How does high altitude affect brewing?

Beginner and pro baristas share tips and tricks.
mtnwoman

#1: Post by mtnwoman »

I am having a VERY difficult time getting anything even close to drinkable from my new Vetrano/Macap stepless. I danced with water to exhaustion last night, pulling 10 shots and throwing them all out. All were very bitter.

I'm starting to wonder if the fact that we live at 8800 ft. altitude is affecting something. Water here boils at 92-94 degrees f. Do I need to modify the water dance for this? It seems that when I do the 6 oz. (which is also equal to stop sputtering plus 6 seconds) I have completely drained the hx. In other words, right around 6 oz. the water reduces to a slight dribble.

I also seem to have to grind finer than the rule-of-thumb that has been recommended. Whereas Chris said to start at about 2.5 numbers from the burrs touching, I'm at about 2 numbers right now.

So, I'm chasing the grind and temperature around. And around. And around.

Any ideas out there?

bruce

#2: Post by bruce »

I cannot offer any suggestions, but I recently had a very good espresso at a cafe in Mammoth Lakes, CA (7800 ft). If someone is pulling a decent shot in a production environment, you can surely do it at home. Wish I had the name of the place- you might try calling the visitors bureau. It was not the Looney Bean, but in their old location.
By the way, I think you meant to say water boils at 92-94 Celsius, not Fahrenheit.

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HB
Admin

#3: Post by HB »

I also have no experience with preparing espresso at higher elevations, but The Denver Effect offers suggestions, especially "use coffees that brew well at lower temperatures."
mtnwoman wrote:Do I need to modify the water dance for this? It seems that when I do the 6 oz. (which is also equal to stop sputtering plus 6 seconds) I have completely drained the hx. In other words, right around 6 oz. the water reduces to a slight dribble.
Not sure what you mean by "drained the HX"... there is no draining it:

Image
From How I Stopped Worrying and Learned to Love HXs

The dribbling you observed is probably the flow after the HX is exhausted of over-temperature water (video). Given that the end of the water dance and your target brew temperature are so close, I would expect the flush-n-go technique would work better than the rebound method described in the HX Love article, or a shorter flush and shorter rebound (e.g., two seconds past end of dance, 20 second rebound).
Dan Kehn

mtnwoman

#4: Post by mtnwoman »

I'm starting to wonder if the fact that we live at 8800 ft. altitude is affecting something. Water here boils at 92-94 degrees f.
OOPS, I meant to say that water boils at 192-194 degrees f.

I do plan on visiting an espresso bar in a neighboring town that is 7500 ft. elevation and picking their brains. I think I'll also try the flush-and-go or a shorter water dance method. My husband the engineer is convinced that anything that is liquid that is coming out of the machine is close to 194 degrees, because anything over that would be steam.

Does anyone have any suggestions for blends that perform well at lower temps?

I REALLY appreciate all of the help that I have received from this forum. Dan, you're a jewel!

Ken Fox

#5: Post by Ken Fox »

I don't think that Schomer knows beans about high altitude espressomaking and would not give credence to the article that Dan quotes ("Denver Effect"). Denver isn't even that high. There are those of us who don't think that Schomer makes a good espresso at SEA LEVEL, at least if you are talking about his blends. But then that is entirely a matter of personal taste.

I live at 5850 feet and have no problem with this issue; water boils at around 201F where I live. I'm sure there is an altitude where it becomes difficult, perhaps impossible, to pull good shots, but I'd guess that altitude is more like 10,000 then the altitude of Denver.

Espresso is made under pressure in a sealed container (the PF). Granted, the PF opens at the bottom but by then the temperature of the exiting beverage is unlikely to be above your boiling point. There is an issue of "flashing," whereby you have to deal with the fact that the boiler temperature is in fact much higher then your local boiling point, especially in a HEX machine. You should play around with various flushing regimens to see what works best for you. Dan's recommended water dance technique may not be best at your altitude. Experiment and you shall find what works best.

And of course do experiment with blends and roast levels and temps and all that sort of stuff you should play with in the first place. There is no substitute for learning basic barista skills. There is no reason that I can think of why altitude should effect grind settings, so something else such as distribution, packing, the coffee, the other obvious stuff, are the most likely culprits.

