Hi everyone,

I spoiled myself with a new machine - ECM Synchronika with Flow Control. I really like it snd just starting getting used to it. My machine in not plumed so I thought the the Flow Control would come in handy, to allow preinfusion. Something is weird though, I measured what was the flow rate with the mushroom (no flow control device) and checked what should be the FC position to be at the same rate (NOT fully opened). The FC device seems to do what it supposed to by limiting the flow of water to the group. However, when brewing, the behavior is strange. From the YouTube video I saw, it seems like the position of the flow control directly correlates to the group pressure. What I'm witnessing is that when pre infusing (FC allow very small flow) the pressure jumps from 0 to a very high pressure close to first drop of coffee. If I leave the FC in the same position it starts dropping afterwards. Also it seems like there very little wiggle range, meaning the pressure gauge shows max pressure after the FC is being slightly more opened, but very far from the point where the flow of water matches the water flow without the FC device.
I would love if someone have some thoughts or experience with this combo.

LG75 wrote:However, when brewing, the behavior is strange. From the YouTube video I saw, it seems like the position of the flow control directly correlates to the group pressure.

This is not how the e61 FC devices work. They produce something equivalent to acceleration from a gas pedal in a car (borrowing from JakeG describing difference between e61 FC and the FC on his GS/3, where the paddle position is directly tied to a brew pressure, can't find the thread at this moment). What you're describing after that is expected behavior. You have to tighten the needle valve to reduce flow during preinfusion, I usually end up closing mine all the way for a few seconds or longer (light roasts). The pressure drop you're seeing is the deterioration of the puck, which reduces its resistance (your manometer at the group is measuring resistance produced by the puck as some amount of water flows into it).

Your observations of the extreme acceleration of pressure, even with small amounts of flow, seem a bit strange. Have you measured what your flow output is at different turn amounts?

Unscrew the bottom part of the group and check to see that the preinfusion spring is there. Also, do you know if your machine came with the stock preinfusion spring or the much firmer one that is now included with most FC kits? The sudden rise in pressure is not normal, except when the FC valve is wide open and the stock spring is in place. I have not tried to see what would happen with no spring, but I hypothesize that you might get a sudden jump even at low FC control settings. FYI, the stock preinfusion spring is set to about 4-bar, while the FC kit spring is much stronger, probably over 9 bar.

With the stock mushroom the flow was ~218.5 grams of water in 20 seconds. The Mushroom is a hexagon, so if we say it takes six steps to make a full circle then getting that 218.5 grams in 20 seconds takes a bit less than 8 steps
One step - 30.5 gr
Two steps - 70.7 gr
Three steps 87.5 gr
Four steps 121.5 gr
Five step 147.1 gr
Six Steps 169.4 gr
Seven Steps 189.6 gr
Eight steps 224 gr
These numbers are, of course, with water free running from the group head

Nunas wrote:Unscrew the bottom part of the group and check to see that the preinfusion spring is there. Also, do you know if your machine came with the stock preinfusion spring or the much firmer one that is now included with most FC kits? The sudden rise in pressure is not normal, except when the FC valve is wide open and the stock spring is in place. I have not tried to see what would happen with no spring, but I hypothesize that you might get a sudden jump even at low FC control settings. FYI, the stock preinfusion spring is set to about 4-bar, while the FC kit spring is much stronger, probably over 9 bar.

I installed the FC device and replaced the spring with a harder one. Screwing it back was the most challenging thing in the installation, as you need to push up and screw. That wasn't that hard, but I know that the spring is there

Well, so much for that idea Do you have any water debit (flow with no coffee) when the FC is set to totally shut?

LG75 wrote:Hi everyone,

I spoiled myself with a new machine - ECM Synchronika with Flow Control. I really like it snd just starting getting used to it. My machine in not plumed so I thought the the Flow Control would come in handy, to allow preinfusion. Something is weird though, I measured what was the flow rate with the mushroom (no flow control device) and checked what should be the FC position to be at the same rate (NOT fully opened). The FC device seems to do what it supposed to by limiting the flow of water to the group. However, when brewing, the behavior is strange. From the YouTube video I saw, it seems like the position of the flow control directly correlates to the group pressure. What I'm witnessing is that when pre infusing (FC allow very small flow) the pressure jumps from 0 to a very high pressure close to first drop of coffee. If I leave the FC in the same position it starts dropping afterwards. Also it seems like there very little wiggle range, meaning the pressure gauge shows max pressure after the FC is being slightly more opened, but very far from the point where the flow of water matches the water flow without the FC device.
I would love if someone have some thoughts or experience with this combo.

I think the pressure changes you discuss are due to how the coffee puck behaves over time during the process of extraction. As you probably know the puck behaves like a variable resistance outlet filter to water flow in the brew chamber. How it behaves will depend on the fineness and size distribution in the grind, the amount of coffee in the basket, and the degree of tamping pressure that was applied to it. If you prepare the coffee so that it extracts "normally" from the unmodified e61 group head, it should extract very close to the way it does when you brew it in an e61 with the flow control set to the standard water debit (around 9.5ml/s with vibe pump or around 11ml/s plumbed with rotary pump). You can compare the two extractions by watching the brew pressure gauge during extraction without flow control and with it. Remember to keep everything else the same.

You may need to adjust your grind, dose, and tamp, as inconsistencies in these will certainly affect the pressure profile during extraction.