Flow Heaters

BH Unlimited Update, Nov 22th 2021.

You know we’ve been writing and researching about espresso machines — their history, form, and function — for several months. And we’re publishing the last lessons this week. Of course the final lessons are all about tech and thinking out of the box,  whereas the early lessons were all about steam. It seems like the public got hooked on steam in the early days — Moka pot lovers (with the notable exception of this remarkable achievement ) are still hooked on it.

According to the great Aussie coffee machine collector, Ian Bersten ,

‘There was an idea that the last drop had not been extracted from the coffee until the steam had been applied and that the steam was necessary to make a really good cup of coffee.’

What you notice when you look at most top flight machines on the market is that it’s no longer steam that can’t be relinquished, but boilers themselves. As we watch car manufacturers phasing out combustion engines from new car designs, it seems like the success of companies like Tesla or Waymo (Google’s driverless taxi service) has established a new idea that the heart of the car is not the combustion engine, but just motion, and travel itself. If you apply that logic to espresso machines, you could say the boiler(s) is our combustion engine. It has proven performance but it’s not the heart of the machine.

So this week, to help us wrap up The Espresso Machine online course and certification, we took this question along to Dr Markus Weimer, who is the fabrications expert at the heart of Tone . They make a boilerless coffee brewer — which won the SCA’s best new product this year. Instead of a boiler, this machine has a flow heater (aka flow through heater) which looks like a little maze of water channels embedded inside a plate about the size and width of a beer coaster. We learn about how flow heaters work and about their potential to reduce the carbon footprint of a cup of coffee dramatically.

It makes this interview all the more pertinent for us, knowing that the historical obsession with steam is still in question when it comes to flow heaters. The thing is, if you want to use this for espresso applications, you can actually make steam with a flow heater, as well as hot water. But it takes two or three seconds for it to get going. That’s absolutely fine for home, but marginal for cafe purposes. So are we willing to wait? Or can they speed it up? BH Unlimited subscribers can head in and find out here .

Of course, if all the world’s energy was produced through carbon neutral sources like solar and wind power, we’d be free to crank up the boilers and make the steam punk machines of our dreams. That day may come, but kudos to the folks at Tone — they’re not waiting around for governments to do the right thing by the planet; they’re pushing out … to the boundaries of coffee already.


Tools are in stock for the holiday season

After some classic 2021 delays, our Global (Hong Kong) and North America warehouses are stocked up with cupping bowls, tampers, and pitchers. https://baristahustletools.com


The Coffee Buyer's Guide to Brazil

The mechanical coffee harvester was invented in 1979 by a Japanese mechanic named Shunji Nishimura. Nishimura, like many young Japanese, emigrated to Brazil in the '30s in search of better opportunities, and had quite the varied career, including stints as a coffee picker and a butler before setting up his own repair workshop. Remembering the back-breaking work of coffee-picking, he turned his engineering skills towards creating the mechanical harvester, an invention that has transformed the Brazilian coffee industry.

This week in our Coffee Buyer’s Guide we learn about the harvesting methods employed in Brazil today, and look at how the Brazilian coffee industry has adapted its processing methods to non-selective picking. Brazilian producers have become experts at sorting coffee after harvesting, and raisins, ripe, and unripe fruit are separated at the wet mill to be processed in separate streams.


On the Origin of Arabica

Where does coffee come from? The available evidence suggests that the entire arabica species descended from one single tree, sometime between 10,000 and 1 million years ago. For many years, the general consensus has been that this mother plant most likely grew in Ethiopia, where most wild coffee is found today. Coffee also grows wild in neighbouring countries such as South Sudan and Kenya, but the possibility remained that the seeds had originally been brought there by human activity.

Now new research confirms that the wild coffee growing in South Sudan is genetically distinct from Ethiopian populations, and from nearly all other coffee grown worldwide. This confirms that South Sudan is also an origin for wild arabica coffee, and therefore may have been home to the mother tree that gave rise to the arabica species.

The researchers also found that, of the three commercially grown strains supposedly from Sudan, including one strain of the well-known variety Rume Sudan, two didn’t share any of the unique genetic markers of Sudanese wild coffee. These varieties may have been ‘diluted’ by cross-breeding — or may not have come from Sudan at all. Sudanese wild coffee thus represents an almost entirely untapped — and rapidly disappearing — source of new varieties.


Quick links

Correction: There was a misprint in our last newsletter where we discussed an interview with the new WBrC Champ Matt Winton . In fact, Matt’s currently working with Root and Friends and Collective Bakery in Zurich. Also since last week, we’ve discovered he’s quite a badass skater too.

We mentioned Waymo before. Very fun Revisionist History podcast about that here .

Check out this film about the history of coffee and it’s arrival in Brazil in the Coffee Buyer's Guide.


Our Editorial Policy

At BH we never do ads for products on our website. There’s no product placement in any of our courses, newsletters or blog posts. Our only income comes from what you pay for your subscriptions. When you see machinery or coffee gear mentioned in any of our educational material, or featured in our course videos, we have chosen to use that equipment because we like using it or because it shows you something you need to see. It’s as simple as that.


The Espresso Machine

History, Form, and Function
EM 4.10 • Flow Heaters
EM 4.11 • Boilerless Technology — An Interview with Dr Markus Widmer


The Coffee Buyer’s Guide to Brazil

Growing, Harvesting, and Processing
CBGB 5.03 • Harvesting
CBGB 5.04 • Traditional Processing


As always, we're just an email away if you have any queries! Have great weeks and we look forward to seeing you next time.



To the Boundaries of Coffee,
Team BH

You have Successfully Subscribed!