This is what happens when I spend too much time on ebay looking for shoes. I end up with a new project, two espresso machines, and of course knowing more about espresso machines.

I was intrigued by a broken machine that was missing the heater but otherwise, claimed the owner, was perfectly working... what breaks such a simple system?

Step 1: Take It Apart. I Mean, Completely

This is not really needed. Over the years I learned it is my own compulsion for cleaning objects and my curiosity for how the original designer thinks :)

The machine is made of a simple frame, sturdy enough to hold the basically standard E61 brew group in front (it weights about 10kg), the 2L tank in the back, the piping connecting to the pump and to the different elements in front, the water reservoir and the minimal electronics.

The damage to the machine was quite clear: the tank has a visible leak that could come from the gasket or something worse. The water got into the electronics and also broke a pressure sensor. Or was it the other way around?

I needed to remove the tank completely, clean it and descale it to evaluate the extent of the damage.

Step 2: Refurbish the Tank

It turns out that the leak was from a tiny fracture at the base of the flange of the heat exchanger.

Typically for a high-end espresso machine with two water systems, this one has a large tank that generates the steam for the cappuccino (2L can make a lot of cappuccinos!) but that is too high a temperature for an espresso. The water for brewing espresso goes from the pump into a smaller tank inside the main tank: the heat exchanger. That is a cylinder mounted on a flange on the side of the tank. That flange is visible in the pictures from Step 1 and is where the leak initiated. Next to it is another flange where the heating element is mounted. The heating element was missing and we will see why in a second.

The tank has to be removed, which means disconnecting all piping and removing it from the frame. I took plenty of pictures because of the complexity of the piping and of the wiring. While the schematics of the piping is available online, the wiring is a guess and I had to draw it by hand to make sense of it.

Once completely stripped, the tank needs a deep cleaning and descaling. The descaling is relatively simple: drop it into a bucket of water with a couple of descaling tabs. Since I already stripped all the copper piping and fittings, I dropped them in the bucket too, and left it overnight. It is important to ensure that most of the scale is gone from the inside too and that may take a couple of cycles of cleaning and descaling.

With the tank clean, the actual origin of the problem becomes clear: over-pressurization. The two flanges on the side are, in the original design, almost parallel. The heat exchanger and the heating element run inside the tank for about 3/4 of its length. Perpendicular to them, a water level sensor drops from the top and ends in the space between them.

The tank got too much pressure, probably because of the failure of the pressure regulator. That bent the side and rotated the two elements until they touched each other and touched the level sensor. That stopped the machine from working. It also made it impossible for the heating element to be removed, since unscrewing it breaks it. That is probably why the element was missing.

To refurbish the tank, the two flanges must be shaped back into their original angle. I fastened a long lever to a screw that fits the two threads on the flanges (they are the same thread, fortunately). It is important to fasten the tank on multiple place to ensure that bending the flanges does not deform the tank. The flanges are quite strong. It is a long series of trials and tests. Bend a bit, check for fractures, check for the angles of the two elements, bend more.

Once the geometry was correct, I proceeded with the epoxy repair. The bending did not create further damages but it is still a good idea to apply the epoxy to the entire areas around each flange, internally and externally. In fact, because it is a pressure tank, the epoxy inside is the one that counts.

I used a two-element, high-temperature epoxy compound for copper. The most important part is ensuring that the surfaces are absolutely clean and descaled. Outside, that is easy. Inside, it takes a lot more caution. Make it into a worm-like filament and press it strongly in place. Particularly inside, it is important to fit all contours and avoid sharp corners. Outside, I was quite generous in the application and covered both flanges entirely including the space between them.

Once cured, I sanded to smoother the surface.

Step 3: Put the Piping Back Together

The rest is like Lego. Put it back together following the pictures taken during the disassembly.

Fix the tank to the frame and install the pump. Add the piping to the pump and to the front elements (brew group, hot water, and steam). Install the safety valve and the anti-vacuum valve. Install the thermostat (better get a new one for about €5), install the pressure sensor and the pressure actuator (after testing for function.) Connect the two manometers in front. It turned out later that one of the manometer was broken, but I was able to replace it without taking everything apart again.

The piping schematics is readily available on the internet.

Step 4: Rewire the System

In this step, it appears quickly why it is important to take extensive pictures during the disassembly. Whoever took this machine apart and put it back together before me did some mistake in rewiring which fortunately did not damage the machine. The electronics sit in a protected niche on the bottom and consist of a black box with 9 connectors and one large relay that drives the heater.

A sticker on the black box has some indications (in Italian) about the wiring, which is not nearly enough, but helps. The other electric elements are the two switches and the two lights on the front panel, the pressure sensor, the pressure actuator, the pump, the level sensors on the tank, the thermostat on the tank, the level sensor on the reservoir and the power cable. Not super complex, but still a bit of a cable jungle.

There are some scattered electric schematics on the internet, but I could not find anything directly related to this model. I had to relay on the pictures taken when disassembling and on my own basic understanding of electronics.

Step 5: Clean and Descale the Brew Group

This is relatively easy albeit tedious. The brew group is complex and it accumulates scale easily. I took it apart completely and left the inner parts in a descaling bath for a couple of days. I had to manually scrap some of the scale. And replace a couple of gaskets for less than €10.

Put everything back, add the reservoir in the back and turn the machine on for a first pressure test.

Step 6: Test, Tighten, Adjust, and Enjoy the Coffee

I ended up adding a thermal blanket to the tank in order to lower my electricity bill and also make it come up to the right temperature faster.

On a first test, I went around the different fittings and tightened a few with minimal leaks. After three days of turning it on for a few hours, brewing a couple of coffees and cappuccinos, all mechanical parts were ok.

Last thing is the adjustment of the pressure, which is done by turning the screw on the black pressure switch mounted on the side of the tank.

After that, I could install the enclosure and place the machine back in my kitchen.