Time from cold until ready to brew - Page 3

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Ken Fox

#21: Post by Ken Fox »

another_jim wrote:You and the others are optimistic. These machines aren't at their best until they are in thermal equilibrium with their surroundings, around 1 hour after warm up. This is true even of the little Silvia, as Eric said.

On the other hand, 20 amp appliance timers aren't all that clunky -- especially after your sense of coffee appliance scale has been adjusted to the levels we tolerate around here :D
I would extend that time considerably for commercial level machines. If you doubt me, run random walk up Scace shot tests over a period of MANY hours, and you will probably find that even 4 hours is not enough, if your goal is a true steady state condition. Don't just run these tests one time, run them over a number of warm up cycles and see how the results pan out.

I do not consider my machines to have really reached equilibrium until at least 8 hours have passed, e.g. overnight. This is based on years of testing, not just a few series done to try to convince myself I'm on to something :mrgreen: When I read posts from people using machines having 2 or 5 liter boilers who think they can use their machine (stably) after an hour or so of warm up, my reaction is that these people are fooling themselves if they think that they are really obtaining consistent shot temperatures.

Before people jump in and say that this is only true of Cimbalis, and that E61s or other designs don't have this issue, run some REAL Scace thermometry and then get back to us. I'm not talking about 1 or 2 Scace shots, I'm talking about a real series, say at least 8 or 10 or more shots, separated by variable time intervals. Run these Scace series over a number of warm up cycles to be sure that you are getting truly representative data as I have found that one shot series over one warm up cycle can be misleading.

This does not mean that (maybe) you couldn't arrive at some sort of quasi-equilibrium earlier, however I am very unimpressed with any data other than random shot temperature curves obtained with a repeatable test system such as a Scace and a datalogger, because this comes as close as possible to mimicking real usage patterns for a commercial machine used in a home setting. Grouphead temperature or flush data is perhaps correlated but in fact does not verify the desired actual result, e.g. the shot temps themselves.

As I have stated in earlier posts, I do not believe that tight temperature control is the be all and end all of espresso shot production, however it does have some importance. The larger is the machine the more time it is going to take to reach true temperature stability, and my opinion is that many people running large machines off of a timer do not leave their machines on long enough to become truly temperature stable.

What, me worry?

Alfred E. Neuman, 1955