I edited the name of this post for clarification...

I recently bought Dragonfly's Dolce. I was looking for a starting point for extraction and found one or two people saying that since they are extracting this in CO and are a mile above sea level, I might need to increase the brewing temperature that they recommend to compensate for the difference in altitude. For example of they are extracting at 198, i might find a similar extraction at 201 or something like that. Dragonfly is in Boulder CO, about a mile above sea level. Water boils at around 203F there. I am in MD very close to sea level where water boils at 212.

Initially, this makes sense to me. However, after a little more thought, it does not and I want someone to tell me if I am missing something.

Boiling is a phase change - liquid to gas. Altitude effects the phase change by reducing atmospheric pressure. Less pressure makes it easier for the water to change to gas phase - it boils at a lower temperature.

Altitude does not change the amount of energy in the water at any given temperature. 201 water in Boulder has the same energy as 201 water in MD. Right?

Water boils at 203 in Boulder, since 201 is below the boiling point in both Boulder and MD, 201 water should have the same effect on extraction in both locations. Right?

I do think I would need to make some sort of accommodation for difference in altitude if we were talking about the optimum sea-level extraction temperature being HIGHER than the boiling point of water in Boulder. For instance, Josuma's Malabar Gold has a recommended extraction temperature of 204. Again water in Boulder boils at 203 and so I would have a problem extracting at 204 because my water would be phase changing - boiling - and not behaving like a fluid.

Thanks for your help.

I'm at 4400' here in Salt Lake City, a bit lower than over the hill in Colorado. The only variable I've changed for the coffees I buy (roasted mostly @ sea level) is that I need to let them rest a few days longer than the roasters recommend. I don't know if the beans just offgas CO2 more due to reduce air pressure or not. If I don't give them at least a week or more, they pull gassy & inconsistent.

I drink espresso regularly at an on-mountain cafe @ Alta ski resort @9500' & they don't do anything special. I think they're running Unic commercial HX machines, pulling shots @ around 200 F

lancealot wrote:it boils at a lower temperature.

Right.

lancealot wrote: 201 water in Boulder has the same energy as 201 water in MD. Right?

Right.

lancealot wrote:201 water should have the same effect on extraction in both locations. Right?

Right.

lancealot wrote:and found one or two people saying that since they are extracting this in CO and are a mile above sea level, I might need to increase the brewing temperature

I think the predominant advice works the other way - that you may need to brew at a lower temperature AND use a roast that prefers that lower temperature. (Chris Tacy's post here is one early example.) Newer advice tends to advise not fooling with the brew temp. Of course, if you are talking about boiler pressure, you would need a slightly higher gauge pressure to achieve the same absolute pressure and temperature as an equivalent sea-level machine.

lancealot wrote:I do think I would need to make some sort of accommodation for difference in altitude if we were talking about the optimum sea-level extraction temperature being HIGHER than the boiling point of water in Boulder.

Yes, this is primarily at higher altitudes where the optimum brew temp is higher than the local boilng point and the brew may exit the PF a little over-bubbly. But still, people often choose to keep the recommended temp and ignore the bubbles ( Espresso at altitude - Could use some theory . Note also in that topic that allowing a longer rest after beans are roasted is something that is often recommended by people and shops making espresso at altitude, and may be the primary way of dealing with David Schomer's oft-cited failure to brew espresso in Denver over 20 years ago ( https://espressovivace.com/archives/lucidcafe/LC15.pdf )

Also, if you have an HX and use the "water dance" to time your cooling flush, your timing will be different at altitude. Modern HX machines with thermosyphon restrictors that favor a cool group may show no flash boiling in a flush at sea level, but a clearly noticeable one at 5000 ft.

Thanks for the reply burrero.

homeburrero wrote:
I think the predominant advice works the other way - that you may need to brew at a lower temperature AND use a roast that prefers that lower temperature. (Chris Tacy's post here is one early example.) Newer advice tends to advise not fooling with the brew temp. Of course, if you are talking about boiler pressure, you would need a slightly higher gauge pressure to achieve the same absolute pressure and temperature as an equivalent sea-level machine.

I think you and I are on the same page and you just read me wrong / i communicated poorly.

To make sure. You are trying to say, that the predominant advise is... if you are extracting at altitude, "you may need to brew at a lower temp AND use a roast that prefers a lower temperature."

lancealot wrote:To make sure. You are trying to say, that the predominant advise is... if you are extracting at altitude, "you may need to brew at a lower temp AND use a roast that prefers a lower temperature."

Yes, that's what I see as what was the predominant advice. The newer advice does seem to be that your ideal temp at altitude will probably be the same as it was at sea level, but at altitude you probably want to allow the beans more rest post-roast.

This is great advice here. I'll be moving from sea level to about a mile high in NM at the end of Feb.

I had another thought about this. If water enters the brewing chamber and pressure quickly begins to build, that pressure in the chamber will alter the boiling point of the water. The difference in the boiling point will be altered significantly and the boiling point will be much higher. I got curious about it and searched on here to substantiate this theory. I found a thread (linked below) where a poster wrote that the boiling point at 9 bar is 365 F. This can easily be fact checked but I don't see the point.

I don't have direct experience but physics tells us that as-far-as temperature goes, extracting espresso in Denver and Baltimore is the same thing.

High Altitude Brewing

I can confirm as someone who was recently living in CO ~5,000' and then moving to TX ~30ft, the altitude makes a pretty big difference for shots. So much so that I stopped making espresso after a while and just stuck to V60 because I found the water not getting hot enough in my machine to get the extraction I like. Most shots were too bright for my palate, and it didn't really help that I had a huge stash of fruity Kenyan and Ethiopian beans for home roasting. My advice would be to roast a little darker with a longer development time if you have lower water temps and maybe grind a bit finer than you would at sea level where higher temps would make the shot run quicker. My $0.02.

Another funny CO story is that I once fried a water kettle at the office after I turned it on and left my desk for a sec, only to be gone about an hr due to being pulled into an impromptu meeting. The temp sensor never shut the heating element off because it never registered a boiling temperature so it kept on "boiling" at low 200s until there was no water left and eventually the element blew out. It was one of those mini travel kettles that holds about half a liter.

Somewhat tangential question: is 1.0 bar in a sealed system actually going to be a lower temp at altitude? I asked Reiss from Londinium about this when setting up my Londinium R (I'm in Boulder), and he said since the boiler is sealed, altitude wouldn't matter.

It makes sense that the water would boil more quickly the first time it is boiled, thus achieving 1bar of pressure in the boiler at lower temps. But from that point forward the boiler never draws air in from the outside, just water. So, wouldn't it end up achieving 1bar at the same temp regardless of altitude? Or, am I missing something?