Two more improvements: the water feed hose and OPV return hose have been replaced with new tubing.... and a water softener mini-cartridge added to the reservoir.

I think I'll sell the second one. As renewed as this one is, I no longer feel a need to have a spare on hand. Though I'd also be tempted, if a market aside from myself could be identified, to purchase some of the 'parts' machines out there and renew them. Would not add the gauge to them though. That's too big an undertaking to make worthwhile.

EDIT: operating note. First time I've left the machine on for over an hour. The Auber SSR is showing a temperature of 106. That's the highest I've seen, but it's nowhere near the stated operating maximum of 158. So I think my arrangement is doing ok.

You can get a naked portafilter for it or perhaps remove the spout part if possible, if cleaning portafilter is hassle, but for me I just let hot water through it.
My machine came new with pro stainless steam wand & espresso basket out of the box, and was surprised because thought they all come with pressurized.
I posted few days about possibility of adding additional preheating pipe or Uboiler like this that's either pid controlled or that would start only when brewing to increase brew temp stability.


Someone added similar JBoiler to gaggia and PID both boilers.

Also this video might help to understand the brew head spring and how it affects both lower & upper pressure threshold. http://www.youtube.com/watch?v=yrB2Dr-6q9s

I have cheapest delonghi and mazzer major, but I don't remember drinking better coffee than what I am getting from this machine anywhere, despite few white drops due to small boiler which that preheater might fix, but I probably won't bother, because the taste result I am getting is all I need, velvety dense espresso. It's true there are days that it has sour tone, but that's when I don't let the machine and everything touching water to preheat enough, giving it 5 minutes only to heat up or when I bought it it was tangy bitter when I didn't release steam in the boiler before extraction...since then I have specific temp surfing technique switching steam shortly while in preinfusion. Also during preheating I am running hot water from boiler few times to heat it up thoroughly incl portafilter...

I don't think he's joking. If that is parody, it's going to be misleading a lot of people.
That's got to be one of the dumbest takes I've seen in a while. The video shows nothing more than someone intentionally stalling a pump with and without the pressure-drop of the brew valve (at more than one tension). Then running it with a leak at the gauge to prove he can compensate. The pump is already weakened (stalling at 14.5 Bar), But if you have enough faith, maybe stalling a pump isn't bad for it. maybe an OPV isn't a good idea.

@marteccino: I already have both a bottomless and an unpressurized double-spout portafilter for it. And I'm beginning to think that perfect temperature consistency is an arbitrary goal, not necessarily relevant to my desired result (which is not graphs on a website, but a delicious cup of espresso). I do like the idea of that warming loop though from a strictly design standpoint, though with the SSR in the machine there's no room for additions.

JRising wrote:I don't think he's joking. If that is parody, it's going to be misleading a lot of people.
That's got to be one of the dumbest takes I've seen in a while. The video shows nothing more than someone intentionally stalling a pump with and without the pressure-drop of the brew valve (at more than one tension). Then running it with a leak at the gauge to prove he can compensate. The pump is already weakened (stalling at 14.5 Bar), But if you have enough faith, maybe stalling a pump isn't bad for it. maybe an OPV isn't a good idea.

I just come across it today too and posted it for others to review. I read already read few conflicting opv vs brew spring vs flow rate takes that I still don't have a clear idea about. All I know spring holds the flow up to ~5bars and OPV limits pump at some 11-13bars to not overshoot.
I read that brew valve spring also limits upper pressure which is what guy in video was probably trying to prove.

Then there is this blog post with this flow measurements

10.4 seconds per ounce at 7.5 bar (170 ml/min)
9.1 seconds per ounce at 5 bar (192 ml/min)
3.3 seconds per ounce at 0 bar (530 ml/min)

More on that here website.https://benkrasnow.blogspot.com/2010/11 ... i.html?m=1

But again I can't come up to the conclusion how it all comes together. One might think that grind will ultimately dictate pressure & flow control, but then not sure if this spring mechanism affects it differently than machines that have three way valve.

Ah, yes...

The brew valve.

