The General ACS Minima Thread

Adrianmsmith · 25 May

It may be easier to find the starting point with open system (no puck) and move the paddle to where you have a mental note of where that point is .

As with @Cuprajake and the bianca my experience with the flow control was on ecm valve and on synchronika. Whilst the principal and function are the same the feel and positioning will be slightly different.

Example , with the ecm variant it was possible ( and widely done!) to fit the paddle at the bottom of the shaft with the valve not closed . it eas then not possible to actually achieve “no flow” as the valve couldn’t be closed past that point . Very simple user error causing many complaints. Another example of noy the manufacturers fault and , in that case, “read the flippin manual”. Haven’t seen the acs flow control leaflet.

Its better to learn the machine first with the flow control in a position where you get the same pump delivery as if it were not fitted. Only then start to use it!!

And yes, the pressure you see is a product of what the pump can deliver AND the resistance or permeability of the puck . The blank filter has its use but not what you were trying to do in learning the feel of the valve . For that you need a dialled in puck.

Fwiw, in a while it will all click in to place and then you will be another one wondering ,“why dont they get it”. 😎🤭🙈🤪

☕☕

Cuprajake · 25 May

Well the bianca you only have 180 degree of movement from open to closed

When i had the coffee sensor flow kit on my minima you had nearly 1.5 turns 🤷

Adrianmsmith · 25 May

Cuprajake Well the bianca you only have 180 degree of movement from open to closed

When i had the coffee sensor flow kit on my minima you had nearly 1.5 turns 🤷

Yey, similarly the ecm valve had just over 2.5 turns

BUT

It Caused some frustration to users because

1 and ¼ turns from closed gave stock flow.

After 1 ¼ turns the pump wasn’t in a happy place and gave variable results so the Rule was use it between closed and 1 ¼ turns only .

@gregE im not saying this is the case with the ACS , just following the theme that they all have their quirks.

May be if interest ….. https://www.wholelattelove.com/blogs/support-articles/4417016413459

https://www.wholelattelove.com/blogs/support-articles/4414963184659

Note both articles are specific to ecm. Included to help you understand what its all about!!

GgregE · 25 May

Thanks both for your comments. I have a good comfortability with the machine and am pulling awesome shots with the flow control in an open position (as if it were not fitted). Now I’m trying to get the flow control down. Good to know that you also experienced variable turns on flow control kits. The stock ACS kit has about 1 and ¾ turns for me.

I know I must play around with it more to get comfortable but my aching question is at start I am aiming for the flow control to allow a trickle of flow around 2 bar. For me on the paddle that’s a little past ¾ turn open. Once I see the pressure reach 2 bar I find that I have to quickly push the paddle all the way back to the left to fully close it to cut off pressure so it stays at 2 bar for a few seconds. I was expecting to only have to move it slightly back to the left just before the ¾ turn where flow starts (because that’s where my starting point is) but it wasn’t stopping pressure when I only went back to that starting point. I had to go all the way back to fully closed/shut. I’m just having a hard time understanding why that’s the case. Does that make sense?

Adrianmsmith · 25 May

gregE

The pump is delivering 9.5 bars of pressure.

You are attempting to control pressure by reducing flow between the valve and the puck.

Its a concept that interests people but you have to understand the flow control valve is just a valve . It doesnt control what the pump is delivering.

Control of flow and control of pressure require different control parameters.

The valve only controls flow and you attempt to control pressure via the permeability of the puck and restriction given by the valve masking the pressure in the system. Its not an ideal situation but with practice you can do what you need, sort of.

On the other hand, without a flow control valve, the acs will produce great espresso with less hassle and frustration.

When i had the synchronika i read a lot about the flow control valve. I have had a lot of dealings in the past priming high pressure pumps in much larger systems than an espresso machine. The more i read the more questions i had and wondered how much practical use a flow control valve could be when what i actually wanted to do was control the pressure . I by then had a vesuvius pressure profile machine as well which actually controlled pressure using the pump. Not the only way to control pressure but a real way of directly controlling pressure by changing delivery against the resistance. So to see if i was missing something i went ahead and fitted the flow control valve to the synchronika for a couple of weeks and sold it on after returning the machine to stock control.

With practice you can achieve what you are aiming for but requires you to preempt when to adjust the valve. When you want pressure to drop you need to close the valve further than you think to allow pressure to drop due to the lack of flow but start to open it very slowly prior to hitting aim point as you now require some extra flow to restore the pressure .

I’m not the best teacher or at trying to explain this and hope it sort of makes sense.

