I would be very grateful if some one from the community can help me achieve a specific behavior -
I'm trying to replicate a pre-infusion behavior/profile of 3 bars 6-7sec and then 9 bars until shot ends
My rocket machine behave as follow - when i open the lever fully - it slowly ramps up to 3-4bars and then up to 9 bars constantly until i put the lever down.
first drop usually comes in 7-8sec, shots are great and have no complains, i just think i might get better shots with the behavior i described or by limiting the pressure to 3 bars steady for example as long as i want before going to 9bars.
I saw videos and researched about this topic and i understood that my machine is vibe pump and not rotary pump so it behaves like that.
I understood that i can use the "pre-wetting" option when the lever is almost open but the pump is not active (i see drops of water), but i would love to be able to replicate the behavior i described.

does flow control device will allow me achieving that exact behavior of machine running straight to 3bars (6 or maybe more seconds) and after going up to 9 bar constantly?
can i use different device or mod? i really like tech stuff and I'm into taking my espresso to next level with my current machine.

note: when i pull lever with zero basket i get slow ramp to 4 and then up to 9 bars and my machine holds there.
Thanks in advance

Rose, The issue with your machine (or any HX) is one of monitoring. By far, the most useful accessory for an HX (I'd call it essential) is a group head thermometer, such as the EricS. Alas, with one of these fitted, you cannot read the group head pressure on most machines, since the pump pressure is taken before the jet (gicleur). So, on most HX machines (maybe yours), you can monitor either group head pressure or temperature, but not both. There are threads here on H-B, where some folks have been trying to find a way around this limitation. As far as I'm aware, none of the proposed solutions give accurate brew water temperature, since they take the temperature reading on the e61 "nose", not from deep in the brewing water path.

BTW, when you see a gradual rise to about 4-bar then a subsequent rise to 9-bar, what you're seeing is the inbuilt preinfusion of the e61 group. At about 4-bar, it automatically switches from preinfusion to brew.

Now, with that out of the way, let's assume that you fit a flow control device, including a manometer, to the e61 instead of a temperature gauge. This could work if you know your machine's group head temperature response very well. Let's also assume that you switch out the preinfusion spring of the e61 to the stronger spring supplied with the FCD kit. This essentially removes the aforementioned inbuilt e61 preinfusion. The flow is now entirely dependent upon how far one opens the FCD valve, bearing in mind that the developed pressure is largely affected by coffee being in the portafilter. That is, with no coffee in the PF, or no PF installed, there will be little to no pressure, while with a blind basket installed, the pressure will eventually rise to the pump pressure.

So, to get your desired profile with this set-up, you would start the machine with the FCD off or nearly off. You would then ride the control knob to achieve the desired pressure profile. Note, however, that the pressure will attempt to change constantly, first rising as air is ejected from the coffee, then as water causes the grinds to swell, and then, throughout the extraction, it will attempt to drop as coffee solids and oils leach from the puck. The control isn't a set and forget thing at any particular pressure, but it is easy to "ride" the control and keep whatever pressure you desire, with a bit of practice.

I hope this answers your question
- Maurice

Hey Maurice, i appreciate your long informative answer.

regarding the thermometer, i understood that my temp can change (although i understood that the pid i have in the machine should keep the temp right).
example i put it 119, as rocket chart says it's 92.7C.
i'll get one, i also have the pressure gauge built in, so i can see them both at same time.
i understood that the thermometer might show 2-3c less since it's a bit far from the head group.

regarding the flow control - i have a pressure gauge built in the machine, so can i put the thermometer instead of the kit pressure gauge? i guess yes?
and "enjoy" having them both?
so as i understood the pressure will change because of the parameters you mentioned. but i can "lead" it to where i want?
for example if i want the the behavior i mentioned 3 bars for 6sec if i see the pressure goes up or down i should react and keep it where i want?
Some members mentioned that after having the kit they couldn't keep constant pressure, my default setup holds 9bars you might see a needle drop like around 8.6-8.8.
BTW - what's the point of measuring the gr/ml water coming out after installing the valve? is it water + pressure i want to know? to be more correct in my "copying" other machine's behavior? as i understood the water coming out will control the pressure happening so why measuring the water coming out.

another question - if i use the pre wet technique i see that the coffee comes out faster like 6-7sec,
if i just push the lever-pump on with out the "pre-wetting" technique, i might see 10-11 sec before coffee comes out.
what would be the ideal method and time to drop or
maybe i shouldn't use the pre-wet and grind coarser?
as i understood too much delay in the head cause over extraction to happen?

Thanks a lot!, i really appreciate your answer, as i came here after no one could really help me
Love the information, rose

theboyinthesky wrote:<snip>i understood that my temp can change (although i understood that the pid i have in the machine should keep the temp right)...example i put it 119, as rocket chart says it's 92.7C...i understood that the thermometer might show 2-3c less since it's a bit far from the head group.

