I've been drinking espresso for many years (more than fifteen) and I've owned a super-automatic machine (jura E8) for the last six or seven. I recently decided to "upgrade" to a semi-auto machine. I bought a Baratza Vario and a Rocket Cellini Classic. Now everything that I do on these machines creates sour shots. I've read tons of info, watched tons of videos, and tried everything that I could find to fix this. I've tried grinding finer, I've tried grinding coarser, I've tried more coffee, less coffee, harder tamp, lighter tamp, start-dumping, dark-stopping, center-cutting, pulling a blank shot to cool the water down, running the hot water valve to heat the water up, timing the shots, ignoring the timer, etc.

The shots are ALWAYS sour. I got the machine on Jan 2, and I've pulled around 30-40 shots through it. Of those I've probably been able to drink two. The coffees that I've tried, in order, are "Velton's Bonsai Blend" (which came free with the machine from seattlecoffeegear.com), Starbucks Espresso beans (because I ran out of Velton's), and now PT's Southpaw. All except the starbucks were fresh roasted.

At this point i'm starting to doubt my own judgement, starting to think that perhaps I don't know what espresso is supposed to taste like. Also, I hate to admit this, but the "best" of the shots that I pulled were from the Starbucks beans.

spuriousdata wrote:I've tried grinding finer, I've tried grinding coarser, I've tried more coffee, less coffee, harder tamp, lighter tamp, start-dumping, dark-stopping, center-cutting, pulling a blank shot to cool the water down, running the hot water valve to heat the water up, timing the shots, ignoring the timer, etc.

Why do you think running the hot water valve will heat the water up?
What's the pressurestat set to? (what is the boiler pressure)

Because, from what I've read/seen, running it until the pump clicks back on will cause the boiler to come back on to heat the water up and when it clicks off it should be at the top of the temperature 'window'. I have no idea what the p-stat is set to or how to find out. The machine has only one gauge on it for the boiler pressure, which is consistently between 1.0 and 1.2 bar

The reason it causes the heater to kick on is because you are depleting water from the boiler so the machine refills it. Because the flood of room temperature water cools the boiler, it causes it to call for heat. You aren't heating it any more than it would be soaking at the setpoint. Sure there is a deadband but on an HX its impact is small. Try adjusting the pressurestat up, although if you are at 1.2 bar it's probably not the boiler temp; you could hit the over pressure relief valve if you boost the pressure too much.

Might be worthwhile to do a double check on pressure with a gauge on the steaming wand, and/or measure the temp of water from the group head into a foam cup.

After the machine has been idle for a while, does it spit'n'hiss/'water dance' when you lift the lever with no PF locked in? It should (as the water in the HX pipes get overheated).

How long are you flushing, if at all, before the shot, and how long do you wait after the flush?

FWIW, I found the Velton's left something serious to be desired when I got a bag with my Cellini Evo v1. (It's boxed up in search of a new home now after 2 years of good service.) Regardless, I usually only got sour shots when I flushed too much and/or didn't give it enough recovery time (which was often ). The other main cause was if I didn't wait long enough for the machine to reach temp initially.

If you keep your Cellini, I highly recommend getting erics's thermometer mod. However, since you're in diagnosis phase, have you tried the styrofoam-cup-temp-check to see what the water temp looks like? If you aren't getting any HX water dance, then I suspect something is up with the machine itself (gauge, thermosiphon restrictor, ?).

Now to question your palate if nothing above helps If you flush a lot of water then immediately lock on the PF and pull the shot, does the sourness match what you were seeing after sitting idle? There should be a noticeable difference in taste and extraction!

Any extra notes on the extraction would be helpful too -- how's the crema look? how quickly is it blonding? Just more info of any sort might prove useful!

Well, one thing i've noticed is that the boiler cycles on and off very frequently. If you just stand there and watch it, you can see the gauge slowly drop from 1.2 to just below 1.0 and cause the boiler to kick on. It happens about every three to five minutes. I'm not sure if that's normal.

That's probably just the pstat deadband. That much seems normal as long as it is keeping it in the "right" range.

redpig wrote:After the machine has been idle for a while, does it spit'n'hiss/'water dance' when you lift the lever with no PF locked in? It should (as the water in the HX pipes get overheated).

I've read about this (on this site, I think) but I've been unable to discern it. This is the reason that I've tried pulling a blank shot.

redpig wrote:How long are you flushing, if at all, before the shot, and how long do you wait after the flush?

I flush for about ten seconds when I've tried this method then removed the pf and the 'wait' time is as long as the grinding, tamping, and remounting of the pf take.

redpig wrote:FWIW, I found the Velton's left something serious to be desired when I got a bag with my Cellini Evo v1. (It's boxed up in search of a new home now after 2 years of good service.) Regardless, I usually only got sour shots when I flushed too much and/or didn't give it enough recovery time (which was often ). The other main cause was if I didn't wait long enough for the machine to reach temp initially.

In the beginning, I wasn't flushing at all, and I was still getting sour shots. The machine warm up time was ranging from 20 - 45 minutes.

redpig wrote:If you keep your Cellini, I highly recommend getting erics's thermometer mod. However, since you're in diagnosis phase, have you tried the styrofoam-cup-temp-check to see what the water temp looks like? If you aren't getting any HX water dance, then I suspect something is up with the machine itself (gauge, thermosiphon restrictor, ?).

I'll look into getting a thermometer mod and check the temp in a styrofoam cup.

redpig wrote:Now to question your palate if nothing above helps If you flush a lot of water then immediately lock on the PF and pull the shot, does the sourness match what you were seeing after sitting idle? There should be a noticeable difference in taste and extraction!

I'll go try this now.

redpig wrote:Any extra notes on the extraction would be helpful too -- how's the crema look? how quickly is it blonding? Just more info of any sort might prove useful!

The crema is thick and dark, but if I let it sit in the up for more than a few minutes (say more than five), the crema all but disappears. It's honestly hard to discern any flavors other than really nasty sour.

redpig wrote:That's probably just the pstat deadband. That much seems normal as long as it is keeping it in the "right" range.

It keeps it in the 'green' area on the gauge.

Try flushing with the PF off after the machine has been sitting for a few minutes. It is much harder to hear/see the water dance with the PF locked in.

As to warm up, 20 minutes pretty much always got me sour. The grouphead wasn't warm enough, but 45 was usually enough.