Espresso Smith wrote:"It's all in the cup" I have always said this and I continue to say it.

You have all mentioned that the temperature/pressure in the boiler is not affected by the altitude - this is true.
However, the water boiling temperature will affect the extraction of the espresso (the most common problem is the flash of boiling water and steam towards the end of the extraction, which destroys the crema).
Boiler pressure/temperature will affect water brew temperature and group temperature.
I read more than 10 posts on this forum from people that have high altitude problems with their espresso extraction.
Why are temperature sensors being installed directly on the group heads?
Because there is a direct relation between the boiler pressure/temperature, the group head temperature and the water brewing temperature.
Without going into all of the details of thermosyphoning, heat transfer, heat exchangers, group head mass, preinfusion, etc. there definitely is a challenge in extracting excellent espresso at high altitude! The 9 bar pump pressure/1.2 -1.4 bar boiler pressure/18-22 second extraction time should be erased from the espresso machine manuals.
I have tasted wonderful espresso extracted at 16 seconds and at 45 seconds.
The boiler pressure, pump pressure extraction time will change from location to location, machine to machine, and from espresso blend to espresso blend. Again - It's all in the cup!

If you find that at 8 bars of pump pressure, 0.9 bar boiler pressure at 30 seconds - the espresso tastes "out of this world" then that is how you need to extract your espresso.
At high altitudes, due to the problem of boiling points, you need more time to extract the espresso. This requires slightly lower pump pressure, slightly lower boiler pressure and longer extraction time. This is achieved easier by using a lighter roast of beans and working with the elements (water, boiler pressure/temperature, pump pressure, grind - and even messing around with the thermosyphon), to create the profile you are looking for.
I make a living making sure that my customer's blend profiles taste the same whether in Denver (5280 ft. elevation), Breckenridge or Aspen (8,000 - 10,000 ft. elevation), and beg to differ with anyone who claims there is no problem extracting espresso in high altitude.

Tal
Espresso Smith Inc.

Far be it from me to suggest that someone should not play around with such things as boiler temp, extraction temp, pump pressure, what have you, in order to extract the best espresso possible. I would do this at sea level, not only at altitude.

I have no experience making espresso above 5850 feet (where I live), and in fact never was into this process when I lived at sea level so my experience is limited to my current altitude where I have lived for more than 12 years and where I've owned (and own) two different commercial espresso machines (Cimbali Juniors, both). From personal experience therefore I can't comment on what you see at 8,000 or 10,000 feet.

What I can say is that at altitudes of around 6,000 feet, I don't think you need to play around with extraction times, pump pressures, or the like, anymore than you would need to do so at sea level.

And this is coming from someone who HAS done almost every imaginable machine mod on my two machines, up to and including pump pressure mods, delay of onset of pump pressure (delay on make timer as detailed in my posts on that which were suggested by Michael Teahan), and dual PID's, not to mention someone who roasts his own beans in a commercial sample roaster.

ken

Taking Tal's advice, I lowered my boiler pressure to .95 - 1.1 range, and I raised the brew pressure to 8.5. While I still need to dink around with my flush-n-go technique, I must say that I've seen a marked improvement in the 3 shots that I've pulled at these new settings. I was able to get one that I'd call good, and that is a FIRST! Now I think it's just a matter of refining my grind and flush-and-go technique, but I'm seeing the light at the end of the tunnel!

Matthew...let us know what you experience with your Scace.

The typical boiler pressure setting in N. America is considerably higher than that found in Italy, due to the proponderance of milk drinks made on this continent. Granted, higher boiler pressure does make frothing go faster, perhaps at some expense in froth "quality."

A boiler setting such as you have now, 0.95 - 1.1 bar, would be, if anything, HIGH in Italy (for a HEX machine), even if it is at the low end of the range for N. America. My PID'd rotary Cimbali Jr. has it's boiler pressure at about 0.8 bar (non-fluctuating), which I use most frequently for straight shots, bumping the boiler pressure up a few degrees if I'm going to do a lot of frothing.

My point is that what you have done would probably give you "better" straight shots with more reproducible extraction temps, AT SEA LEVEL. I don't think that what you have done is working "better" because you live at altitude. This is NOT altitude specific advice even if it might be even more beneficial at altitude.

ken

I've been messing around with flush routines, pstat settings, and intershot temps/times. Here's what I've found as a starting point:

Boiler pressure: 1.3 bar
Pump pressure: ~8.7 bar
Intershot time: ~2 min. 30 sec. (Beginning of extraction to beginning of extraction)

Routine:

1. Beginning with the machine "on" with the PF in the group for at least thirty minutes (mine is on 24 hrs.), flush 6 ounces of water.

