Hi!
I just bought an old machine by chance. I have just had a toy machine before (super giada) so this is my first decent(i hope) machine. I don't know so much about espresso machines, but i am an engineer and the mechanics seems pretty simple so i guess i can learn. Plan was to wipe it off and descale by backflushing. Yesterday evening i was plugging it in my garage to do a test but it ended up with a complete disassembly. And now i have sent the panels and frame for powder coat.

On the top side of the heat exchanger, when i loosend the big tubes to the groupsets i found some washers that that i cant find in the drawings exploded views. The washers have small holes so i guess they are for flow restriction.
Should i have them there? could it be a modification by previous owner? Anybody seen this before?

The washers are on the close up picture on the boiler attached. i have taken them out from the coupling and put them on top of the coupling for a better view.

Thanks in advance!
/Andreas

Welcome Andreas!

Nice find on the machine. I have an S20 MIDI CD (manual version of your DE) and I love it.

As for the washers, you are correct that they are flow restrictors. My machine did not/does not have flow restrictors, but they can be a good thing. They are there to temper the idle temperature of the groups by limiting the convection flow through the thermosyphon tubes. Only way to tell if you need them is to pull shots on the machine with and without and figure out if the groups are too hot without or too cold with. Both conditions can be easily addressed with an appropriate flushing regiment, so the winner is the setup that gives you the right temperature with the least amount of fuss.

Given that you have the restrictors on hand, I would be mighty tempted to install a restrictor in one group and leave the other without. Then figure out if you prefer it with, without, or prefer having one group tuned hotter for certain roasts and the other cooler! Feel free to PM me with any machine-specific questions,

Cheers!

- Jake

Thanks Jake for the great explanation!
I haven't yet taken the group heads apart so i was wondering a bit about how the flow was going but your post cleared everything up. The bigger diameter tubes is only for heating group heads so now it all makes perfect sense! I will follow up on your advice and install the washer on one of the group heads. It was pleasure to disassemble the machine, every nut was easy to loosen with a nice click sound. Tonight i will proceed with descaling

The water for the shots comes through the big tubes, as well. The flow path goes from the pump, to the expansion and check valve manifold which supplies both of your gicar flow meters that sit atop the groups, then back down to the injectors at the bottom of the heat exchangers. This injects high pressure cool water into the heat exchangers, forcing the heated water in the thermosyphon tubes into and through the group when the 3 way valve hanging off the bottom of the group opens.

How was the scale buildup in the boiler?

- Jake

yes, of course! Then there is some already heated volume to brew from. But one question, my convection flow restriction washers is on the top side of the boiler. When brewing, i would think its better to have the cold water going the same way as convection so it passes through the heat exchanger before reaching group head. But with flow restrictors on the top side side, the water could have easier to pass in the opposite direction to the group head and maybe get too cold wile brewing? Wouldn't it make more sense to have the convection flow restrictor on the bottom connection of the convection flow pipes on the boiler?

Another question, Why is it a 3-way valve on the group head and is it really a 3-way? How does it work? i see that it has one plunger that can open up between the two holes in the group head, but when do water go out through the third port? i guess the third port is the one with jet breaker on?
Is maybe the third port connected to the output to the filter when solenoid is not engaged? so the filter pressure goes down when solenoid closes?

About the scale buildup i don't have any reference so i don't really know if its good or bad, but here's a picture of the boiler:
I have seen some horrific examples on the net for scale buildup but i don't think those pictures are good references for me.

Its mostly a thin hard black surface inside boiler that has been flaking. What could that be, is it also scale? Will the citric acid dissolve it or do i need mechanical scrubbing?
I have been soaking it over night with the recommended dose, 1 tbs per liter. I started with warm tap water but i haven't been heating it so its cold now. The solution gets a little bit green so i guess it also eroding some copper. Should i worry or just let it sit longer?
Br Andreas

Larsen2000 wrote:When brewing, i would think its better to have the cold water going the same way as convection so it passes through the heat exchanger before reaching group head. But with flow restrictors on the top side side, the water could have easier to pass in the opposite direction to the group head and maybe get too cold wile brewing? Wouldn't it make more sense to have the convection flow restrictor on the bottom connection of the convection flow pipes on the boiler?

