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Introduction |
Generally Home-Barista.com's reviews do not list suggested improvement. However, given my deep involvement with the Expobar Brewtus User Group, I feel compelled to pass along our collective thoughts on how an already great machine could be made even better:
For those among us who cannot survive more than a page without empirical data, below are some metrics about Brewtus brew temperature performance, plus a few other topics of interest to new Brewtus owners.
Accuracy in reaching dialed in brew temperature. With proper flushing it is accurate within ±0.5°C from the tenth second on.
Temperature variation within a shot. From the tenth second on, it is ~1°C for a two ounce double and 0.5°C for a 1.5 ounce double ristretto. Shot time of 25 seconds
Temperature profile within a shot. It is a typical slant-L temperature curve, with a slight and very shallow gradual rise in temperature from the tenth second on. As mentioned, the rise will reach 1°C for a two ounce double and 0.5°C for a 1.5 ounce double ristretto in 25 seconds. This temperature curve is very different from the typical HX temperature curve in which there will be a gradual decline in temperature from the tenth second on. The HX temperature profile can be further manipulated to create a "hump" at the beginning of the shot. It is practically impossible to create a spiked temperature profile with the Expobar Brewtus.
Back-to-back shots. When doing back-to-back shots, with only ten seconds between them, Brewtus will start showing a rising temperature above predicted temperature from the third shot on. It will reach 2°C overshoot after ten shots. This effect occurs only when pulling two ounce doubles in 25 seconds. Double ristrettos behave differently and will generally not cause a sharp rise in brew temperature for rapid back-to-back shots.
The Brewtus brew boiler has a temperature swing of ~5-8°F off the set temperature, which reaches its peak ~10 seconds after the heat element is shut off. How should this affect your daily use of the machine? There is really nothing you can do about it, and moreover, you are blind to it. The Brewtus does not show you the temperature in its boiler. The interesting thing is that despite the overshoot, brew temperature on average, is still within 0.5°C of displayed temperature assuming you flush the group properly.
In the graph below, you will see that the brew boiler temp oscillates 5-8 degrees Fahrenheit around the set point of the stock controller and the steam pressure oscillates between 1.1 and 1.25 bar. The variation in the steam pressure is due to pressurestat inconsistencies (sticky diaphragm); one of the problems observed in the system was the tendency for the brew temperatures to oscillate with off-idle performance due to the temperature swings of the boiler. These temperature oscillations were not larger than 1°F in usage but were enough to be noticeable.
Both the steam pressure and brew temperatures varied in response based on where in the feedback cycle the brew command came. Notice the frequency of heat cycles along the bottom of the graph. At this time the steam boiler has priority over the brew boiler for heat cycles (via pressurestat).
Note: The Expobar Brewtus uses a non-PID AKO temperature controller. Several Brewtus owners including myself have modified the stock configuration to add a PID temperature controller. While this does allow more refined temperature control to 0.1 degree Fahrenheit, we found no in-cup difference at the same temperatures as the stock controller.
Source: The Brewtus Compendium, by Sean Lennon
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Below is a typical shot profile.
Personally, I prefer to dose and tamp directly into the basket while the portafiler stays locked into the grouphead. I do it for the following reasons:
Regardless of my personal preference, this is not an attempt to lay down the law regarding proper barista technique for a home user or for this particular machine. The range of methods and opinions is wide; I suggest keeping your mind open to all changes in your technique that may improve your espresso experience. Tamping directly to the portafilter has its roots in a commercial environment where speed is paramount. At home, you are not serving a line of 50 people, and you should not bound yourself by that restriction. But again, a skilled barista will produce excellent shots on the Brewtus using the standard tamping technique.
Little things can make a difference. These two improvements make a big difference in usability and electrical power consumption.
The five minutes upgrade - cup warmer tray handles. Add a little grace and style to the Expobar Brewtus and resolve an annoying problem at the same time. Specifically, the cup tray on the Expobar Brewtus covers the water tank refill access. So, to refill the tank you must first remove all the cups before you can remove the tray. This will not affect your coffee quality, but it is a daily annoyance. The solution: The cup tray has four holes 2 on each side which were designed to accommodate tray handles. Alas none come with the Brewtus. However, Lowes happens to have very nice handles that fit just perfectly for $6.98 each. . They are Lowes part number 133819; model number BP9362-G10; Amerock 128mm centers Essential Z Satin Chrome Subtle Arch Pull. You can order them online (link) or buy at your local outlet. The stock screws that come with it are a little too long; you need 1/2" screws. Stop by the nuts and bolts department and pick up stainless steel screws (short) and finishing washers to hold them on.
The 30 minute upgrade - insulate the boilers. The Brewtus two boilers can be insulated with a sheet of flexible fiberglass wrapped around each of them. Insulating the boilers has two main benefits:
The insulation layer is applied by wrapping both boilers together, no adhesive required. You must cut two holes on the top of the boilers to expose the steam pressure release valve on each boiler. Also, wrap the incoming pipe to the E61 grouphead to increase thermosyphon efficiency. Make sure you do not wrap the exit pipe from the grouphead back to the boiler. The insulation layer can be 1/8" or even as thick as 1/2". If it is the former, wrap it around the boiler a few times. You can get the insulation layer at your local Lowe's, Home Depot or hardware store, or get it online (link).
The Brewtus has resulted in something unique in the consumer espresso machine landscape—a user group forum and a file repository website. The website and forum are open to the public at www.brewtusgroup.com and groups.google.com/group/brewtus. Both are great resources and full of excellent advice for the novice and the experience user.
The Brewtus User Group has compiled an impressive Expobar Brewtus User Manual, whose completeness and technical detail far surpasses any manual available for any machine on the market today.
If you are wondering what's involved in PIDing the Expobar Brewtus, check out Sean Lennon's masterpiece, The Brewtus Compendium, in which he documented his double boiler PID project of the Expobar Brewtus. It is the most impressive and detailed documentation of a PID project I've seen to date.
This review would not be what it is without the helpful and brutal comments from Chris Tacy, Steve Robinson and Dan Kehn who went over its first draft. Though I often accused Dan of sucking the life out of my masterpiece using his sharp editing razor, he has been an invaluable asset in bringing this article to its final form.
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