You are not changing pressure between the pump and valve, just between the valve and puck which is permeable so you seem to be controlling pressure by actually controlling flow…..

GgregE · 27 May

Adrianmsmith @DavecUK and @Cuprajake

Thank you for the comments on the flow control/pressure mechanics. What a difference 48 hours makes. I have since been able to use the flow control to my liking and understand the variables better based on your feedback. Don’t want to call myself an expert by any means just yet, but the shot I have been pulling using the flow control has been the best shot I have ever made. I’ve been preinfusing for like 20 seconds at 2 bars of pressure. Then I fully open it before tapering back down until I get my desired 34-36 grams out. The difference in body and taste compared to the normal fully open shot is the most noticeable for me, which I am thinking has to do with the off-gassing of the CO2 during the longer preinfusion phase. The beans are very newly roasted (5/19) so I was reading that it may be good to do that longer preinfusion. Long story short, it has finally started to click. The main issue for me was just getting used to the behavior of my specific flow control unit. Thanks all!

Adrianmsmith · 27 May

gregE

Thats good news ….. to quote Leonard (Cohen’s, not Nimmoy) …… 🤭🤪

Hallelujah!! ☕☕

PPortafilterProcrastinator · 12 Jul

My minima has developed a tiny leak from the rear of the pressure gauge.

Any hints or tips before I bundle in?!? Assume it might just need sealing, but could be an issue I’m completely unaware of.

Adrianmsmith · 12 Jul

It could just need taking out and a small wrap of ptfe or new o ring if yours has one or alternatively the pressure gauge bourdon tube (the bent copper tube inside) may have failed in which case the gauge will need replacing.

The first step is to ascertain if water is coming out of the threads where it screws in to the group or out of the gauge case …..

And……

Dont use the pressure gauge body to unscrew it. Use the correct spanners….. typically very thin ones!!

DavecUK · 12 Jul

Adrianmsmith The first step is to ascertain if water is coming out of the threads where it screws in to the group or out of the gauge case …..

Absolutely the above and undo using this nut! If it has an O ring, PTFE tape will still work fine.

PPortafilterProcrastinator · 12 Jul

@Adrianmsmith @DavecUK

Thank you both, that’s great. I’ll take some pics once apart.

@Adrianmsmith where did you get the thin spanners from?

Won’t be until next weekend as building a shed this weekend. Not the weather for it!

DavecUK · 12 Jul

PortafilterProcrastinator They look like shower door spanners, or perhaps bicycle ones?

DDusk · 12 Jul

Bicycle cone spanners are narrow

GgregE · 16 Jul

For some reason one of your videos @DavecUK is escaping me but I just got back from a two week vacation. I had done a full back flushing clean before I left. Any best practices i should do on the machine before using it after two weeks?

DavecUK · 16 Jul

gregE Do you have the later model with drain valves?

PPortafilterProcrastinator · 16 Jul

Spanners arrived early so I got to work!

Wrapped a few turns of PTFE around the thread but it leaks worse than ever! Irony being I am clearly a massive spanner!

Adrianmsmith · 16 Jul

PortafilterProcrastinator those threads need properly cleaning befor you even buy the ptfe never ming use it!

I can’t lie so im not going to comment about your spanner comment. 🤢

PPortafilterProcrastinator · 16 Jul

Adrianmsmith Haha, oh yes, these were taken when I first took it apart. All thoroughly cleaned before I did anything else.

I think it must have been a liquid sealant as the gauge doesn’t tighten, it just hits the inside of the group that you can see.

It now doesn’t leak - but this is equally unacceptable! All too late getting into this now, so I’ll have to be offended by the gauge until I can spend some time on it at the weekend.

DavecUK · 16 Jul

PortafilterProcrastinator It now doesn’t leak - but this is equally unacceptable! All too late getting into this now, so I’ll have to be offended by the gauge until I can spend some time on it at the weekend.

Put enough PTFE so it’s tightish all the way in and don’t do it up fully, it doesn’t create a better seal, quite the contrary. Just stop when it’s most of the way in and the gauge is level.

Adrianmsmith · 17 Jul

DavecUK

@PortafilterProcrastinator

Just to continue Dave’s point here if you are not over familiar with thread sealing especially with something like this pressure gauge, it is the actual contact of the PTFE tape against the faces of the threads on the internal and external part that stop it from leaking.

With the correct amount of PTFE, it will be easy to get the gauge in the correct orientation.

On my synchronika I once set mine so the number nine was at the top but my wife soon made me change it 🤪🤔😶

There is a misconception that it has to go all the way to the bottom but in this case there is nothing to seal / bottom out by going all the way to the bottom.