I had been using a Rancilio Silvia for years, and had modified my Silvia to have outstanding performance for a single boiler home espresso machine. But I couldn't froth milk while steaming, and steaming milk upset the Silviaís temperature equilibrium, requiring a lengthy period for the Silvia to recover. I knew that the double boiler concept was inherently superior to single boiler or single boiler with heat exchanger machines, but I didn't like various aspects of two small double boiler machines currently on the market and I couldn't afford a LaMarzocco 1 group. So I decided to keep my eyes open for the next best thing - a single boiler heat exchanger machine intended for commercial service. I didn't want to go the Isomac route, or buy any of the other e-61 machines since they all had small boilers and rather anemic heaters by pro machine standards. But I wanted the actively heated group that comes on the Isomacs, ECMs, etc. I also wanted a bog honkin boiler and a big honkin heating element and some damn muscle. So I waited for an Astra Gourmet to come up for auction on ebay.
I eventually won an auction on a Gourmet GS. A synopsis of my ebay buying experience is included in the section on buying experience.
Attributes of the Astra Gourmet series of machines that make them excellent performers are the group type, boiler and heating element size, heat exchanger size, pump type, and choice of hardware. Iíll now address each of these components.
A lot has been written on the CG site, alt.coffee and elsewhere about the virtues of the actively heated e-61 group. The main advantage of the e-61 group is that the group is heated during idle periods by water flowing from the heat exchanger. Hot, less dense water near the top of the heat exchanger flows through a delivery pipe into the top of a reservoir within the group, where it cools. The heavier, cooler water sinks to the bottom of the reservoir and flows through a return line back to the heat exchanger, where it is reheated. The convection loop operates all the time, with no pump or anything. Itís a very clever way of maintaining group temperature. In addition to the thermosyphon loop, the Astra group uses 58mm portafilters. 58mm is very common in pro machines, and it turns out that many manufacturers use similar enough components that one can interchange portafilters and brew baskets. Since I particularly like the LaMarzocco portafilter with Swift / LaMarzocco straight sided basket, the interchangeability is a definite plus.
The Astra boiler and heating element are huge. The nickel plated boiler is big enough to store a lot of heat. This means that the heating and cooling cycle dictated by the commercial grade Sirai pressurestat lopes along at a slow pace, taking almost 2 Ĺ minutes to cool from a boiler pressure of 1.3 bars to 1.1 bars. Heating that mass of water back to 1.3 bars only takes a few seconds, due to the big heating element. At 2kW, the heater is about as big as you can practically stick on a 20 Amp 120V circuit. For you math majors, the current draw is 2000 / 120, or about 16.7 amps. On a 20 amp circuit, that leaves you just over 3 amps to run the pump and the grinder. The heat stored within all of that hot water, and the heating element capacity are really useful when steaming. In order for the hot water to flash into steam, sufficient energy must be added. That energy gets supplied by the superheated water, which drops in temperature as steam is produced. Since the heating element is such a powerhouse, enough heat gets added so that the whole system can keep up under continuous duty conditions. Steaming a latteís worth of milk takes 18 seconds on my machine. So you can reasonably pull a shot and steam a pitcher of milk at the same time. Under conditions of pulling a shot a minute, the machine has enough power to maintain boiler pressure. Cool, huh? Itís kind of like having a 200mph car. You donít need that muscle all the time, but sometimes you wanna have fun, or you need a substitute for reduced male function, or you need to impress someone. Of course if you plan on impressing the cops, I suggest you do it by inviting them over for coffee and producing 5 cappas in 5 minutes, rather than by demonstrating your ability to drive from DC to Orlando in 6 hours.
The heat exchanger is sufficiently large to handle continuous duty conditions. My dimensional measurements peg the heat exchanger volume at about 150 cc, or about 3 double shots worth of volume. My practice is to flush the group for 5 seconds immediately prior to brewing. Measurements of the brew water temperature produced by my machine show that the heat exchanger is large enough to handle the 5 second flush and brew a double shot per minute continuously, unlike HX machines with smaller heat exchangers.
In keeping with the pro character of the Gourmet series, my GS is equipped with a Procon rotary vane pump, driven by an Ulka motor. The pump is internally adjustable for brew pressure, and makes a most satisfying rumble when turned on.
Steam and hot water valves are very smooth in operation. The valves are actuated by turning the knobs, rather than by flipping a lever or switch. I prefer this method since it allows easier control of the steam. The valve stems are closed by spring pressure, which is a very clever feature. This design makes it impossible to overtighten the stems, and allows the stems to change length when they become hot, preventing drips and preventing premature wear of the valve seats and stems.
