Espresso machine issues - false pressure

False pressure

Sometimes when you turn on an espresso machine it heats up, but not to the temperature it is supposed to get to.  On a heat exchanger, for example, the steam boiler (the only boiler) may heat up to far below the desired temperature for functionality.  There is an easy solution to the problem in the short term.  You start the machine heating up.  It seemingly comes up to temperature and then you purge the steam wand letting off the false pressure and then it will finish coming up to temperature.  This is a reasonable solution, but not a perfect solution.  The problem is that you have more active management than you might like.  

Now there are potential helpful trick that I recently blogged about, which is that you can put your machine on a timer.  This is not as good a solution if you have false pressure as if you do not because the machine will start preheating, but stall out when the false pressure kicks in instead of allowing you to walk up and pull a shot first thing.  There are still all the problems of timers though.

It is in some sense an improvement though since it reminds me a bit of the annoying way Microsoft is set up on my work computer.  You start the machine and then  many minutes later the machine is ready for a password and then many more minutes later it is ready to use.  If you could enter the password at the start or end it would be much more efficient.  At least with the time you don’t have to actively take part twice, but only once.

Now unlike the Microsoft problem the bright side is that there is usually a solution for false pressure.  You can take off the vacuum breaker and descale it and this will often solve the problem.

Here is a helpful description of false pressure from Bill Crossland, the main designer behind the GS/3

“Everything expands when heated. Gases expand faster than solids. In the case of a steam boiler with air and water; when heated the gas (the air) expands much faster than the solid (the water). The pressure in the boiler increases quickly due to the expanding air. The expanding air causes the pressure switch to activate, turning off the heating element. Once the air is released and is replaced by water vapor then everything returns to normal.”

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