How does high altitude affect brewing?

[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]

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.

[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."

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:


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).

[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]

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

[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.

[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

[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?

[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:


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.

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...

[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

[HB]

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.

I wondered if Eric's thermocouple adaptor would be helpful, even if you used a type K sheathed TC and a cheap multimeter. OK, it's probably a little overkill...

[mteahan]

All the speculation about boiling temperatures at altitude and the effect on extraction is missing the point. The water temperature of the boiler is not affected at all by altitude.

Nada, Zero, Zip.

Can I be more clear than that?

The only argument that could be made is that the water leaving the group at a temperature above the boiling point at altitude would vaporise the water upon contact with the outside air. However, once the pressure in the portafilter chamber hits 0.5 bar, even that argument goes away as the pressure would compel any water that WANTED to transform itself into a gas would be prevented from doing so.

If the operation of the boiler in heating water was somehow determined by the boiling point of water, then altitude could make a difference, but it doesn't.

"This is not the droid you are looking for"

[HB]

All the speculation about boiling temperatures at altitude and the effect on extraction is missing the point. The water temperature of the boiler is not affected at all by altitude... Can I be more clear than that?

Sorry, did I miss something? While you, Jim, Ken, and I haven't said it the same way, I believe we are all in complete agreement.

[mteahan]

You might be right. I suspect the conversation has moved to the water temp as it exits the group, which I addressed in the second part of the post.

The espresso leaving the portafilter will not be at a temperature above the boiling point of water at altitude.

[bruce]

Wouldn't the dissolved solids in the espresso raise its boiling point above that of pure water?

[Matthew Brinski]

I have been really biting my tongue on replying to this thread. I also have a Vetrano and a Macap just as you. Furthermore, I live at 8,500 feet. I will tell you that you can get really decent shots at this elevation, in my opinion. I have had a few cups that left me saying "Damn, that was REALLY good!" Having said that, I have also had a lot of bad shots. The reason I have been reluctant to reply is that I don't know if I have found the best routine for brewing at this altitude, and I want to relay a somewhat quantified and systematic approach to you.

My current practice consists of:

1. I flush the group while listening to it without the PF (I usually flush while simultaneously distributing and tamping), and cut the pump just as the audible
boiling/hissing fades out. I have learned through practicing some group flushes that the "hissing" returns at 25 - 30 seconds after the group flush which
I presume is the onset of boiling water at the local boiling point (approximately 196 - 197F). To avoid brewing with boiling water, I start my extraction
at 25 seconds after the stop point of the group flush so that I am brewing with as high of a temp water that is possible without boiling.

2. I pull a restricted double (mine are usually 1.25 to 1.5 oz) in a range of 24 - 28 seconds. I pull a double ristretto based on the learned theory (thanks to
Jim Schulman on your awesome article) that the bitters will balance out the initial acids/sours that are more prominent in a low temp extraction - at
least, this is the way I have understood and experienced it thus far.

3. If I experience trouble with acidity with certain blends, I'll sometimes cut the initial 1 - 3 seconds of the shot (let it go into the drip tray). I really don't
like to depend on that approach though. I feel as if I'm robbing the potential of the shot as a whole.

I have been trying to experiment some with letting the HX rebound longer than my normal interval to increase extraction temp. The problem with this is that I have no idea what temp I'm extracting at.

It's been mentioned by some (people who have coffee knowledge many levels above mine) that local boiling temp is not a concern due to the brew water being under pressure. I totally understand the concept. My issue with this though is that when I let my hx rebound longer, the shots can taste burnt or bitter. Is this due to the initial infusion that is boiling water (you can hear it during the initial extraction)? Is this due to the rebound being too long with the temp getting too high? I don't know. Furthermore, I have had more hit and miss shot consistency with channeling while extracting with the brew temp being above boiling. I think that the initial "gassing" infusion of brew water compromises the integrity of the prepared puck. Maybe there's something I can do to correct this through my technique - I don't know.

Speaking of technique, if you don't have a bottomless pf, I would encourage you to get one. I prefer spouted pf's, but my bottomless was INVALUABLE in self training my dosing, distribution, and tamping. If those aspects of your technique aren't consistent, neither will the taste of your extractions, regardless of a stable and proper brew temp.

Anyway, I have been sticking to my 25 second routine lately due to the amount of guessing that goes into other approaches. I have a Scace on order, and I will do A LOT of experimenting when I get it. Hopefully, I'll be able to relay a flush/temp control routine after I get some hard data that correlates to good extractions. My data logger is going to be busy.

Matthew Brinski

[mtnwoman]

Matthew,

I'm glad you stopped biting your tongue!! I'm excited to find someone else who has the same set-up as I do. At the very least we need to share notes...either in this forum of via email! I'd love to know how you have your grinder set, what beans you are experimenting with, etc.

It sounds like you are doing some version of "flush-and-go" as Dan has recommended. I plan on trying this with my next shots.

I did get my bottomless portafilter yesterday and pulled one hurried shot this morning. I think my tamping is spot-on, but I still need to fiddle with the dosing to get the timing of the shot closer to 25 seconds.

I really appreciate all of the good advice this newbie is getting from the seasoned folks!

[Espresso Smith]

"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.

[hbuchtel]

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

Great, you are in good company!

Henry

[Matthew Brinski]

Tal,

I'm glad you jumped in on this. I REALLY want to experiment with pump pressures and extraction times/volumes (and I have already to a certain degree), but I'm waiting for a Scace device to arrive so I can correlate brew temperature to the other variables. I want to know the specifics of what works not only to make repeatable extractions, but also to make an attempt of actually understanding the hows and whys of what works well. One thing that you mentioned that I have found to be true through experience is the use of a lower pump pressure. I am currently having best success with 8.5 bar. I am also having greater success with pulling restricted shots. I have had good shots up to 40 seconds (triple basket at 1.5 ounces), but lately have been sticking around 28 seconds (using both ridged and ridgeless double baskets at 1.25 - 1.5 ounces).

Something that I'm curious about is whether or not the actual extraction process at the coffee grind itself behaves differently at high altitudes. I would guess not, but I have no idea.

Matthew Brinski

PS - Can you recommend any places in Breck that pull decent shots? I have experienced nominal at best in just about every town in this state, with exception to a couple shops in Denver and Boulder.