Help with water flow adjustment with Lelit (Bianca) FCD and paddle

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Vindibona1

#1: Post by Vindibona1 »

I'm confused and perhaps misunderstood the Lelit Flow Control Device (with Bianca paddle) that I had Chris' Coffee install on my Quick Mill QM67.

When the QM67 arrived everything was installed except for the paddle which was packed separately for me to install. Based on the way that YouTube videos presented the Bianca and flow control I was under the assumption that there was only 180° of travel in the valve. I didn't check before installing the paddle for the first time. Consequently I initially set it up with the valve closed and put the paddle fully turned to the left. Obviously there was no water flow when in that position. I ASSUMED THAT FULL RIGHT WOULD ALLOW FULL, UNRESTRICTED water flow from the machine. My assumtions were totally wrong and the valve can rotate 1.5 revolutions from closed to full open. Consequently the amount of flow adjustment is limited with the paddle, unlike the two other popular FCD's, one with the ball from Whole Latte Love and the other from Quick Mill- though the main differences appear to be the knobs/paddle that attach to the valve spindle on the Lelit FCD.

I did some water flow measurement tests,without portafilter to see how much water flow was with the range of the Lelit(Bianca) paddle and was a bit surprised. Here's how it shook out.

*With spindle adjusted full clockwised (valve closed) paddle positioned far left the "slowest" water flow was 0g/sec. With the paddle positioned to the far right the max flow with was 4.5g/sec.

*With spindle adjusted full counter-clockwise (valve full open) the paddle to the far left gave 5g/sec and fully open was 7.8g/sec (nominally 8g/sec).

*Right now, the spindle adjusted 90° off of fully closed (1/2 of paddle range from left to right) then paddle mounted full left, the flow from full left (toward closed position) is 4.5g/sec and full right opening up I geg 6.6g/sec, which is about 200g/30 seconds.


So I presume, as shown by the second setting I can get nominally 8g/sec of flow with the FCD positioned to fully open the valve. I got the Lelit FCD largely because it had a simplicity of the paddle only turning 180°, again presuming it would represent the valve fully closed to fully open.

And so I think there is one or two possible choices. 1) Find the optimal range for the paddle in regard to the valve and water flow grams/sec. 2) Possibly locating a knob for the spindle that would allow the full 1.5 rotations of the spindle/valve.

Me knowing nothing about how much water flow and setting with or without paddle is optimal (or sub-optimal). With the paddle to the right, how much water flow do I need? I would presume max flow might be a priority over the minimum flow with the paddle to the far left. What do the exerts here suggest?

Edit: Below find a photo taken with blind disk installed, measuring pressure with paddle to the full left and full right. Left paddle position was taken first, the right-most position taken second with no change to the pressure. As (paddle set on spindle) Min flow= 4.5g/sec, Max flow=6.6g/sec. I'm not sure what any of this means in a practical sense? Please advise.


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bringyoutomyhell

#2: Post by bringyoutomyhell »

A stock Bianca will have 6/7 ml/s of water debit when the paddle is fully open on the right, when all the way to the left it's not always zero but close to. But in your case it seems that the difference is even less between fully open and close

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Jeff
Team HB

#3: Post by Jeff »

Understanding a bit of the physics may help to start. It's not a flow-metering valve, but an adjustable restriction. The flow through that restriction is related to the pressure difference across it. You've demonstrated that at zero flow, there's zero pressure drop, as long as the valve is slightly open. You can note the position of the knob that gives, say, 4 mL/s without a basket and call that "4 mL/s", but it is really more "4 mL/s when there is 10 bar across the valve". As soon as you have back-pressure from the puck, the flow will drop.

As for what do you "need"?

For the profiling I and many others do with light roasts, there are periods of basket-fill in the 5-10 mL/s range, zero-flow stages, and extraction at 4-8 bar in the basket with delivered flow rates in the 3-8 mL/s range. To get 3-8 mL/s delivered at pressure, the setting will need to be higher than the no-basket position for that flow. Based on that it sounds like you need to select a new knob that gives you greater range.