This is a common misconception, IMHO. The PID on an HX machine is only marginally better at keeping the boiler stable than is a pressurestat. But, especially on an HX, brew temperature is not a direct function of boiler temperature. It's way more complex than that. On a Dual Boiler machine, it is more relevant, where the 2-3 degrees drop is probably about right. Most HX machines need to be flushed prior to pulling a shot. This is because the water in the HX loop inside the service boiler is super heated. After the flush, you're good for the shot, but then the HX needs a bit of time to recover; this varies greatly between machines. Some newer HX machines have reengineered the thermosyphon loop so that the temperature is lower at the group and less prone to shooting out steam when first pulling the shot. However, as far as I know, HX machines all require at least some flushing. My old Magister required a lot of flushing, as the Stella is one of the old school "dragon" HX machines. Even my current DB machine benefits from a little flushing. This is why I opine that a thermometer is essential on an HX machine, at least until one has used it for a considerable time. Once you become one with the machine, as it were, it isn't quite so important. That said, I always used the thermometer on my Magister.

i also have the pressure gauge built in, so i can see them both at same time....regarding the flow control - i have a pressure gauge built in the machine, so can i put the thermometer instead of the kit pressure gauge? i guess yes? and "enjoy" having them both?

I don't know your machine, but on most HX e61 machines, and on my DB e61, the gauge on the machine reads the pump pressure, not the pressure at the portafilter. Frankly, the pump pressure gauge is of marginal use. Of course, you can spot when a pump is dying, or use it to adjust the pressure valve or bypass, as the case may be. So, unless your particular machine reads group pressure, you'll have to choose between having a thermometer or a manometer.

so as i understood the pressure will change because of the parameters you mentioned. but i can "lead" it to where i want?
for example if i want the the behavior i mentioned 3 bars for 6sec if i see the pressure goes up or down i should react and keep it where i want?
Some members mentioned that after having the kit they couldn't keep constant pressure, my default setup holds 9bars you might see a needle drop like around 8.6-8.8.

Yes, you can maintain or change to whatever pressure you like, up to the pump pressure, assuming a dense enough puck of coffee. It takes a bit of practice, as there's a bit of lag time between moving the control and the pressure change.

BTW - what's the point of measuring the gr/ml water coming out after installing the valve? is it water + pressure i want to know? to be more correct in my "copying" other machine's behavior? as i understood the water coming out will control the pressure happening so why measuring the water coming out.

There isn't much point of measuring water debit, beyond knowing that your control is operating properly. Water debit has very little to do with what goes on in the portafilter. One thing it does do is allow you to know when your FCD is adjusted to the same size aperture as your original jet. When I installed my FCDs, I first measured the water debit with the original mushroom, then did a water debit table using the FCD. In the case of my machine, about 1.25 turns open is the same as the original in the Synchronika.

another question - if i use the pre wet technique i see that the coffee comes out faster like 6-7sec, if i just push the lever-pump on with out the "pre-wetting" technique, i might see 10-11 sec before coffee comes out. what would be the ideal method and time to drop or maybe i shouldn't use the pre-wet and grind coarser? as i understood too much delay in the head cause over extraction to happen?

I don't know This all depends on how you want your coffee to taste. Before I had a FCD on my DB, and also when I had my HX (no FCD), I experimented a lot with pre-wetting. Typically, with the HX, I would raise the lever for about five seconds, then move it to the middle position and wait for a few drops of coffee to come out, then I'd re-raise the lever to engage the pump. I sometimes do this with the Synchronika, but most of the time, I use my FCD to achieve something similar. Frankly, I'm not sure if there's any such thing as over extraction. I like my coffee really rich-tasting and so I grind finer than usual and use a very long preinfusion.

Nunas wrote:This is a common misconception, IMHO. The PID on an HX machine is only marginally better at keeping the boiler stable than is a pressurestat. But, especially on an HX, brew temperature is not a direct function of boiler temperature. It's way more complex than that. On a Dual Boiler machine, it is more relevant, where the 2-3 degrees drop is probably about right. Most HX machines need to be flushed prior to pulling a shot. This is because the water in the HX loop inside the service boiler is super heated. After the flush, you're good for the shot, but then the HX needs a bit of time to recover; this varies greatly between machines. Some newer HX machines have reengineered the thermosyphon loop so that the temperature is lower at the group and less prone to shooting out steam when first pulling the shot. However, as far as I know, HX machines all require at least some flushing. My old Magister required a lot of flushing, as the Stella is one of the old school "dragon" HX machines. Even my current DB machine benefits from a little flushing. This is why I opine that a thermometer is essential on an HX machine, at least until one has used it for a considerable time. Once you become one with the machine, as it were, it isn't quite so important. That said, I always used the thermometer on my Magister.