If you pull your injectors out from the bottom of the heat exchangers, you will notice that they inject the water close to the middle of the exchangers. This forces water out of both tubes, with a preference for the lower tube, for sure, but there is a 1.5mm restrictor in the base plate for the sirai 3 way valves, so the flow is restricted regardless. I don't think the thermosyphon restrictors have much effect on the brew flow at all... Also, the water in the HX will be close to 235 degrees F, so favoring the bottom of the exchanger (if it did) would not likely get too cool, either way.

Larsen2000 wrote: Another question, Why is it a 3-way valve on the group head and is it really a 3-way? How does it work? i see that it has one plunger that can open up between the two holes in the group head, but when do water go out through the third port? i guess the third port is the one with jet breaker on?

Bingo. I have a good working model of the group in my build thread that shows the internal passageways. The spring in the 3 way valve keeps the pressure port at the center of the group sealed off and allows the port that goes to the group to be connected to the exhaust muffler (jet breaker, as you call it, but there is another part, behind the shower screen, that is technically a "jet breaker" ). When the coil is energized, it pulls the plunger in the valve down to seal off the exhaust port, which sends pump pressure through the group.

Your scale buildup does not look bad. You really need to heat the citric acid solution HOT to be really effective. Green is ok. I'm not sure about the black surface coating. I had a bit of that in my boiler, as well. I resorted to some light media blasting to clean up the element and internal surfaces, but my scale was MUCH worse...

Nice work so far, the machine looks to be in great shape! Make sure you pull the gicleur caps and install one in there if they are missing! Mine just had a gaping 8mm threaded hole where they should be... the caps are the large hex bolts above the socket head cap screws in the front of the groups. Factory spec for the S20 is a 0.5mm orifice.

Cheers!

- Jake

Jake_G wrote:If you pull your injectors out from the bottom of the heat exchangers, you will notice that they inject the water close to the middle of the exchangers.

I need to check that i have injector lines, i have no memory of seeing them while disassembling but i probably remember wrongly. I'll check tonight!

The gicleur caps, is that this one?


I don't have any restrictor inside and i cant find it on the parts diagram:


Really interesting read in your thread about pressure profiling! Nice job! I understand in some aspect the purpose of regulating the flow/pressure to the filter but i don't have the practical understanding of how it will affect the taste of the espresso. Here i have a huge knowledge gap to learn. I know its important to have the correct brewing temperature for the chosen roast, but i thought it was enough to have a constant 9bar of brewing pressure. And i thought that the pressure holding valve would keep the pressure at 9 Bar. If i install a gicleur, it will have a delta pressure related to flow and then it wont be 9 bar brewing pressure in the filter. I have learnt that you really know a lot about espresso and this machine and i am sure that you are right that the espresso will be better with the gicleur in place.
I've searched and found this thread: What the heck is a gicleur-jet for?!?

If you want to experiment with pressure ramp-ups, you can install a a manually adjustable needle valve at the pump head. Andy Schechter, a legendary coffee amateur, did this and was able to stretch out the shot's initial ramp to full pressure to 20 seconds. However, he found that the ramp up time made little difference in the quality of the shot. It just had to be long enough so the puck wasn't destroyed by too rapid a pressurization; if you get five seconds or more before seeing any flow, you will usually be fine in this department.

Is this the one reason? I would love to hear your opinion.
Do you know where to find a matching gicleur to buy?

Jake_G wrote: Your scale buildup does not look bad. You really need to heat the citric acid solution HOT to be really effective.

Wont it have the same effect if i just let it sit longer? Or is it better to heat it up? I'ts easier for me to have it sitting in the garage for a longer time (heated garage) than to bring it in the kitchen at home

Larsen2000 wrote: I need to check that i have injector lines, i have no memory of seeing them while disassembling but i probably remember wrongly. I'll check tonight!

Looks like you left them in the boiler. They thread into the bottom of the HX unions.

