My brand new machine pressure gauge reads quite low - I think peaking at about 1 bar and then dropping to 0.9.

I'm going blind searching various forums for precise instructions on how to adjust (if required). Do I have to remove the top plate or is there, as I recall in some lost post, a way to reach from the outside.

Help/Pictures much appreciated.

wim

Why do you think it needs adjustment? A boiler pressure of 1.0 bar doesn't sound unusually low (brew pressure of 1.0 bar would be very low). You can see the Giotto's pressurestat in this photo:


It's the white switch / beige plastic housing / metal ring perched atop looped copper tubing

I don't believe you can access it without removing the top panel. The thread How to adjust Bricoletta boiler pressure offers instructions and links that apply to your Giotto.

Thanks for the quick response. Your question about why I think it is low is a good one. I guess it comes to not having a precise point of reference and thereby being force to make some assumptions that might not be valid.

When boiler pressures are typically cited for this class of machine, does the number refer to the point at which heating will cut off - eg. the high point. My gauge appears to peak at 1.0 bar. Reaching this point is coincident with the "kettle boiling" noise ceasing. Then the pressure drops to about 0.8 bar. This would make sense to me if the "dead band" is 0.2 bars. Though it would also be reasonable if there was some overshoot.

I typically see numbers between 0.9 and 1.2 cited with the later generally being consider too high. The table at https://www.coffeegeek.com/files/226/ specifies 1.1 bar, and I am taking on faith that this is likely a common/desired setting.

While I realize that I can likely get similar shot quality with any setting between 0.9 and 1.1, as a newbie, it would be helpful to have a value which is typically so that flush times and volumes are comparable to those I read about.

And this discussion is a lot easier than trying to deal with the fact that I'm have a devil of a time determining when the "water dance" ends.

Actually, in the table I referenced above, it says

If your boiler pressure is 1.1
bars (that is, the heating element will kick in once boiler pressure falls below 1.1 bars)

.

Based on the observed behavior, eg. going from 0.8 to 1.0, that my pressure is set to 0.8 ?

Or the gauge isn't accurate.

Thoughts?

wimpee wrote:When boiler pressures are typically cited for this class of machine, does the number refer to the point at which heating will cut off - eg. the high point. My gauge appears to peak at 1.0 bar. Reaching this point is coincident with the "kettle boiling" noise ceasing. Then the pressure drops to about 0.8 bar. This would make sense to me if the "dead band" is 0.2 bars.

The quoted boiler pressure is the top of the cycle when the heating element turns off. A peak of 1.0 and deadband of 0.2 bar sounds eminently reasonable.

BTW, Abe recently brought his Giotto out of storage. I wonder if he still uses flush charts you linked above (I never have).

Abe Carmeli wrote:The solution is a flush chart. But how much to flush? The quantity depends on how long the machine has been on, and idle. The flush brings down the brew water temperature to around 201 degrees f. You wait 25-30 seconds after the flush to allow the Heat Exchanger to recover the temperature to 202-203 degrees, and you pull your shot.

I'd add that heavy HX groups that have been idle for a long time are less predictable on the first flush. Applying Abe's charts, I think you'd get much better results if you followed his "long idle" flush amount when necessary, wait a few minutes, then follow his recommend flush amount. Otherwise the first shot after a long idle flush will tend to run hot.

Wimpee- congrats on your new Giotto. My gauge reads 1.05, so it sounds like we're in the same ballpark. I had a hard time figuring out the water dance procedure as well. What works for me is to pull 150ml, let stand for ~50 seconds, and then pull the shot. I use extra baskets and have removed the portafilter retaining spring from the pf; so I have my baskets filled and tamped ahead of time. For ensuing shots, I pull on the minute. The intervening ~35 seconds I use to wipe the dispersion screen. Hope this helps!

this may help you decide on where you want boiler pressure to be.

giotto premium and krups thermoblock shootout

to summarize, 0.6-0.7 bar boiler pressure is ideal if you dont want to flush, and dont mind weak steam.

right now, 0.9bar seems good for me. i havent tried 0.8 though. could be best of both worlds, but i doubt that not flushing and still getting good steam is possible.

Perhaps this deviates from my original topic slightly but is perhaps at the crux of my concern.

Could a couple of people please describe their boiler gauge behavior from cycle to cycle starting from the bottom.

My observed behavior:

1) Gauge reads 0.8 and there is a click sound and heating begins as evident by the "kettle working" sounds. (Anyone have a technical term?)
2) Gauge climbs steadily to 0.95 bar. The "kettle sound stops"
3) Within 1 to 2 seconds, the Gauge reads 0.98 bars. (Just on the left edge of the 1.0 mark)
4) Over the next thirty seconds, the gauge drops slowly, but visibly and consistently until returning to step 1.

I need to update with precise timings later when I'm in front of the machine.

wimpee wrote:1) Gauge reads 0.8 and there is a click sound and heating begins as evident by the "kettle working" sounds. (Anyone have a technical term?)

controller activates heating element?

2) Gauge climbs steadily to 0.95 bar. The "kettle sound stops"

i only hear a kettle sound when the machine is cold and there isnt any steam in the boiler. kettle sound to me is whistling or air releasing from vacuum valve (i think its called) . otherwise, i just hear what sounds like heating water. 0.95bar is what i consider your normal operating pressure.

3) Within 1 to 2 seconds, the Gauge reads 0.98 bars. (Just on the left edge of the 1.0 mark)
4) Over the next thirty seconds, the gauge drops slowly, but visibly and consistently until returning to step 1.

I need to update with precise timings later when I'm in front of the machine.

is the coffee good? im not sure of your problem.. or, is it just a concern? if the coffee is good, who cares what it reads. if you see it drastically change, then worry, as it may indicate a problem..

wimpee wrote:Perhaps this deviates from my original topic slightly but is perhaps at the crux of my concern.

Could a couple of people please describe their boiler gauge behavior from cycle to cycle starting from the bottom.

My observed behavior:

1) Gauge reads 0.8 and there is a click sound and heating begins as evident by the "kettle working" sounds. (Anyone have a technical term?)
2) Gauge climbs steadily to 0.95 bar. The "kettle sound stops"
3) Within 1 to 2 seconds, the Gauge reads 0.98 bars. (Just on the left edge of the 1.0 mark)
4) Over the next thirty seconds, the gauge drops slowly, but visibly and consistently until returning to step 1.

I need to update with precise timings later when I'm in front of the machine.

What you describe is normal operation. Some pressurestats have a tighter deadband (your deadband is ~0.15-0.2 bar) and some pressurestats have an adjustable deadband (most do not). What you have is perfectly acceptable, but some folks desire more precision. I think you should be fine.

When people report their boiler setting, they should be reporting the top of the cycle or the highest point. I would use it as is, and try tweaking it up later if you still think it needs it. (It is also possible that your boiler pressure gauge does not read correctly, do we have a reason to think so?)

What is your difficulty with the "water dance"? Can you not see or hear it? Can you post a video?