Good luck.

ken
What, me worry?

Alfred E. Neuman, 1955

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Psyd

#6: Post by Psyd »

You might try and contact the folk at this shop, as they kinda made their mark adjusting machines to operate at altitude. In the interest of full disclosure, I don't work for them, I don't know them, and I have no vested interest in their shop. I would take a t-shirt if they offered, though.
Espresso Sniper
One Shot, One Kill

LMWDP #175

mteahan

#7: Post by mteahan »

The temperature in the boiler is regulated by the expansion of steam vapor in a closed vessel and measured against a spring in the pressure stat, not outside atmospheric pressure.

Therefore, you could be on the moon and the temperature would be the same at the head, figuratively speaking.

Boiling water in an open vessel is different, and so long as the water temp is boiler the altitude based boiling point, the extraction temperature is unaffected.

Michael
Michael Teahan
analogue | coffee

mtnwoman

#8: Post by mtnwoman »

...so long as the water temp is boiler the altitude based boiling point, the extraction temperature is unaffected.
Michael,

Could you elaborate on this?

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HB
Admin

#9: Post by HB »

If I may introject, Michael is referring to how the boiler pressure is unaffected by the atmospheric pressure; if the boiler pressure gauge reads 1.1 bar, the boiler temperature is 255F whether the machine is located on Death Valley or Mount Everest. The diagram below from How I Stopped Worrying and Learned to Love HXs shows the whole system:

Image
Thermosyphon circuit and heat exchanger (solenoids / valves omitted)

At higher elevations, water exiting the group to atmospheric pressure will flash boil at a lower temperature (you report it's 192-194 degrees F at your locale). I suggested a flush-n-go approach because the difference between the boiling point and your desired brew temperature is so small. In contrast, there's +10F degrees difference where I live, so the time between the end of flash boiling and reaching the target brew temperature during a cooling flush is relatively long, allowing me a greater "margin of error." To put it another way, I would have the same narrow timing issues if I loved my espresso brewed at 210F.
Ken Fox wrote:Espresso is made under pressure in a sealed container (the PF). Granted, the PF opens at the bottom but by then the temperature of the exiting beverage is unlikely to be above your boiling point. There is an issue of "flashing," whereby you have to deal with the fact that the boiler temperature is in fact much higher then your local boiling point, especially in a HEX machine.
The issue of timing the cooling flush aside for a moment, does the atmospheric pressure really matter once the group repressurizes, as Ken suggests? Say for example you wished to brew at 202F. Obviously the water will flash boil as you do the cooling flush, but once you lock in the portafilter and pressurize the group, the local atmospheric pressure doesn't matter (again assuming the temperature of the espresso exiting the portafilter drops below the boiling point).

Not sure how the initial shock of steam prior to repressurization will mess with the extraction though... :shock:
Dan Kehn

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another_jim
Team HB

#10: Post by another_jim »

At 8800 feet, your boiling point is 91C or 195F;
http://www.fetco.com/boilingpoint.htm
which does put you in a slightly dicey situation in regards to espresso making. In general, there is roughly an 5C or 9F drop in brew temperature from the top to the bottom of the puck, so you might be able to brew at any desired temperature. However, you have two potential issues:

1. The temperature at the bottom of the puck, where the espresso is exiting rises throughout the pull and will get closer to your brewing temperature, as measured at the top of the puck. Towards the end of the pull, you could get flash boiling of the exiting espresso and destroy the crema. You will need to adjust the brew temperature to prevent this.

2. If you desire to brew at higher than the local boiling point, which is very likely for yours, then, as Dan said, you'll still get boiling water when you flush the group before a shot. This means you won't have an optical indication of how much to flush. How much of an issue this is will depend on the machine you are using -- in a double machine, it's not much of an issue, although the flash boiling may require a longer head-heating flush. On an HX machine with a cold group, you may also need a longer than normal flush to heat the head. On thermosyphon groups like the E61, you may want to consider a way of monitoring temperatures. Doing this very accurately is expensive; but for this purpose, cheap will do just fine - an inexpensive thermocouple up the spout of the PF will tell you what you need to know. The cheapest TC I know of is part of a the Chinese multimeter sold here:
http://www.store.yahoo.com/techbuys2003/tm-125.html
Jim Schulman