In some recent threads on the "Buying Advice" forum, I've alluded to the brewing temperature stability that you can achieve using siphon brewers:

Itch to buy more brew gear

Help me choose a syphon brewer

Here's an example of what I am talking about:



Out of habit, I always use our Thermapen to measure water temperature in the siphon globe before adding the funnel, and I take another temperature reading in the funnel before adding ground coffee. Over the course of the brewing cycle, I take additional slurry temperature readings before drawdown, just to make sure I know what is going with the brew.

After months of siphon brewing, I really don't need to do this all the time. But it feels like I'm flying blind if I don't. Plus, the data is educational, and can be put to good use. Over time, you develop a feel for what the water or slurry temperature is going to be at different times in the brewing process, and can account for changes in the weather or your routine. To the extent that you can anticipate or predict what the slurry temperature will be after you add coffee, you can target brewing temperatures within a pretty tight range. Most importantly, you can maintain those temperatures throughout the entire brewing cycle.

In this case above, I took temperature readings throughout the brewing cycle. I added the coffee after the water temperature in the funnel stabilized at 199°. Adding the mass of the coffee to the water caused the slurry temperature to drop slightly to 197°. (Often, the temperature only drops by a degree.) Even though I had rolled the burner heat down for the brewing stage, the heat applied to the system caused the temperature to rebound to 198°, where it stabilized. When I turned the burner off to initiate draw down at 2:15, the slurry temperature was still holding steady at 198°.

When you consider the impact of brewing temperature in the cup, it's really nice to be able to control such a critical variable so precisely and predictably. While siphon brewing is nominally more work that other brewing methods, if you have the extra time for setup and cleanup it can also make your life a lot easier, especially if you are nerding out on brewing temperature and its taste impacts.

[You can read more about the figure above, which was inspired by some figures in Scott Rao's book "Everything but Espresso," here: http://bit.ly/1j1KwXP]

I really like siphons for this reason. Sometimes I get frustrated with the amount of variance in temperature in my kettle from beginning of pour to end of pour. And if I'm pouring on more than one dripper, having more water in the kettle is gonna give me a slower rate of change. A lot more variables in slow pour.

Kind of reminds me of the argument between HX machines and double boilers: humped temperature curve vs stable temperature curve. Is one necessarily better than the other? Am I reading too much into it?

Is one necessarily better than the other?

It may only depend on the degree of your obsessive-compulsive disorder.

While "different" does not always equal "better," here's what it says about water temperature in the "The Coffee Brewing Handbook" published by the SCAA:

Cold water doesn't extract coffee as completely or as rapidly as hot water. Water that ranges in temperature from 195°F to 295°F liberates the aromatic materials more rapidly and permits proper extraction of other solubles within a reasonable time. As a general rule, the temperature should remain constant throughout the brewing cycle.

The declining temperature profile associated with many brewing methods likely does produce some desirable effects in the cup. However, these attributes seem inherently more difficult to isolate and control-more subject to kettle volume or environmental factors beyond the barista's control-as compared to using a stable brewing temperature. Ted Lingle, the Handbook author, also notes that:

Second to grind, temperature has the greatest influence on the brew's taste attributes.

Since you can control temperature and time so easily with a siphon, the process of changing a single important variable, like grind size, and isolating the taste impacts in the cup is relatively simple. I know it's not easier to brew a siphon pot than make a pour over, but it definitely is easier for me to find out and control what's going on with the system when I'm siphon brewing.