of a few dozen induction brewers, I still advocate for its adoption by brewers. It’s ideal for condo or apartment brewers, with its small footprint and BIAB-compatibility. It’s ideal for those who live in cold climates and don’t relish the idea of standing in the garage or the open air in the dead of winter. It’s ideal for those who brew at larger scale but want a smaller system as an in-house pilot brewery. It’s ideal for those who want the flexibility of brewing larger batches, too, and can put a 3500W unit to work. Heck, it’s even portable: I bring my system everywhere, from beer festivals to brewing demonstrations. Where gas brewers need to move a heavy burner and a propane tank, I can move mine with one hand; all I need is an outlet.

I would also point out that induction brewing itself (and the transition to/addition of it) is still cheap. You can get a 1800W unit for under $100 and I’ve seen sales on 3500W units for under $150. Units of 1200W or 1300W (more than up to the occasional 1- to 2-gallon/4- to 8-L test or experimental batch) can sometimes be found for $20. That’s a remarkably affordable piece of equipment, at all power levels, especially for all that it adds. Brewing on it is cheaper, too. The prices of propane and liquid natural gas are both higher today than they were when I made the switch, but electricity is, on average, about 30% lower per kilowatt hour than it was then.

Finally, induction brewing is still effective. The brewers I know who use it are producing outstanding beer, and for all the concerns I’ve heard voiced about time, boil intensity, hop utilization rates, and more, there seems to be no noticeable effect on quality. The concerns are overstated, or flat-out wrong. This is a fantastic method, and in four years I hope to be revisiting this topic yet again, with more brewers in the induction corner than ever before!

Join us, won’t you?