2. After two minutes, flush an additional 3 ounces from the group. Watch the clock or preferably start a timer.

3. At 1:15, remove PF. Knock out spent puck if present, wipe, dose, distribute, tamp, and have PF locked back in with the extraction started at 2:00.

This has yielded a brew temp of 199F over and over - as long as I'm following the routine. Want to go hotter? At step #2, flush 2 ounces instead, and increase your intershot time by 15 seconds. Want to go cooler? Do the opposite by flushing more and decreasing your intershot time. Not going to be able to make the next 2:00 extraction mark, but want to pull another shot still? Flush two ounces of water at the 2:00 mark treating the end of that flush the same as the end of an extraction - brew temp will remain stable for the next shot two minutes later (although I have not done a series of sequential flushes with a temp reading later down the line).

I know the boiler pressure is on the higher side. With a lesser setting though, brew temps trend downward at that intershot interval, an interval which I would rather not make longer. If anything, I'd like a stable one that was shorter since I frequently make three to four drinks at a time. Also, you may have noticed that there is no PF wiggle/rinse in the above routine. I could not make one work for me without losing temp stability, at least not at that intershot interval. I tried to incorporate one at different parts of the period in between extractions, but I would always realize a loss of brew temp. I may be asking too much out of my machine.

I would rather have a simpler flush routine such as Dan's "HX Love". That routine is great because the barista has an easily identifiable mark that further flushing and starting of the extraction can be timed from (the end of the water dance). In most cases, the barista is flushing "down" to a certain temp which is below their local boiling point. In my case, if I desire a brew temp of 199-200F, I have to flush several degrees below that temp to reach the end of the water dance. I then have to let the hx water rebound up to the desired temp. Until recently, I had no idea what this rebound time was. Now that I have a thermofilter, I discovered a rebound time. It's longer than I expected. I further discovered that it was not repeatable ... something else I didn't expect. If I attempt a series of extractions, the brew temp trends downward. My current theory for this is that due to the repeated flushing down below the target temperature, the thermal mass of the machine loses stability.

I am going to do more experimenting, but this is the info I have so far. If anyone has any suggestions or notices error in my process, please say so.

Matthew Brinski

Well, I have been trying Matthew's 2 minute flush routine for a couple of weeks now and it has been working well. The only problem I'm experiencing is the second shot does not seem to have as good of results as the first shot. Right now my boiler pressure is set much lower than Matthew's, so I might need to play with that.

My husband has ordered a thermocouple device so in another couple of weeks we should be getting pretty scientific about the espresso!

Matthew...any new discoveries on your end?

Yeah, the more experimenting I do, the more variables I discover (temp variables) ... it can be quite frustrating. In real terms regarding actual taste quality of extractions, the best experiences I've had of late are with Terroir's Northern. I do two three ounce flushes from an idle machine, one ounce flush at 1:30, and pull a shot at 2:30 - sink it (season the PF - it's stripped to brass). I then continue to repeat the [1:30 / 2:30 flush/extraction] routine which has been yielding a somewhat consistent brew temp of 194/193. The Terroir has become one of my favorite coffees for both straight shots and macchiatos with this routine.

Matthew Brinski

Matthew,

I'll give the Terroir a try. Right now I'm working on some Intelligentcia Black Cat and we're really liking it.

We got the thermocouple hooked up. My husband soldered it into a bottomless portafilter so that the probe is approximately mid-puck. With your 6 oz/wait 2 minutes/3 oz./wait 2 min./pull shot, I seem to get fairly consistent results around 198 - 200 degrees. As many have posted, the black cat is very forgiving.

Just for anyone's reference, attached is a chart showing how temperature and pressure in a boiler are related as a function of altitude. Perhaps, yet another reason to PID a heat-exchanger equipped machine for making that transition from point A to point B.



All other factors being equal, high altitudes will reduce cooling flush requirements.

Saturated steam properties were taken from http://www.x-eng.com and data checked at random against Thermodynamic Properties of Steam by Keenan & Keyes. I'll be happy to send the MS excel file (of the chart) to anyone who wants it.

Edited: Added 9000 ft. elevation data since that was the OP's location, added 10000 feet and cleaned up chart a little.

Edited Again - 01/31/2014 - better pic.

Eric S.
erics@erols.com

Okay, I'm missing something basic. How do you have temps above the boiling point of water without ending up with live steam again?

Hi there, you should try to adjust the temperature and pressure of your machine. In high altitudes there is a problem when water boils at 92°C your coffee tends to be bitter. The flavor of your beans also change with different temperatures, so you may need to play again and again with the 4 "M" in a good "espresso".

If you are not sure of how to adjust your machine, contact a service man to do the job.


Regards,



Alex.: