Crazy check... Am I nuts?

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sprint jinx
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#1: Post by sprint jinx »

Just a check in here to run my idea past the lever hobbyists here. Before I get in too deep money or time wise, I want to hear advice on how to best perform the following espresso mash up.

What I have is parts of several machines and I am trying to merge them together. The best of both worlds, in my opinion, is the thermo control of an HX loop along with the spring lever group pressure delivery.

I had a working Azkoyen machine, from Spain, and it has a robust 1 gallon boiler, and it is a heat exchanger setup, with just a single fat tube running diagonally through the copper boiler, top to bottom. There are many ports on it, but no sight glass, currently. The element is setup for 120, but 220 is available by swapping. I have either plugs available at the install site. The machine's solenoids failed, and I never really liked the pressure from the rotary vane pump, which I tried to restrict. Anyway, the machine has been stripped, cleaned and its ready for re-assembly.

The other end of the machine is going to use an old lever group from Conti. Its in great condition, cleaned and ready. I also have two steam wands, a hot water wand, and sight glass and portafilters all from the same machine. Everything with them is in excellent condition.

My first step was to ponder the merging of the water plumbing between the boiler and the lever group. The hx boiler has a thermosyphon loop setup, with long copper tubes running up to the group head area, where they have side by side, BSPP 20mm male fittings. The previous group head allowed for a hot water from the top of the boiler's heat exchange tube to pass between the two pipes internally, and then flow out of the colder tube to the bottom of the boiler where the HX port is.

So, I have one custom part so far. Its an adapter puck that is a lead free chunk of bronze, that I had milled out on a cnc machine. I drew up the plans for it in CAD and passed on the 3d file as well as a 2d copy as a pdf to have it made. It has the bolt pattern of the lever group around the outer perimeter to bolt up to it, and a dipper like cavity on the group side. On the boiler side, it has the two ports ready to accept the hot and cold feeds from the HX tubes. I have included pictures at this point to better describe the intent. Note that in the picture, the adapter puck has been put on backwards, the large cavity in the first pic should face the lever, and the side by side ports should face the boiler.



So, the idea here is that the HX water would use the ports on the bronze puck, and mix in the cavity, and create a thermosyphon loop there, constantly heating the puck, which is mated up to the group. The inlet hole of the lever group is open to accept water from the cavity. Normally, there is a long elbow of copper that reaches far into the boiler, like on a Prestina, so it sucks water from within, like a straw. In my setup, the water is alot closer to the lever group, but the same principal applies for a low pressure feed towards the coffee.

The next steps are to consider the frame of the machine, as it will have to withstand the weight of the conti lever, which is no joke. There is a single rib of steel with the matching bolt pattern on the bronze puck, they line up perfectly, which was the intent. I'm fairly certain that the rib will need additional bracing to combat the pull forces of the group and lever. I have considered T slot extruded aluminum as an alternative frame option, and totally ditching the current frame.

Beyond that, I have lots of more complicated steps. I have several coil heated silicone jackets that I could wrap the bronze puck with, and with some PID's thrown into the system, they could be actively controlled for setting the heat. Or, I can drill holes into the puck and use cartridge heaters, again with PID's.

The boiler will need alot of additional plumbing. My plan is to use a PID to control its main element. But, the issues of maintaining the water level has choices. I could use a stop cock valve and add water from my house pressure in a manual way. I could also use one of the ports on the boiler with a dip tube to electrically control the water level, as it was done previously on the machine. Id prefer manual. I might consider a switch driven solenoid valve, but I don't love them. I need water to enter into the HX, as well as replace the boiler tank, as they are separate tanks.

I have a very nice sight glass setup, with hefty brass end caps that are threaded. I would need to braze in ports for these in the copper boiler. That would not be easy, but it could be done. The glass would have to be visible to the user, as well.

I'll stop here, this is plenty of food for thought. Thanks for reading.

more pics!


larrbo
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#2: Post by larrbo »

Interesting! I don't think it's nuts at all...

For reference, the "Australium" was a heavily modified Londinium that used a rancilio silvia boiler feeding a commercial hx grouphead, which was connected to a separate boiler which fed the rancilio boiler/group, as well as providing steam and a hot water tap.



Build link is here:
https://coffeesnobs.com.au/brewing-equi ... ution.html

Your adapter puck essentially does the same thing, albiet with a dipper commercial group instead of an hx version. With enough pressure in the large boiler, you could feed your adapter puck to pull a shot. I do think that your adapter puck would need an additional heat source though. If you did it this way, you wouldn't even have to worry about plumbing the big boiler, just depressure the system and fill it from the top.

Keep us posted! This looks like a fun project.

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FotonDrv
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#3: Post by FotonDrv »

Both of these projects are good ones. The modified Londinium looks like it could be very temperature stable, is this true?
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Almico
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#4: Post by Almico »

I use a Victoria Arduino Leva at my coffee bar and I concur, a lever / Hx set up is ideal. I don't know why modern home lever manufacturers haven't caught on to this. Why all the hassle of dippers/thermo-syphons and variable pumps when you can just add a pressure regulator to the mains and get any pre-infusion pressure you want, at least for plumbed-in setups. Best of all worlds in my opinion.

Marcelnl
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#5: Post by Marcelnl »

why only with plumbed in setup, should be possible to add a pressure regulator inline after a rotary pump used to fill the boiler with any water you want to use. Actually something on my list to try for the Urania.
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JohnB.
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#6: Post by JohnB. »

Almico wrote:I use a Victoria Arduino Leva at my coffee bar and I concur, a lever / Hx set up is ideal. I don't know why modern home lever manufacturers haven't caught on to this. Why all the hassle of dippers/thermo-syphons and variable pumps when you can just add a pressure regulator to the mains and get any pre-infusion pressure you want, at least for plumbed-in setups. Best of all worlds in my opinion.
I must of missed it. What is "all the hassle" with using a dipper?
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Almico
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#7: Post by Almico »

Just wanted to get your dander up, John :D

But seriously, I'm in the market for a new 3gr lever. I would love a Bosco, but I won't give up the Hx. It makes for boiler independent, set it and forget it preinfusion. With a staff of 19-21 year olds, the simpler the better.

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JohnB.
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#8: Post by JohnB. »

I can see the pi advantage in a cafe but what is required to raise the shot water a couple degrees if you are going back & forth between your blend & single origins that might benefit from a higher temp. Can you do this on the fly as you would with a dipper or do you have to bump up the boiler setting. Flushing the hx would cool the group wouldn't it?
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Almico
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#9: Post by Almico replying to JohnB. »

Yes, that's another advantage of the Hx. There is no real flushing pre-shot. The brew temperature is fixed by the boiler pressure. In my situation it's perfect because I never change coffees. I dial the boiler in to my espresso, and since I roast it, it's always the same.

If I were to change coffees frequently, I would probably dial the boiler in hotter, and then use a short flush to cool it off for darker roasted coffee.

I also like that I'm not brewing coffee with boiler water.

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JohnB.
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#10: Post by JohnB. »

Almico wrote:Yes, that's another advantage of the Hx. There is no real flushing pre-shot. The brew temperature is fixed by the boiler pressure. In my situation it's perfect because I never change coffees. I dial the boiler in to my espresso, and since I roast it, it's always the same.
The idle brew temp is fixed by the boiler pressure on a dipper also. Mine idles at 198*-199* if the room is in the low to mid 70's. If I want it hotter each second of a pre prep warming flush adds 1*F to the shot temp. No thermosyphon stalls with a dipper! :D
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