concept overview

Effective Heat Exchanger

Typical 2-circuit espresso machines have the small disadvantage that the heat exchanger is in constant contact with the boiler water (as it is always filled). The most popular machines have heat exchangers with a volume of up to 400 ml. This means that initial shots are pulled with water that is too hot — even water that may have been sitting in the machine since its last use. Therefore, it is often recommended to do a cooling flush to remove as much of this overheated, stagnant water as possible.

A further disadvantage is that the high temperature causes a significant amount of calcium to be released from the standing water (in regions with hard water). And bit-by-bit, this builds up inside of the heat exchanger.

This problem is avoidable with a change to the design. Instead of placing the outgoing 3-way valve downstream of the heat exchanger on the way to the brew group, it is installed under the boiler. This way the heat exchanger can be led through the boiler from top to bottom as a thin pipe.

After a shot has been pulled, the 3-way valve opens letting all of the water in the brew group and the heat exchanger to leave the machine.

Advantages:

  • There is no water in the heat exchanger that is overheating. When a pull begins, only the approx. 20ºC (68ºF) warm water in the tank is pumped through the heat exchanger and into the brew group, all the while being evenly heated.
  • No calcium deposits from standing water build up in the heat exchanger.
  • The heat exchanger can be very thin, allowing for all the water flowing through it to be consistently heated.
  • Only fresh water is used for brewing (and not water from yesterday as with a few 100ml large conventional heat exchangers).
  • The repositioned 3-way valve greatly shorten the distance from the heat exchanger to the brew group giving water no time to cool off. Additionally, this frees up space to the right of the boiler for a potential 2nd brew group.

Customisable and modular

When one decides to invest in an espresso bar (both an espresso machine and grinder), there are usually considerations regarding the layout and design. Using this website’s Build Your Own Machine feature, you can customize a variety of features to meet your needs and wishes. It starts with the dials on the pressure gauge and the colours of the indicator lamps, on to the external colour and finish, and ends with the electronics. This means development and production are tailored to your machine’s individuality, and so we only build to order.

 

In the course of time, more options will be added and can be applied to machines already built and delivered.

 

When buying such expensive machines, there is always the question of how much money you really need to invest. Of course, you do not want to spend too much. On the other hand, you do not want to invest so little that you would have to buy another machine after a short time.

 

The answer to this question was at the core of Xenia’s development. You can get the machine in a solid basic version to first look, if the possibilities of the machine are not already more than enough. This will be the case for most people.

 

For those who desire to have more, the machine can be sent back and re-equipped for only the difference in price — as if the machine was built that way from the start.

build your machine

 

thermal stability

The heat bridge is an integral part of Xenia’s overall concept. It is made of copper (Cu-DHP) and connects and holds the brew group and boiler.

 

The brew group is thermally synchronized with the boiler and profits from the very even heat generation of the boiler. The copper heat bridge is an important reason for the stable temperature.

Red line = Temperature of the brew group directly where the water flows down into the shower screen.
Blue line = Brewing temperature measured with a Scace device.

convenient and useful features

For a modern household espresso machine, it is more than just preparing a good espresso or cappuccino. It has to prove itself as the ideal choice in several ways.

Footprint

With a width of 27 cm (10.6 in) and a height of just under 40 cm (15.75 in) (with rail), the machine occupies comparatively little space in a kitchen. You still have to take into account space for the grinder (18 cm [7 in] wide x 40 cm [15.75 in] high). Therefore, both would require a working area of about 50 cm x 60 cm (19.7 in x 23.6 in), for example on IKEA’s little BEKVÄM serving trolley.

The machine’s unobtrusive size and few protrusions compliment the simple, elegant form and subtle colors choices.

Drawer Tank for Kitchens with Wall Cupboards

In many cases an espresso machine is placed in the kitchen beneath wall cupboards and then, due to the lack of free space, it is no longer possible to fill the tank from above. Pulling out and pushing back a 25 kg (55 lb.) machine would not be a very practical solution. Therefore, the Xenia can be ordered with a drawer tank that can be pulled out from the right or the left side of the machine.

Cleaning-Friendly Surfaces

The majority of espresso machines are constructed with reflective surfaces. The Xenia also comes standard with a mirror-finished stainless steel exterior (so-called IIID). However, one has the possibility to order the machine with different colored coatings, which have a slightly rough and matte surface, on which virtually no fingerprints or smudges can be seen. These versions are available on the Build Your Own Machine form under the term “eloxal”. The surfaces look similar to anodized aluminum, but are 100% stainless steel.

Water Line Connection

The machine can be easily and affordably connected to your water line. Nevertheless, it is possible to switch to tank operation via a valve without rebuilding the machine. A special feature is that Xenia does not require an expensive rotary pump, but also works with low-noise vibration pumps.