First thanks for you help and time.
When i just got the machine i immediately adjusted the pid to 119 (as rocket says it's 93.7). it was set to 120-120 (around 95-96).
then i was confused as the manual said to wait for the boiler to reach 1(green zone). and actually it can't reach there as 119 is just a bit lower.
so when i play with the pid i do see the boiler temp change accordingly.

So the PID to your saying has the affect of changing the temp to my desire but i will require flushing as the group head overheat or has lower temp desired immediately after a shot?
(Another example, i had a package of dark roast they sent me, and the taste was really harsh until i changed the pid to 117, but maybe there was another factor, i'm just a beginner asking/sharing info).
Anyway in 2 days i'll have the group head thermometer and i will reply here some of the details. I'm very curious to see what's going on
BTW so what temp should i see at the thermometer? a bit lower than actual brew temp?

Nunas wrote:I don't know your machine, but on most HX e61 machines, and on my DB e61, the gauge on the machine reads the pump pressure, not the pressure at the portafilter. Frankly, the pump pressure gauge is of marginal use. Of course, you can spot when a pump is dying, or use it to adjust the pressure valve or bypass, as the case may be. So, unless your particular machine reads group pressure, you'll have to choose between having a thermometer or a manometer.

As a beginner it helps me, when i do coarser grind i can see the pressure doesn't go over 5-6, sometimes i see a bit lower than 9 (maybe i tampered in lower force or lost 1gr somewhere in the preparation?
Anyway i can't use both to your saying, so the pump pressure is not identical to the pressure on at the portafilter, is it showing in a delay or?
because as it seems it does correlate to what's going on with my coffee pack

Nunas wrote:Yes, you can maintain or change to whatever pressure you like, up to the pump pressure, assuming a dense enough puck of coffee. It takes a bit of practice, as there's a bit of lag time between moving the control and the pressure change.

I understand, in case i have hard time with it, can i easily go back to default behavior? of the automated pressure. or i need to remove the kit completely?

Nunas wrote:There isn't much point of measuring water debit, beyond knowing that your control is operating properly. Water debit has very little to do with what goes on in the portafilter. One thing it does do is allow you to know when your FCD is adjusted to the same size aperture as your original jet. When I installed my FCDs, I first measured the water debit with the original mushroom, then did a water debit table using the FCD. In the case of my machine, about 1.25 turns open is the same as the original in the Synchronika.

so measuring the water before and after is just to see that the water that comes out isn't greater(ml) than before?
and when you say "1.25 turns open" is the same as original, it means you won't go further open with the valve?
just to know your action range? thanks!

Nunas wrote:I don't know This all depends on how you want your coffee to taste. Before I had a FCD on my DB, and also when I had my HX (no FCD), I experimented a lot with pre-wetting. Typically, with the HX, I would raise the lever for about five seconds, then move it to the middle position and wait for a few drops of coffee to come out, then I'd re-raise the lever to engage the pump. I sometimes do this with the Synchronika, but most of the time, I use my FCD to achieve something similar. Frankly, I'm not sure if there's any such thing as over extraction. I like my coffee really rich-tasting and so I grind finer than usual and use a very long preinfusion.

I saw in many places that if water spends "too much" time with the coffee you can get over extraction.
i have a friend that works as barista that advised me to see first drop in 7sec. it's incorrect? or incorrect if you do pre-fusion or pre-wetting.


Thank you very much

theboyinthesky wrote:<snip>Anyway in 2 days i'll have the group head thermometer and i will reply here some of the details. I'm very curious to see what's going on BTW so what temp should i see at the thermometer? a bit lower than actual brew temp?

Bearing in mind I don't know your particular machine, my advice is for generic HX machines. Maybe someone with your version will jump in here with some machine-specific advice...they usually do. Anyway, on an HX machine, one generally sets the service boiler temperature/pressure desired for steam. To get the brew temperature to the proper point, one flushes the machine just past the point where steam no longer comes out of the group head. When you get your thermometer installed, flush it until you see the temperature you desire. When pulling the shot, watch to see if it stays stable, rises or drops. Then adjust your flush to get what you want. That used to be called flush-and-go...possibly still is. Another technique is to over flush and wait for the temperature to recover to the desired brew temperature (flush-and-wait).

As a beginner it helps me, when i do coarser grind i can see the pressure doesn't go over 5-6, sometimes i see a bit lower than 9 (maybe i tampered in lower force or lost 1gr somewhere in the preparation? Anyway i can't use both to your saying, so the pump pressure is not identical to the pressure on at the portafilter, is it showing in a delay or? because as it seems it does correlate to what's going on with my coffee pack.