Vindibona1 (original poster)

#4: Post by Vindibona1 (original poster) » replying to Jeff »

You're probably right about the different knob. I'll have to call on Monday. This flow rate thing is new to me. I just came off of a Gaggia Classic. If I didn't have the FCD installed would I have gotten the 7.8ml/sec rate if it just had the mushroom, or even more?

So to recap, you think I need more range in the waterflow? I with I had known that when selecting the FCD. I could have purchased the Quickmill one for $48 cheaper.

Edit: I actually found a knob from one of my electric guitars that I installed momentarily on the restrictor valve spindle. The rotation is a bit stiff so needs a lever on it, but in the meantime if I had to use one of those I could. But I've sent an email in the meantime. The part that I find irritating is that the Lelit (or Lucca) FCD sells for about $300 while the Quick Mill one sells for $225 (all before discounts) If the difference were just in the paddle/knob then it may have made no sense to pay up for the Lelit, though that paddle is pretty and the other knobs are quite pedestrian.

It would seem that at the moment the currennt range 4.5g/sec- 6.6g/sec seems to be the most desirable range, I think as I can do pre-infusion by starting with the paddle full right, lifting the brew lever to the pre-infusion position, then starting the actual brew cycle, dialing it abck to 4.5g/sec toward the end of the pull. The last shot I made was done that way. The La Colombe published "recipe" is 16g in -32g out 22 seconds, which I converted to 18g:36g/25 seconds. I did make the grind a bit finer to accommodate the pull-back but was right at 25 seconds at the end, not including pre-infusion. This is really hard to be good at. Milk frothing was a little better today, still a bit of a mess and far from the consistency of doing latte art :0.

Vindibona1 (original poster)

#5: Post by Vindibona1 (original poster) »

bringyoutomyhell wrote:A stock Bianca will have 6/7 ml/s of water debit when the paddle is fully open on the right, when all the way to the left it's not always zero but close to. But in your case it seems that the difference is even less between fully open and close
Being a weekend I was sort of stuck doing my own testing (not a bad thing). I'd watched some videos and wanted to see if there were recommended minimium and maxium water debits on both ends. Knowing that I can't get the paddle to swing more than 180° I thought, at this point, to see if I could find an acceptable range for now. Below is the method of what I came up with for the range until I can figure this all out.

I figure I could pre-infuse with a 3mL/sec bath and could probably live with a 6.4mL/sec full flow rate. I'll have to test for pressure with this setup tomorrow, but it might work. What I discovered is that the 540° rotation of the needle valve isn't linear. If I set the paddle off 90° from closed, and can limit to 3mL/sec and a 180° paddle turn will yield 6.4mL/sec... but the full 540° open needle valve will only give my 7.8mL/se, then the last 270° only gives another 1.2 mL/sec flow. I could be seriously wrong and can blame my medications. But I double checked the flow rates I've listed at the bottom.

In looking at reviews of the Quick Mill FCD and the one they sell at Whole Latte Love which seem to have the same degree of rotation, I suppose with the ball knob and the tall small lever, it would be good to have full range of the flow. So I have to wonder if those systems are more linear to take advantage of the extra 270° tha you don't get with the Lelit paddle? Just thinking this through. And I suppose if 6.4mL/sec is enough to provide sufficient pressure resistance against the puck, then I suppose having only a 180° range of motion isn't so much of a limitation. Is my thinking off or on?

Below is the protocol I used for positioning the paddle this afternoon. Do you think I got my flow at least in the ballpark? Obviously the paddle won't let me adjust from full open to full closed like the ECM and Quick Mill knobs do.

Resetting:
1) Close valve (gently)
2) Move to ½ position for 3g/sec
3) Reposition paddle to far left.
4) Check flow @ full paddle right (open)
5) Next test- check pressure @min and max with ground coffee puck in portafilter.


