Flow control + Lelit MaraX

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#1: Post by Tjyven »

I am interested to see what you who use flow control think about it. I have a MaraX myself so I am most interested to see what those people who also have that machine think about that combination. Am of course interested to see what others also think even though other machines have different stock flow rate. The MaraX only have about 5ml/s as stock flow rate which is lower than most other machines.

How high flow rates do you get using the flow control? Heard some people saying you should not have higher flows than the stock flow, do you agree?
What roasts/beans do you get best results with?
What kind of profiles do think is the best?
Other thoughts? Problems?

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#2: Post by another_jim »

The Mara X has a tighter restrictor and softer preinfusion spring than a stock E61. If you use a needle valve, also get a stiffer spring, otherwise the flow rate will be quite low. The flow rate, if you crank a flow control with a stiff spring all the way up, will be far higher than a stock E61. It's not a good idea unless you are looking to go retro, and do 1990s darkish roast, coarse grind, overstuffed basket, vintage Seattle Linea shots.
Jim Schulman

Tjyven (original poster)

#3: Post by Tjyven (original poster) »

Aha, I thought the preinfusion spring only affected the pressure for about the ten first seconds but changing to a stiffer spring will give a higher flow during the whole shot? I tried the flow control from coffee-sensor for a very short while without changing the preinfusion spring and then I got flow rates of max 7,5-8 ml/s. Guess the stock 5 ml/s is actually a flow suited for good medium roasts.

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#4: Post by Nunas »

This is a tough call, since the Mara X is an HX machine, albeit a modified one, there's only room for one device on the e61 group head. The choice is usually a brewing thermometer (such as EricS) or a pressure gauge (such as those supplied with FC kits). Generally, on an HX, I would rather have a thermometer; but my experience was with a Magister, which is a dragon-HX. On a DB, the thermometer is much less important, so I'd opt for a pressure gauge (with or without FC); which is what I did with my Synchronika. But, the Mara-X has a reputation for being more temperature stable, possibly making a temperature gauge a bit less important. The bottom line is, IMHO, up to the owner. Only you can decide on which of the two gauges would be the more important to you.

Tjyven (original poster)

#5: Post by Tjyven (original poster) » replying to Nunas »

Agree with that, both are interesting but non of them seems essential. Think I would normally have the pressure gauge and sometimes change to the thermometer just to see that the temperature is as it should.


#6: Post by BoulderGeek »

I have a basic Lelit Mara PL62ST, with non-adjustable PID. So, for me, the thermometer is pretty useless without a method to adjust temperature points.

I installed the Bianca flow control kit. I can't say that it made much difference to my flavors. I have tried longer preinfustions, slower shots, restricting to 6 Bar, etc. Ultimately, I get good shots, and my machine looks cool. My shots don't taste $230 better to me, no matter what I do.


#7: Post by leeherman99 »

I just posted my experience with Lelit flow control on the Mara X on the main Mara X stream (Lelit MaraX, post 609). Briefly, the flow response is highly non-linear. It may be useful to just tune the flow more finely - I haven't determined that yet.

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#8: Post by Jeff »

Non-linear is likely as the flow through an orifice is, I believe, proportional to its area and the square root of the pressure difference across it. Though not a circular, unrestricted orifice, I'd expect a similar relationship. There isn't a "2 mL/s" setting of the valve except at one pressure differential. There's roughly 9 bar across it as the basket fills, dropping to perhaps 1 bar during extraction - probably close to a 3x difference in flow.

As long as you don't expect it to be "calibrated", a flow-modulation valve can help limit basket-fill rate and modulate pressure/flow during extraction.


#9: Post by leeherman99 »

Jeff - the MaraX already has a kind of automatic preinfusion, I'm guessing caused by compression of the very soft spring in the lower part of the grouphead. There's no way to modulate the pressure/flow during extraction in the stock machine, except for the old-fashioned way (grind size and amount of coffee in the filter basket). My problem, in my short experience, is that trying to reliably adjust the flow using the flow controller lever is really, really difficult. The smallest deviation causes a huge jump in the pressure.

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#10: Post by another_jim »

When they added flow control, Lelit replaced the the stock E61 preinfusion spring with a stiffer one. The very soft spring in the Mara X is going to exacerbate the problem. Have you made the replacement?

FWIW, I think you are going against the Mara's "don't fiddle with the pressure or temperature, just make your d*mn shot" philosophy. But the fairly precise temperature controlled group head makes it an attractive target for adding a pressure mod.
Jim Schulman