The manufacturers and distributors of our machines are really in a quandary. What sort of service will the machine see? Will it be asked to pull three shots in three hours or three shots in three minutes? Is the machine going to (and staying in) Denver, Colorado or New Orleans, Louisiana? What is the relative "power" of the thermosyphon system in the machine as designed?

I believe it is worthwhile to install a thermosyphon restrictor of some sorts in a few E-61 hx machines (Izzo, ECM Giotto, & Expobar come quickly to mind) but not necessarily in Anita (or Andreja or Vetrano). I mention the Izzo because I have measured one and found it to run ~ 5 degrees above the Quick Mill machines for equivalent pstat settings. I mention Giotto because it and the Vibiemme Domobar are essentially identical internally. The adjustable thermosyphon restrictor installed in the Faema Legend certainly APPEARS to be a good solution-- a reasonable compromise between the added cost and complexity of automatic control and the simplicity of mandatory user intervention to fit various operating modes. The orifice size that Jon used in his Expobar is 2.5 mm, Expobar P/N 50020020; I believe the orifice sizes available for the Vibiemme are 2.0 & 3.0 mm, with the 2.0 being typically installed; the orifice sizes available for "standard" E61 groupheads are also 2.0 and 3.0 mm but they appear to be installed at the group end vice the Vibiemme installation at the hx outlet end. I can think of no reason (from a performance standpoint) as to why it would make any difference as to where they are installed. For a pictorial of these, go here:

http://www.nuovaricambi.it/index.html

Click on English, Coffee Machines, Faema, then Scheme 11.

For someone wanting to experiment with various sizes, the style of the Expobar thermosyphon restriction orifice is, by far, the easiest to replicate. The OD of the teflon disk is 0.718" and the thickness is 0.078". A way to do this would be to buy 3/4" teflon rod, turn it down to the dimension in a lathe and drill it (in the lathe) to whatever dimension you wanted and then slice the disks like bread. Total cost would be about $15, would take about 30 minutes, BUT of course, that requires a lathe. Applying a variable restriction (a la Faema Legend) to Anita would be tough because of space constraints - not impossible but . . .

Keep in mind that restricting the thermosyphon flow will inherently increase the recovery time for the machine but this may be JUST PERFECT for some users. Personally, I have (and I know it sounds crazy) become accustomed to the cooling flush and I would not judge this to be a worthwhile adventure for the Quick Mill machines. At the same time, that is not to say this adventure has been scratched off my list. There is plenty to learn about these machines and I am having a good time.

Greetings Brad -

By recovery time, I mean the amount of time that would elapse until the machine can successfully DUPLICATE the previous shot. Does this mean that you have to get back to 211? Well, ideally, yes. In reality, the climb back to 211 is asymptotic and if you initiated a flush at, say, 209, you would be flushing less for the second shot. I have never operated a T1 but I would think it could substantially (and understandably) outperform the Quick Mill machines.

The easiest answer to the thrust of your comments would be - there is no such thing as a free lunch. The size of the hx in the Quick Mill machines is, I BELIEVE, 110 ml. After pulling a shot, the AVERAGE temperature of the water in the hx is substantially below group temperature and I notice a reverse thermosyphon action taking place for a short while until the water then in the hx climbs above group temperature.

If one could adjust the thermosyphon flow such that the group idled at a specific temperature, say 198 F (as measured via a thermocouple adaptor or digital thermometer) and the AVERAGE temperature of the water in the hx somewhat higher, say 210 F, it would simply be a matter of pulling the shot with NO COOLING FLUSH whatsoever. If there were no downside to this, machine dealers would be working OT and then some to fill the orders.

The same scenerio applies to simply reducing the pstat to relatively low levels - say 0.70 Bar (max reading) and thus producing a grouphead temp of around 198 F (with the Quick Mill machines at sea level). You can then pull a shot with NO COOLING FLUSH whatsoever but steaming would be marginal and the machine would be limited to around one double shot every 15 minutes (as best I can recall).

The only time the brew water TAKES energy FROM the group mass is when that group mass is at a higher median temperature than that of the incoming brew water. This would be the case when using the flush-n-go technique of shot-pulling.

This may not respond fully to your comments - still thinking about that.