Hot water is supplied directly from the boiler using boiler pressure as the driving force. Volume flow rate is impressive and the water is HOT! Some folks feel that the practice of using boiler water for the hot water supply results in poor tasting Americanos and other drinks requiring the addition of hot water. I personally like this scheme because it allows one to conveniently flush the boiler, reducing the buildup of scale producing minerals in the boiler water. I regularly flush a liter of water from my boiler into a large measuring cup. I periodically taste the water that comes from both the boiler and the group. Over the 3 month period that Iíve used this machine I have not been able to detect any flavor problems with water from either source.
The Astra Gourmet machines provide lots of steam! The steam wand on my machine was made from nickel-plated copper, with a 6-hole tip on the end. The nickel plating was worn off of the tip and end of the wand, so I bought a new wand from Astra. New wands are now made from stainless steel and feature a 4-hole tip. The tip is fabulous. I find it very easy to produce microfoam and my latte art has improved a lot.
Now, Iíd like to specifically discuss the Gourmet GS. The Astra Gourmet is available in semi-auto and auto versions in both plumbed-in and pourover configurations. Unlike other machines, the pourover versions also use a rotary vane pump. My machine, the Astra Gourmet GS, is the semi-auto plumbed-in version. This configuration is ideal for the gonzo coffeegeek. Since itís designed for connection into a pressurized water supply, one never has to worry about how much water is in the tank, unless the whole water supply goes tits up. I suppose that might happen in some of those states that fight over water rights, but here in mellow Maryland weís gots plunny of water to waller in. The fact that the water supply is pressurized to line water pressure means that there canít be any steam or air pockets within the e-61 thermosyphon loop, heat exchanger, or anywhere inside the guts of the Astra. Such vapor pockets produce brewing inconsistencies in my Rancilio Silvia and I presume that they produce similar inconsistencies in other machines whose internal pressure within the heat exchanger is near atmospheric pressure when the machine is idling. Brewing with the Astra semi-auto, or any semi-auto for that matter, commences at the flip of a switch and stops when you turn the switch off. Thus, you have total control of brew time.
My Astra has been running continuously for 3 months now (Oct 2004), so I can comment intelligently on its performance. The brewing performance of the Astra is every bit as good as I had hoped. The Astra produces unbelievably good espresso with amazing consistency. Temperature stability of the machine is very good for a heat exchanger machine. I made measurements of the brew temperature of my machine in the process of learning to use it and these measurements show that with proper group flushing, the machine is capable of producing the same brew temperature to within 1.5 degrees F, with stability during the brew process of about 0.6 degree F. By comparison, my PID controlled Silvia exhibits shot to shot reproducibility of 3.25 Deg. F, with stability during the brew process of 2.4 degrees. I attribute the improved performance of the Astra to the actively heated group, plus the large boiler and heat exchanger. While numbers may seem abstract when it comes to taste, I can say with certainty that you can taste the improvement. I still own my Silvia, and the Astra edges it out. The Astra really shines when compared to heat exchanger machines without actively heated groups. I recently made temperature measurements of a 3-group machine with non-heated groups, in service at a local coffee shop. The machine was tested under continuous duty conditions of brewing a double shot a minute. Shot to shot reproducibility of this machine was a whopping 11.3 degrees F, with stability during the shot of 1.5 degrees.
Where the Astra really blows away my PID Silvia is in the steaming department. Itís just effortless! Ten ounces of milk in a 20 ounce pitcher froths in 18 seconds to gorgeous microfoam. And I can froth while brewing, which is a total gas. No more waiting for the boiler to hit steam temperature for me!
Youíve probably guessed that I really like the machine, and yeah, youíre pretty damned perceptive. But another really good reason to buy one is the service provided by Astra, and particularly that provided by the engineer / owner, Richard Hourizadeh. As part of my positive ebay buying experience, my machine arrived at my doorstep pretty much destroyed by UPS. Once my clear ownership of the machine was established, I set to work restoring the machine to new condition. Richard was extremely helpful and forthcoming with information. Later, when I became interested in optimizing the thermosyphon loop, Richard once again stepped right up and gave me insight into how the machine worked that I would never have figured out on my own. You should just get one of these things because Astra service rocks.
If you got this far into my review, you also know how the story is gonna end. Yeah, youíre right. Iím gonna say that you should definitely buy an Astra Gourmet if you are looking for a commercial duty, one-group machine. Itís a rock solid performer, and if you get one youíll live happily ever after. If you buy a new machine itís worth dealing with Astra directly at www.astramfr.com. You may save some bucks.