These are a bit annoying, because they have a known cracking pressure, and then a relatively unknown (but measurable with a dimmer mod) flow to back pressure curve.

So, the deal with these guys is that there is always a pressure drop across the brew valve, and it is never less than the cracking pressure. So if it takes 5 bar to crack the valve, the brew pressure gauge will always read at least 5 bar higher than what the puck sees. Thus, if you want a 9 bar extraction, and you've verified that it takes 5 bar to crack the valve open, your brew gauge should read at least 14 bar.

You could pretend that the pressure drop is always 5 bar, and get along just fine. But it gets dicey when the flow rate is changing.

This is where measuring the water debit at different flow rates with the dimmer mod can help illuminate the situation. If it takes 5 bar to get a couple drips out of the brew valve, and 6 bar to get 1ml/s and 8 bar to get 3ml/s, etc... you can map out how the pressure is falling across the brew valve based on the flow rate into the cup. In this case, it would be like a gicleur on steroids.

But, if the brew valve is magical (it may well be) and simply cannot provide more than 5 bar back pressure, no matter what, then you can subtract 5 bar from your boiler-mounted pressure gauge and call it a day.

All this said, there is really nothing wrong with not knowing the exact pressure at the puck, since knowing the exact pressure in the boiler gets you most of the way there, and is a relatively repeatable measurement. What you can say with certainty is that the brew pressure is never more than what the pressure gauge reads, and just knowing this is enough to get repeatable shots that are tasty. Knowing the offset is never less than 5 bar or whatever helps you estimate a good starting place, but whether 9 bar on the gauge is 4 bar or 6 bar at the puck is rather irrelevant. What matters is whether or not doing whatever it is you are doing, based on feedback from the gauge gives you tasty results.

I agree with John that the video only shows the pump riding on its curve. Not sure how that's helpful. It would be like cracking the steam wand open until the portafilter mounted gauge shows 9 bar and somehow thinking this is meaningful... the only value-add test I can think of would be what I described, where different flow rates are used by dimming the pump and then measuring the pressure drop across the brew valve. But even then, you would have to k ow the instantaneous flow across the brew valve to make the results of that test useful if they were at all dynamic, and I strongly suspect they would be.

Cheers!

- Jake

@Jake_G: Ok.... so my brew valve is passing water at just over 2 bar on my pressure gauge (teed in right after the OPV and before the boiler). You're saying it should read 11 bar in order to be pulling a 9 bar shot? And so I should also then have the OPV max out at 11 bar?

You know...

I wrote that whole post with 2 bar and 11 bar, based off of my gut, and then reread the post before it and tweaked everything from 2 bar and 11 bar to read 5 bar and 14 bar.

So...

Yes. Exactly that

Cool. Because I'd read a few things based on having seen marteccino's post, arrived at that conclusion, and adjusted my OPV accordingly. On two shots this afternoon the gauge maxed at 11.5 bar. And the shots were great, with wonderful crema. Glad to know I'd absorbed the information correctly and made the correct adjustment.

And yet one more improvement is underway. I located a 3/8" thick piece of steel. A local shop is cutting it to 8x10" for me for a few bucks. I will then grind the edges smooth and rounded, paint it, and mount it on the bottom of the ViaVenezia. It will add another six pounds to the machine, thus stabilizing it a bit more and making it even easier to lock in the portafilter without having to hold the machine.

Ok read this few days ago through my dislexia like symptoms but does this mean that if spring resists initial 5 bars than all the pressure generated equals minus 5. So if pressure that ppl mounted on line into the boiler shows 8 or whatever, the puck is hitting minus 5 which is 3? Yeah don't think that's the correct analogy.
My impression is that even tho the initial pressure requires 5 bars threshold, any consequent pressure generated by pump over that 5 bar equals what's hitting the portafilter since that small 5 bar spring no longer creates that back pressure perhaps once that threshold is broken....
If it was generating that 3 bar it would be noticeable in the taste, but ppl compare these machine made espressos to fully fledged commercial or consumer made espressos. Example one YouTuber having similar machine based on same mechanism has richer better coffee on it than on gaggia or even the spaziale Vivaldi.