Gaggia Classic Pro E24 Review

Gaggia’s newest update to their flagship semi-auto has arrived. The Pro E24, as this latest version of the Classic is known, is the same as its predecessor in every way…but with one significant difference: the boiler is made entirely of brass instead of aluminum. 

Theoretically, the switch to brass should mean the Pro E24 has increased capacity, boosted steam power, and improved thermal stability. 

Read on for a full review of the Gaggia Classic Pro E24: I’ll do a direct comparison of boiler specs between the new brass boiler and the old aluminum one, compare the actual performance of the two machines, and finally do an overview of the machine as a whole for anyone who isn’t already familiar with the Classic line. 

Boiler Business

Visually, the difference between the old, aluminum boiler (right) and the new, brass boiler (left) is pretty easy to recognize, even if the aluminum boiler didn’t have some scale caked on—look how much larger the interior of the brass boiler is! Because brass is much more dense than aluminum, Gaggia was able to build a boiler with more room inside without compromising on the boiler’s overall mass (we’ll get back to why that matters in just a minute). The result is a total boiler capacity of 3.68 oz (compared to 2.5 oz on the original). What that should mean is an improved capacity and more steam power, but we’ll touch on that again when we get to testing this thing. 

Another notable distinction in these boilers is their weight. I noted that brass is heavier than aluminum…well, here’s proof. Despite the fact that the new boiler has less physical material to it, it’s more than twice as heavy as the aluminum one (1,349.80 g compared to 506.81 g). 

Because of the huge increase in mass granted by the brass boiler, theory states it should maintain its temperature much more easily and consistently than the aluminum one. For one (and I’m not going to get into the actual thermodynamics of this…at least not in this blog), the heavier something is, the longer it retains heat. So, once your brass boiler is heated enough that it trips the thermostat to stop heating, the rate of heat loss will be slower than with an aluminum boiler, meaning you maintain optimal brewing temperatures longer. 

Beyond that, because of the expanded capacity in the boiler, adding cold water from the reservoir won’t cool the boiler nearly as much. With the old boiler, every ounce of reservoir water accounts for 40% of the total water in the boiler. With the new brass boilers, every ounce of reservoir water added is only 27% of the total volume, so you lose far less heat as the boiler refills itself. 

Test Results

All right, enough theory: what are the actual, real-life advantages of the upgrade to a brass boiler?

First, we tested the heat-up time of the E24 compared to the Evo Pro. As expected, the brass boiler takes a bit longer to reach brew temps compared to the aluminum one: it was 90.5 seconds after flipping the machine on before the brew ready light illuminated, whereas the Evo Pro got there in 71.3 seconds. This difference, however, is largely negligible. For a first heat-up, you should really let the machine warm up closer to 10 minutes to make sure the group head and portafilter are hot. Brewing espresso with an underheated group head and portafilter will shock your brew water and lower the extraction temperature significantly—that means weak, underextracted espresso (yuck). Alas, the group head and portafilter won’t heat up any faster if the boiler gets to temp 20 seconds sooner.

What DOES matter, however, is how well the boiler retains heat. And, like science predicted, the brass boiler outperforms the aluminum one considerably in this respect. We tested this by leaving both machines on over a period of 300 seconds and marking each time the brew ready light went off, indicating the boiler needed to heat the water back up to temp. During this period, the brass boiler switched on only four times, compared to the aluminum boiler’s seven times. 

The practical impact of this stability becomes apparent when you examine the two machines’ brew temperature stability test results. The Evo Pro had a range between 207°F at the start of the extraction and 195°F at the end. Now, in all fairness, we tested the Evo pro a year ago using a Scace device, which can’t approximate the temperature loss that happens when brew water hits a coffee puck, so those early readings that were over 202°F are probably not accurate to what you’d see in an actual extraction. But, it is safe to say that we could expect actual extraction temperatures on the Evo Pro to be between 202°F and 195°F, a range of 7°F. 

By the time we’d tested the Pro E24, however, our very own Marc (you know, from our YouTube channel) had developed a solution to the Scace problem. He devised an original testing device that reads in-puck temperatures during an actual extraction with real coffee. When we used this to test extraction temperatures in the Pro E24, the results were fairly remarkable. The extraction began at 199.6°F before peaking at just over 202°F and then falling to 200°F, a range of only 3°F. 

That’s pretty dang impressive for a single-boiler without a PID, especially when you consider, for example, the Profitec MOVE (a prosumer-grade dual boiler) has an extraction temperature range of 2°F.

