Beezer wrote:Getting a small plastic gicleur and plugging it into the thermosyphon would seem to be a much quicker and cheaper solution, though obviously you lose the adjustability feature.

Jon shows the steps in Installing thermosyphon restrictor on expobar office pulser, but he had the advantage of a properly sized restrictor. Then again, if you had Eric's handy thermocouple adapter, a nylon disk, a bunch of drill bits, and a lot of patience, it sounds doable.


Mysterious white disk is secret to taming the "Expobar Dragon"

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.

And here is a more detailed reply:

I'm really curious about this. On my T1, the group idles at 211 degrees when completely stabilized (running the boiler at .8 - 1.0 b and measuring at the "port"). If I reduced the thermosyphon flow to the point that it idled at, say 204, I would reduce the cooling flush noticeably because the brew water would not leach as much energy from the group mass, correct? How would this lower group temp effectively increase recovery time?

Certainly you would reduce the cooling flush requirements-- I agree with that. As regards recovery time, a better statement on my part would have been that you increase the recovery time relative to the particular machine in question. As the OP has a Quick Mill Anita (as do I), my response was inherently slanted towards that line of machines (Anita, Andreja, Vetrano). Whether or not it is a correct answer for an Elektra T1 is, perhaps, up for grabs, with a tilt towards me being incorrect-- and here's my take on why. Saying this with a slight smile "I don't believe a machine that has a 6 liter boiler and 2000 watt heating element has any problems whatsoever with "recovery" that would be better applied to the human side of the PF as said human is trying to keep up with the Elektra's capabilities before keeling over in a pool of sweat.

The same cannot be said for the Quick Mill machines at their normal(?) pstat settings of 1.10 to 1.25 bar (maximum gage readings) and, if they were set to duplicate your setting of 0.80 to 1.00 bar (min to max), ya better grab a pillow.

When I said "there is no such thing as a free lunch", I meant that you would need to sacrifice some in the ability of the machine to pull rapid consecutive shots. If you have a machine that can do this rather easily with no modifications (Elektra), you sacrifice nothing(?). On the other hand, if the machine is either hard pressed to accomplish this or simply cannot, I believe a thermosyphon flow reduction will penalize that particular aspect of the machine's performance (recovery).

Shouldn't the Hx water heat back up to boiler temp at the same rate as before the mod?

I don't think so because you are inherently inputting less energy into the boiler as would be evidenced by a reduced total "on-time" for the heating element. The amount of energy you need to put into the boiler (steady-state idle) is governed by the heat loss to the environment by the grouphead, the thermosyphon lines, and the boiler itself. The major change the mod makes is in the temperature of the grouphead -- as it was supposed to do. While it surely varies from machine to machine, idle condition hx outlet temperature is about 15-20 degrees less than AVERAGE boiler temperature.

At the end of the shot, wouldn't the group head be relatively close to brew temp, or likely somewhere between high idle and brew temp?

At the end of a shot, Anita's grouphead temperature goes below desired brew temp because, at least momentarily, a reverse thermosyphon action takes place. A lot of this will also depend on the technique used to pull the shot. The size of the hx in Anita is small -- 110 ml.

From what temp profiling I've done, it appears that the group mass itself actually changes relatively little during brew activity, whether it be cooling flush or pulling a shot. Granted this was measured on the outside surface of the group head, not in a well, for instance. But I don't understand why you would need the "recovery" to (in my case) 211, if that's what's implied by your statement.

I kinda believe the Elektra is designed for a more rigorous duty cycle than Anita or her siblings. It would be interesting, of course, to compare Elektra's flushing temperature "curve" to Anita after agreeing to a specific baseline and flushing volume. But that would just be for fun -- I don't think anything could be gleened from the comparison. I also believe Elektra's grouphead has a little more mass than the standard E61 which would buoy your statement as regards temperature changing very little.

I don't believe you "need" the recovery to 211 but if you really wanted to compare apples to apples, you should judge the recovery time back to the original starting point, whether it be 211 or 204. If the Elektra (or any machine for that matter) can demonstrate EQUIVALENT performance under a strenuous duty cycle but at a lower grouphead temperature, then I would reach the conclusion that the Elektra's engineers should have kept the lights on a little longer. Or perhaps there is something that I am missing . . .

I just don't see how there would be any detriment to keeping the group internal temp closer to the target brew range, as long as you didn't reduce the group idle temp to the point that it's below the target brew temp, and any temp above that would really be wasted thermal energy.

Well, I would have to say you are correct for a particular class of machine, e.g. the Vibiemme Domobar has a 2.0 mm restrictor (dealer applied) to the hx outlet and I have seen zero complaints from owners re pulling multiple shots. If you do a search on A.C. for posts by Greg Scace (keyword = thermosyphon), you will also see where he increased the length of his hx outlet line (by a factor of 3) and succeeded in reducing the group temperature of his Astra from the low 200s to 198.

I have to believe that someone has played with these configurations before.

Do the search on A.C. as I suggested and you will gleen a lot of info. What parameter(s) are you using to judge the completion of your cooling flush?