Larsen2000 wrote: The gicleur caps, is that this one?

Yessir. You correct that Rancilio doesn't show them on the parts diagram. But if you look up the group of ANY OTHER Rancilio commercial machine, there they are, right under the cap specifically meant for them

Larsen2000 wrote: Is this the one reason? I would love to hear your opinion.
Do you know where to find a matching gicleur to buy?

That is one of the big reasons. Our rotary pumps are BEASTS when it comes to delivering water to the puck. Typical flow through a puck is on the order of 100mL per minute and unrestricted, I get 700mL per minute to the groups with mine. The gicleur drops that down significantly, which is a good starting point to keep from obliterating your puck when you turn the pump on. I went a step further and placed a kill switch between the brew switch and the pump, but I would recommend you get yours up and running before toying with ideas like that

As for where to get one? I am lucky enough to live very near Stefano (http://www.espressocare.com) and he is extremely knowledgeable and helpful and I save on shipping since I can go pick up my parts in person. He will no doubt have what you need, but you may be better off looking for a supplier more local to you if there is a good one. Just ask for a Rancilio gicleur and make sure it has 8mm threads and you should be in great shape.

Larsen2000 wrote: Wont it have the same effect if i just let it sit longer? Or is it better to heat it up?

Arrhenius tells us that for every 10 degrees C we increase the temperature, the chemical reaction rate doubles. So, going from near boiling to what, 25C? That reaction is going to be SLOW in a cold garage... 1-2 hours at boiling turns to 2-4 -> 4-8 -> 8-16 -> 16-32 -> 32-64 (I'm only at 50 degrees C here!) You get the idea...

But yeah, if you have a LONG time to wait and check on the parts regularly, it will work, but not near as effective as a quick bath in a big pot.

Cheers!

- Jake

You're absolutely right about the injectors, they were there the whole time!


Thanks for the information about the gicleur, its helpful! I have found some places to buy them from, and here's some OEM partnumbers if anyone else is looking:
RANCILIO: 10060507, 10060603, 10060612, 23210016, 23212018
RICAMBI GARDOSI: R156

Also a tips to readers in Europe. I found a Polish site that have almost all pars for sale at good prices and its possible to search on oem partnumbers: www.gastroparts.pl
You need to register an account to see prices. They also have spare parts catalogs on the site.

I followed your advice about the heating. It seems to work good but i need a bigger pot at home


I brought some parts to work and used an heated ultrasonic cleaner with citric acid. Worked great!



Due to this effect, i couldn't help myself so i ebay-d a 30 Liters ultrasonic cleaner that will fit the whole boiler. I'm going to Italy on Saturday for skiing and probably some fantastic espresso. I'm eager to assembly it but i won't have time before the trip anyway so i might as well clean it all in the big ultrasonic cleaner when i'm back.
Cheers!

A couple notes on the groups:

I recommend doing a little polishing on the surface behind the shower screen as the matte finish on these groups makes them a pain to keep clean. I drop the shower screens once a month for my detergent backflush and oh how I wish I had spent the time to make that surface less porous and easier to wipe clean... Now it's scrub, scrub, scrub...

Second: consider modifying your jet breakers and installing flat head screws to secure your shower screens. Our machines have notoriously little headspace to begin with and having that big shower screen bolt crack your puck open is no fun. I just took my jet breakers to work and countersunk the holes to accept a flat head bolt. I got an M5 nut and clamped the stock shower screen against the countersunk jet breaker outside the machine so I didn't risk hurting the threads in the group. The shower screens easily take the shape of the countersunk bolt for a nice flat surface that doesnt hurt the puck. Alternatively, you can pick up a couple "flat shower screen" kits for a Silvia and they will work like a charm, but the prices are usually pretty steep for what you get.

Also, consider picking up an Eric's group thermometer and ask Eric if he can leave the probe loose from the display. Temperature management is critical and going by cooling flush sound and timing on these machines is a pain. It works, but they recover so fast your workflow has to be rock solid. Remote mounting the temp display on one of the groups where you can see it would be a huge benefit to you for consistency...

Great work on the rebuild!

- Jake