Again, as I don't know your machine, I can't give specific advice. I'm surprised that your pump pressure gauge varies. Perhaps I've forgotten how my Magister worked, but on my machine, it does not. In any case, I think it is doubtful that whatever pressure is displayed is the actual brew pressure.

I understand, in case i have hard time with it, can i easily go back to default behavior? of the automated pressure. or i need to remove the kit completely?

No, you never need to go back to the stock mushroom. To get the "normal" flow, you just adjust it to the position established when you do your water debit test that equals the stock mushroom flow, as I described earlier. If you also want to restore the e61's inbuilt preinfusion, then you merely need to switch the spring back to the one that came with your machine. Actually, at the risk of adding some confusion, some of us, myself included, have gone back to using the e61 spring with our FCD, instead of the one that came with the kit. This gives variable e61 preinfusion time at the onset. Then, when the pressure rises above ~4-bar, the control operates exactly as it would with the FCD spring.

so measuring the water before and after is just to see that the water that comes out isn't greater(ml) than before?
and when you say "1.25 turns open" is the same as original, it means you won't go further open with the valve?
just to know your action range? thanks!

I'm not sure if I understand the question. What I suggest is that you measure how much water comes out of your group head in a given time without a portafilter. Then, after installing the FCD, repeat the measurement at 1/4, 1/2, 3/4...turn. From this, you'll know exactly where the FCD setting is the same as a stock mushroom. This has nothing to do with where you operate the FCD, other than if you want to set it to "stock".

As for where to set the control, it will turn about two turns from fully closed to fully open. However, most of us have opined that in most use, there's no reason to go beyond about a turn and a half, or even less. In my case, even though my stock mushroom gave the same water debit as my FCD at 1.25 turns, most of the time I operate it from zero to about 3/4 turn.

I saw in many places that if water spends "too much" time with the coffee you can get over extraction. i have a friend that works as barista that advised me to see first drop in 7sec. it's incorrect? or incorrect if you do pre-fusion or pre-wetting.

There's no such thing with coffee as "correct" in my opinion. What you want to do is experiment with all sorts of variations, changing only one variable at a time until you get to know the machine very well and discover what tastes best to you. This takes me to a few recommendations concerning HX machines.

I suggest that you first get used to the machine without FCD but with thermometer, at least until you're comfortable with the flushing process. After you can reliably flush based on experience and not by watching the thermometer all the time, then take the thermometer off and put the manometer and FCD on along with its spring. Then, play with the FCD a lot. Then, put the stock e61 spring back in and experience that to decide which spring you like the better.

Hey thanks again for your answer.

let me please summary the most important questions i have after reading your messages -

1. i still don't get the pid thing, as described by rocket and shown in this photo comes in the manual -

https://www.google.com/url?sa=i&url=htt ... AdAAAAABAD

they do says it has correlation or setting the brew head temp, it is a lie? or I'm missing something.

and i understood the flush and go or flush and wait, but let's say i seek for 92.5C, which temp should i expect to see in the group thermometer?(less/above.. or).

2. which flow control would you recommend? do they all operate they same? (they look to have the same components.)
preferable the ECM branded one?

Thank you very much,
highly appreciate your information sharing.
Thanks

Hi again Rose,
Regarding your questions, as I said, I don't know your machine at all. As far as I know, it's a standard HX machine. I don't know if it's an old school "dragon" (like the Magister Stella) or a newer one with a flow restrictor in the HX circuit (like the MaraX). In either case, my guess is that the manufacturer of your machine knows that most buyers won't get a group head thermometer. So, they've produced that table as a way for the average user to make some sort of reasonable espresso. Anyone who ends up on these pages, on the other hand, is usually chasing the god-shot, not just acceptable espresso. Unless some other members who have your machine chime in here, I stand by my suggestion that on an HX machine there's no substitute for a group head thermometer, and that its principal use is to achieve the optimum brew water temperature by flushing the group. Perhaps if you read this article, you'll understand why https://knowyourgrinder.com/how-does-an ... ne-work-2/. As you can see, the boiler water in an HX machine is not used to make espresso. It only makes steam and hot water. The brew water picks up heat by passing through a tube inside the boiler (that's the heat exchanger). So, while it is possible in an HX machine to lower the boiler temperature/pressure to achieve a given brew water temperature, this can only happen at the expense of producing less steam. If you're only drinking shots, then this might be a reasonable approach. But most folks buy an HX machine to be able to make milk-based drinks.

Regarding your second question, I have only the ECM (Profitec) FCD and the Coffee Sensor kit. There may be a few others. The two I have are nearly identical in quality and function. The ECM kit that I got cannot easily be taken apart to replace its internal O-rings (I don't know about the current version). The Coffee Tech one can be taken apart, and it comes with replacement O-rings. The manometer on the ECM kit is a black on white background and a bit bigger. The manometer on the CS kit is available in either black on white or white on black.
Cheers - Maurice