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Espresso machines with Heat-exchange boilers. They allow for simultaneous espresso extraction and milk frothing making them the gateway into prosumer level equipment for home espresso enthusiasts.
If your not familiar with the boiler types, first a quick review. The three types are in order of ascending cost and capabilities: Single-boiler dual-use, heat exchange, and dual boiler. With single boilers, there’s always some waiting between brewing espresso and steaming milk as the boiler has to be at one temperature for espresso and then heat up to produce steam. With a heat exchange boiler there’s no waiting. Steam is always available and lower temperature water for brewing comes from an isolated section within the boiler. You can see how that works in this cutaway model of a heat exchange boiler. Hot water and steam in the boiler transfer heat to the brew water which flows through that separate section within the boiler. The next step up is a dual boiler which has two independent boilers. One for brewing and another for steam and hot water.
With heat-exchange boilers you get more convenience and consistency. There’s no waiting. With a single boiler machine it can take a minute or more to get up to steaming temperature. And you’ll have better control of brew temps. Single boiler machines can be all over the place with regards to brew temps.
The machines we’ll look at have a wide price and feature range. Some basics they have in common? All have an E61 thermo-siphon brew group. Using thermo-dynamics hot water from the boiler constantly circulates through the group to improve temperature stability. All have dual gauges. one shows boiler pressure and one displays brew pressure. And, All have no burn wands on articulating connections for dispensing water and steaming milk.
So what’s different? We’ll let’s start with the Expobar Office Lever. Again, my pick for best value in a heat exchange machine. Read owner reviews and common comments are things like “best build quality for the price” and “for the money this machine is hard to beat." And it’s true, there are no other HX machines of this quality near this price.
The lever is equipped with a 1.5 liter copper boiler, fed by a 2.75 liter water reservoir. There is a Plus model which connects directly to household plumbing for a never ending water supply so you won’t have to fill a reservoir. A Vibration pump moves water and brew pressure is adjustable via the OPV which is accessible behind the drip tray.
Like all Expobar machines the Office Lever has a custom pre-infusion chamber milled into the E61 group behind the shower screen. As an extraction starts some water drops onto the coffee as the chamber fills and with that extra space pressure builds more slowly than on a standard E61. The pre-wetting and pressure ramp up acts as a type of pre-infusion which may improve extractions and help prevent channeling in the coffee puck yielding more consistent extractions.
In use, I love Expobar’s angled portafilters. I find they are easier to attach. But what I really like is how the angle makes them perfectly horizontal when tamping. Now other companies make angled portafilters but they are almost always a few degrees off horizontal. It’s a little thing, but perfect horizontal orientation helps improves tamping consistency.
The frame and exterior case of the machine are nearly identical to that of Expobar’s dual boiler Brewtus machines. Compared to the Profitec and Rocket we’ll look at it’s not as refined but it’s rock solid with some of the thickest gauge metal you’ll find in a machine case. Steam is delivered through a no burn wand and stock single hole tip. Hot water and steam are knob controlled through standard valves.
Please Note: In 2018 the Pro 500 PID was introduced and features a PID temperature controller for more stable temperature and steam control.
The Profitec Pro 500 steps up the exterior finish quality with more detailed craftsmanship. Metal edges are rolled and on close inspection you notice even the drip tray’s internal seams are finished to a level beyond what you see in most machines. A standout feature of the Profitec are the massive valves. I love the square profile and they’re sprung. Very easy to operate, about a quarter turn from closed to fully open. Being sprung they are low wear. You don’t have to crank these valves down to turn them off.
Inside the Pro 500 a two liter stainless steel boiler is the largest in this group of machines. What I appreciate inside the Profitec is simple and effective engineering with attention to detail. Touches like a braided stainless line running off the vibration pump which helps reduce noise. A commercial grade Sirai pressurestat, copper piping with short runs; under the hood this is a well put together machine with quality components.
Next up the Rocket Espresso Giotto and I’m going to include their Rocket Espresso Mozzafiato machine as well. The only real difference in the two is the exterior case. The Mozzafiato has straight side panels with an integrated cup rail while the Giotto has angular side panels and separate cup rail. Each machine is available in a type V version with a vibration pump or the Evoluzione R version which has a rotary pump and can connect directly to household plumbing for a constant water supply.
These Rocket machines are fairly unique. They’re heat exchange machines with PID temperature control. PID in a heat exchange machine? It’s not very common. Now if you’re not familiar with PID, what it does is allow for very precise temperature control. That works great in dual boilers machines with a dedicated brew boiler. But it’s a little trickier in a heat exchange machine because the main boiler is running significantly hotter than the brew temp. For example to get 200 degree brew water On the Giotto you set the PID to 248 degrees.
In our testing, using a Scace device the Rockets produced consistent brew temps. One thing to note, Rocket takes a different approach with the PID showing the actual temperature in Fahrenheit or Celsius in the brew boiler. Most PID equipped machines show a calculated brew temp using an offset from the in-boiler temperature. So on the rocket, You choose your desired brew temp then reference a chart in the manual to determine the PID setting - which will be much higher - to get that brew temperature at the group head.
With most heat -exchange machines you’d do a cooling flush prior to mounting the portafilter and pulling a shot. That’s not the case with the Giotto and Mozzafiato. In our tests we got the set brew temp without a flush. Depending on how you look at it that’s either a feature or a limitation. A feature in that your getting accurate brew temps a limitation in that you can’t quickly try a higher brew temp by using a shorter flush. For those who’ve worked with other heat-exchange machines you will probably need to adjust your technique a bit for the Rockets.
Rocket machines go heavy on the branding from feet resembling rocket engine nozzles to badging front and back and the iconic R on the steam knob. Standard valves feed no burn steam and hot water wands. All come with a stock two hole steam tip. The PID control and display is hidden behind the drip tray. Casework is refined and is similar to the Profitec in quality. There are some slight differences. On the Rocket the drip tray frame is spot welded to the main chassis. On the Profitec no welds, you'll find it’s a continuous frame front to back. Rocket machines come with useable tamper, and of course it’s etched with their logo. The other machines come with plastic tampers which you’ll want to replace right away.
Inside the Rockets, the copper boiler is 1.8 liters. The internal plumbing is a little more complex with more components and longer runs than you have in the Pro 500. In the long-term I’m a fan of simpler engineering using fewer components. It generally adds up to better reliability.
So, recommendations. If you’re looking for value you really can’t do better than Expobar Office Lever. There’s really nothing comparable on a price performance basis. It’s a solid machine with a long track record. The Profitec Pro 500 offers a more refined finish quality, superior valves and the keep it simple engineering that’s elegant and reliable. The Rocket Giotto and Mozzafiato add some flash with unmistakable branding, unique PID control and plumbable rotary pump driven options. Just be aware those options start getting you into the price range of dual boiler PID machines.
Now If you have more questions on these machines or anything coffee, use those comments and I’ll be sure to get you the answers.