When it comes to steam performance, Gaggia claims a 25% improvement on the Pro E24. In our testing, however, both machines heated 5 oz of 42°F milk to 140°F in 24 seconds. Of course, the testing conditions weren’t perfectly equal—when testing the Evo Pro, we began steaming before the steam ready light went on, a known tactic for boosting steam power, since the boiler continues heating while you steam. 

When testing steam performance on the Pro E24, however, we waited until the steam ready light came on (we were also measuring how long that took—60 seconds). This could mean that we didn’t realize the true potential of the brass boiler when it comes to milk frothing. In either case, however, it seems unlikely you’d notice a huge difference in steaming on the Pro E24 compared to the Evo Pro. 

But the improvement to temperature stability is seriously significant. The fact that the Pro E24 competes with the stability performance of much more expensive machines even without a PID is remarkable, and makes it fully capable of brewing truly excellent shots of espresso. 

Using the Classic Pro E24

Brewing espresso on the Classic Pro E24 really couldn’t be easier. You flip a switch to turn it on, prep your puck as you would with any semi-auto, and flip the brew switch to start and stop your extraction. If you want to get into the weeds a bit more, Marc created an easy, repeatable way to get consistent 200°F brew temperatures—you can find his explanation here. 

I used this technique to brew a couple shots for myself and they came out great. I used a bottomless portafilter so we could see the extraction, and yeah: it’s pretty. More importantly, it tastes great. I brewed our house espresso blend, Crema Wave, and you can really see it living up to its name here: lots of crema. Right off the bat I’m getting a thick, honeyed aroma which is really enticing. Sipping on the shot, I’m tasting that honey still, but also getting some nutty, almond notes before it builds to a light chocolatey aftertaste. The espresso has a smooth mouthfeel that’s quite pleasant on the tongue. 

Full disclosure, here: I’m not an espresso drinker. I much prefer a more diluted coffee drink, like an Americano or a latte. So, the fact that I was able to legitimately taste and, more importantly, enjoy the flavors of a shot I brewed on a $500 entry-level espresso machine is kind of astounding. 

But, of course, what I’m really interested in, personally, is a cappuccino. This is a single-boiler, of course, so to make a milk drink I had to wait while the boiler heats to steam temps before I could get frothing—that’s going to take about a minute, but I was able to actually start frothing before the light clicked on, as early as 25 seconds after flipping the switch. From there, I opened up the steam valve to purge the wand and got to business. 

When it comes to actually frothing the milk, I was impressed. I’m an unabashed BZ13 enthusiast and hadn’t used a Classic in recent memory. I was, in all honesty, expecting this smaller, single-boiler to really make my life difficult in terms of getting a good roil and producing microfoam…I was wrong. I was easily able to get enough pillowy foam to make a cappuccino on the E24, and even though I’m no latte artist, achieving that texture is very much on the table as well.

I have to admit, the cappuccino I made on the Classic was every bit as tasty as the ones I make on my BZ13—light and frothy foam with a rich, coffee flavor. I even get the honey and almond notes advertised from the Crema Wave I used.

Final Thoughts

The Gaggia Classic Pro E24 is the same great machine that’s garnered the love and respect of a small army of espresso enthusiasts and tinkerers…just better. A commercial-grade machine with real, metal components and a 58mm group head for around $500 is, as far as I’m concerned, the very definition of value…and the addition of a brass boiler really does make a difference. 

I remain surprised and impressed at the steam performance the E24 delivers. Look, I won’t be trading my BZ13 for one, but if I had to, getting used to the work flow making a milk drink every day on the E24 would be fairly easy, even after being spoiled by a heat-exchanger. 

I’m also a pretty big fan of the look of this machine. At this price point, most of your other options are going to have a lot of plastic on them. The Classic, however, is primarily metal, and it comes in all sorts of fun colors, so getting one that matches the style of your kitchen is pretty easy. You'll also notice the handsome wooden accents in the photos we took for this blog—our friends over at Wiedemann Manufaktur create a wide range of stunning knob and handle sets for the Classic, as well as tampers, WDT tools, and more. 

In all honesty, if you’ve already got yourself a Classic Evo Pro, I don’t think you need to rush out and upgrade to the E24. But, if you’re looking at entry-level espresso machines to kickstart your home barista hobby, the Classic Pro E24 is absolutely the way to go.