Convenient Operation

The layout of the espresso machine is clearly arranged, the operation itself fairly straightforward. When the grinder is set to the correct coarseness, the grounds tamped with a moderate amount of pressure, the portafilter clamped into the brew head, all that remains is to activate the machine. The brew group is designed so that these simple steps remain easy to take. The portafilter can be firmly attached with very little force —the machine will not move or twist. If desired, the pull automatically finishes after 30 seconds so that the results can be consistently reproduced.

Care, Hygiene and Maintenance

Since most of the action is essentially at and not in the machine, maintenance is quite simple. The mirror-finish panels can be cleaned with water and a cloth.
From time to time, the machine has to be backflushed with coffee oil cleaner. The steaming wand should be wiped off after each use.If water has slight lime content or if you use decalcifiers (as from Britta), then the machine will serve you maintenance-free for many years.
The seal in the group head needs to be changed every 1 to 2 years. Being an E61 machine, this seal is widely available for purchase.

Quick Start-up Time

There are a number of good brew groups and concepts for espresso machines. Most popular is the E61 brew group. However, since the E61 is not as controllable as we wish, we have favoured a slightly different concept.

We have held onto the idea of the E61 to use the heat of the boiler. However, rather than use water we have opted for 6 mm of thick copper. The advantage of this, depending on your region, is that the brew group cannot calcify. A further advantage is that the weight of the machine is reduced, contributing to its light and slim feel.

In addition to the copper bridge, which above all ensures high thermal stability, the brew group can also be heated by means of 2 heating cartridges. Heating cartridges are able to rapidly bring the body of the brew group to the desired temperature. After a while, the copper bridge will be able to maintain the temperature and the heating cartridges will only be activated when necessary.

With two 100-watt cartridges, the brew group reaches the desired temperature after roughly 12 minutes. The heating cartridges are also available in 150 watts.

They are designed in such a way that they extend (parallel to the thermal bridge) over the entire length (70 mm), thus ensuring uniform heating. They are optionally controlled via a screw-in thermostat or a high-quality PID controller, which is common with many machines.

Further details of the brew group are explained here: the thermal concept

 

Made in Germany

The Xenia is engineered and built in Germany. We do not outsource production to low-wage countries because we want to have complete control of our product. This is also due to the high configurability of the machine, which is not compatible with a mass production environment. Some of Xenia’s parts, such as the water tank and indicator lamps, are made by companies here in Germany.

However, our suppliers are not only located in Germany. Many of our partners are based in Northern Italy — especially those who manufacture metal parts according to our specifications.

Some partners come from Switzerland, supplying us hydraulics and electronic parts. Just outside of Europe is a company in Armenia specializing in high-quality thermostats. And further aboard we found a good partner in China who manufactures electronics.

We have a good mix of reliable partners. Our choices were guided, not by nationality and price, but an interest in qualifications and a willingness to cooperate.

Durability

From its conception, the machine brings a very solid and heavy quality. At the core is a 2 mm stainless steel reinforced chassis that is torsion-free in every direction. The panels are made of high-quality stainless steel sheets. The boiler is made of stainless steel, the brew group is made of chrome-plated brass, and the heat bridge is made of a massive piece of copper. In principle, the entire machine is made of materials that effectively do not wear out.

The electrical and electronic components are very robust. However, additional measures have been taken to shield them from the heat, further increasing their longevity.

Thanks to readily available standard parts, the machine can serve you for decades to come.

Should a part become defective after several years, you can rest assured that a replacement part can be found at a reasonable price. For many parts (like the Solenoid Valve) you can choose from a selection of manufacturers. And the machine is constructed in a way that no special tools or instructions are needed to exchange parts.

This machine will easily retain its value for many years. Should you decide to sell it one day, you will have no problem finding a buyer at a good price.

List of Details

  • 2-circuit machine (basic version)
  • upgrade to dual-boiler (in discussion)
  • upgrade to dual PID version (in development)
  • Arduino-based control unit with 32-bit processor
  • uses standard parts (mostly from Italy)
  • precision-manufactured metal parts
  • designed and assembled in Germany
  • heat exchanger without standing (overheated) water
  • actively heated brew group by means of heating cartridges for quick readiness
  • passively heated brew group by means of a copper heat bridge
  • variety of colour symbols and logo text to choose from
  • variety of materials for portafilter handles (plastic, olive wood, metal/soft touch)
  • solid stainless steel boiler
  • optional boiler insulation with stainless steel jacketing
  • non-contact water level measurement via a capacitive sensor
  • water tank made out of Makrolon featuring glass-like transparency and food-safe usage
  • stable and virtually torsion-free base frame made of 2 mm stainless steel plates, supported by rear extending angle braces
  • selection of stainless steel cover panels (for example: mirror, black anodized, red anodized, etc.)
  • tank removal from top or (optionally) side
  • optional rotary valves for water and steam, or rocker valves (extra charge)
  • high-quality rocker switches and indicator lights
  • relatively small dimensions with a small footprint
  • optional water line connection