Just a quick question... I promise to post a complete set of photos for this later but I'm rebuilding a rancilio S 20 Midi De. I've gone through the teardown and cleaning and am now doing the re-assembly, hopefully to be complete tonight but we'll see what happens. The machine (pictured pre-rebuild):


I got it from a coffee shop via ebay, for $400. Unfortunately it's really hard to score a good deal in Canada due to the lack of density and in my area (Calgary), we're a bit behind larger metropolitan centers in terms of espresso style coffee. Anyway, I definitely will post some rebuild photos. It was a complete teardown to the frame and because I wanted to keep this cheap, I didn't powder coat, just sprayed it with spray paint. The only other improvement made was the addition of an insul-brite boiler insulation blanket. I bought enough material from a sewing shop ($9), made a nice velcro seam for removal and because it's kind of a random-fiber material, just cut out holes around the necessary protrusions.

At this point in the rebuild, I have the group headers in, the pump installed and the boiler installed, with the insulation on. No piping at all. During the rebuild, I treated the whole thing to a citric acid bath, twice over. I had tons of scale in the boiler and the exchangers and everything was nasty, especially the gicars which are now clean but weren't dosing correctly when I bench-tested it before the teardown. I have new gaskets for the boiler main gasket and the heating element gasket (both teflon) and have treated the group headers to new gaskets and will also replace the o rings on the gicars and the o rings on the group header valves.

So along to my question... I removed the heating element to give it a dip in the acid bath too, keeping all the wiring intact, just dipping the elements in the bath which worked very well. Unfortunately, I have a connection issue, best described through the diagram below:


When I was taking the assembly apart, I unscrewed part number 31 from part 33. Although it doesn't show it well in the diagram, the stainless tube (part 29) is actually not continuous and part 32 is, according to the rancilio parts diagrams, a teflon tube which covers the transition. My little teflon tubing (about 3/8" or 8 mm long) actually split along it's length as well. I know the tubing (part 32) looks more like some kind of pressure sealing gasket but it's not, it's just a tube that fit snugly over the two sections of stainless piping to line them up. I can't find a replacement part anywhere but I was actually thinking of using teflon tape to replace this, packing the whole joint pretty tightly before screwing parts 31 and 33 together.

Any thoughts on this? I'm assuming the teflon tape will seal the entire cavity up well but it's not ideal because of the high temperatures at the heater. Any advice would be welcome.

Post a picture of that part if you can. I think I may know what you are refering to. It sounds like a teflon sleeve of some sort. I have one on my Pavoni Pub that my water level probe slides through.

Just a quick update. I decided I was going to try the teflon tape last night and set about re-assembling the heater. When I did though, I carelessly broke the tubing over which the transition piece fits (the tubing running into the assembly from outside the boiler. Initially, I even thought that the tubing was thin stainless, but it turns out it was just really dull chromed copper. I had just enough tubing to straighten the section out, re-bend it and get the tubing in the hole through the bolt center hole (part 31). I fired up the propane torch, added some flux and soldered the tube to the threaded brass bolt (which was tightly screwed into the heater beforehand). I honestly didn't want to do this but I needed to progress and try and get the machine running. This means, though, that if it needs to be removed in the future I'll have less flexibility to do so. What I actually intend on doing (long term) is cutting the copper tubing about an inch from where it enters the heater, adding a threaded transition fitting and coupling it that way. This would allow for easy removal of the heater, rely on threaded seals like the rest of the machine and keep plastic out of the water system. We'll see how a test run goes today.

Tom, thanks a great deal for the comment back. I'm actually going to post the rebuild photos on a separate thread over the next couple of days, from start to finish. I will pay particular attention to this spot, it seemed to be the biggest problem I came up against on the rebuild and I expect that because the whole assembly is so flimsy, others may find the same. I guess Rancilio didn't intend on a ton of work on it but the rest of the machine is so rock-solid, it couldn't have hurt to throw in one more fitting.