Currently Adjusted 6/26/2022 as noted above

Full paddle Left 90mL/30sec= 3mL/sec
Full paddle right 192mL/30sec= 6.4mL/sec

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bringyoutomyhell

#6: Post by bringyoutomyhell »

You can ask Lelit about the two limits of the range. Profitec/ECM flow control can turn a lot (more than 360° actually) but it's cumbersome. It's true that the Lelit paddle doesn't give the full range, but you don't really need it, it was designed that way and it's a highly regarded machine. I would not change the paddle (also be wary when you close completely the flow, you can damage the gicleur if you press too much towards the zero). I would just choose your preferred range, but I would check with Lelit/your vendors to be sure that your valve is ok. There were cases of a broken something inside which always gave too much flow. I would search inside this thread Lelit Bianca User Experience

PIXIllate
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#7: Post by PIXIllate »

After much experience with a flow control my opinion is you need a range of <0.5ml/sec - 7.5ml/sec.

Maybe take the wooden handle off and notch it out so it clears the machine?

Vindibona1 (original poster)

#8: Post by Vindibona1 (original poster) »

bringyoutomyhell wrote:You can ask Lelit about the two limits of the range. Profitec/ECM flow control can turn a lot (more than 360° actually) but it's cumbersome. It's true that the Lelit paddle doesn't give the full range, but you don't really need it, it was designed that way and it's a highly regarded machine. I would not change the paddle (also be wary when you close completely the flow, you can damage the gicleur if you press too much towards the zero). I would just choose your preferred range, but I would check with Lelit/your vendors to be sure that your valve is ok. There were cases of a broken something inside which always gave too much flow. I would search inside this thread Lelit Bianca User Experience
I was home sick all weekend so we had a chunk of time to do some testing and experimentation. With the paddle there is a range limitation and I sought to find which one might work the best. One article that I read was by whole latte love which gave a primer on profiling. In the article they put up a chart that indicated how much flow with occur within fractions of the full rotation of the ball control. The one that I downloaded was for the vibratory pump. And so I translated their positions in terms of milliliters per second into what I thought was a good range with the paddle, notating the few recipes that they provided.

I haven't done a pressure check with any of that yet, but this morning I plan on doing an experiment with their "sweet bump " profile, all charted out. With the paddle settings I have, I've tested a max flow rate of 6.4 mL per second. With roughly a reserve rotation of 270° there is only a reserve of 2.2 mL per second debit. I could reset the battle is needed to accommodate that 7.8 mL per seconds max. But that would leave the minimum in the range at 4.5 mL per second, which I don't believe is acceptable. Perhaps I mistaken, but that's my current assumption.

I do have an immediate solution for testing purposes. The knobs from one of my guitars is the right size to fit securely on the shift of the FCD. Spindle is a bit stiff so that kind of knob isn't ideal but would work in a pinch. But for now I'll work with the Lilt paddle and my calculated flow range. I suspect that it would be better to have a slightly lower water flow debit than to blast the grinds with too much water too quickly. But I'm so new to this "deep dive" anything I'm thinking at this moment could be upside down. There was only so much that I could do with my Gaggia classic. I have never thought of brewing coffee as a "hobby" before... but here I am.

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bringyoutomyhell

#9: Post by bringyoutomyhell »

I encourage you to do some real testing with coffee, but I'm sure you'll never need more than 6ml/s,, that's the upper range of the needed flow, it's better being able to go lower when closed IMO

PIXIllate
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#10: Post by PIXIllate » replying to bringyoutomyhell »

It can be very useful to start a shot with a very high flow rate to quickly introduce a lot of water and saturate the puck as quickly as possible to avoid a top to bottom extraction gradient. One of the most often emulated shots is a lever and some of those machines can start with a massive inrush of water on the order of 20-30ml in the first second or so. The fact that the Londinium profile is one of the most often used on a Decent machine would attest to this.