# ECM Mechanika Slim high boiler pressure



## DayZer0 (Feb 23, 2019)

Hi ECM owners

My Slim idles at 1.45 bar (but occasionally drops as low as 1.3 before you hear the heater kick back in).

The instructions say the machine heats up to 1 to 1.25 bar range. I did email ECM who said 1.45 is still within tolerances.

Anyway I wanted to ask what experience others have with this? My only comparison so far is based on looking at photos/videos machines online and it rarely looks like the boiler pressure is that high.

I'm a beginner so reluctant to start opening up the machine and experimenting, so hopefully everything is fine, just want some reassurance from those with more experience.

Thanks


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## MediumRoastSteam (Jul 7, 2015)

Seems a tad high. Are your shots too hot? Is your cooling flush too long?


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## L&R (Mar 8, 2018)

I would reduce the pressure to 1.1-1.3 cycle, procedure is not so difficult


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## richwade80 (Aug 25, 2017)

I had heard that ecm machines came with the pressure slightly high. I got mine from Bella Barista, who I believe sometimes tweak them before sending out.

Anyway, I tweaked mine afterwards and asked BB about doing it. This is what they said;

'I have the machine switched on when doing this but bear in mind when poking around inside that there is live electrics. Remove the top lid by removing the 4 x Allen key bolts and you will see the pressure stat in clear view. (see image below)

Using an insulated screw driver just turn the pressure stat a ¼ turn anti clockwise, then purge the steam for 10 seconds to activate the element and wait and watch until you see/hear the pressure stat click the element off. Clockwise turns the pressure up - Anti clockwise turns the pressure down.'

For what it's worth, a quarter turn adjusted the pressure by about 0.2 bar.


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## DayZer0 (Feb 23, 2019)

Thank you for the detailed instructions.

Before I try and make an adjustment I wanted to check if you all think it's worth it at all.

Here is a link to a cooling flush this morning after circa 30 min idle (you can also see the pressure reading).











Is this normal?

Needs at least 100ml flush but can't say I'm exactly sure when I've flushed enough. I'm using bottled water so if changing the pressure improves this then that's a big bonus.

I assume the downside is losing steam pressure if I reduce, but is it actually noticeable?

Thank you!


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## kennyboy993 (Jan 23, 2017)

Yeah that's too much for a modern ECM.

The slim is tank only isn't it - so I'd recommend topping out at the 1.25 mark that should be fine.

You stop flushing as soon as the flash boiling stops generally.

Note that with a pstat there's a 'bottom out' and 'top out' pressure - the lower point at which it will click-on and the upper pressure where it clicks-off. Ensure the 1.25 or whatever u set is the click-off, the upper limit.

When adjusting the pressure it can take 30 mins or so to settle down and only then will u see if you've got it where you want it - so after making an adjustment leave it for a while to settle and check it's where u want it

A modern ECM has a tuned heat exchanger and should be a relatively short flush even after 30 mins.


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## DayZer0 (Feb 23, 2019)

Thank you

I can try adjusting down to 1.25, do you do this with the machine on or off?

Regarding the flash boiling point. Do you think i was flushing too long in the video?


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## kennyboy993 (Jan 23, 2017)

DayZer0 said:


> Thank you
> 
> I can try adjusting down to 1.25, do you do this with the machine on or off?
> 
> Regarding the flash boiling point. Do you think i was flushing too long in the video?


I used to do it with the machine on though obviously that has risks.

It sounds and looks to me the flash boiling stopped around 14 seconds?

The second little flush is unnecessary and will cool the group even more ;-)

Lots of HX reading on here - good learning


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## MediumRoastSteam (Jul 7, 2015)

DayZer0 said:


> Thank you
> 
> I can try adjusting down to 1.25, do you do this with the machine on or off?
> 
> Regarding the flash boiling point. Do you think i was flushing too long in the video?


Turn the machine off on the wall. Adjust. Turn it back on again. There's absolutely no point to do so with the machine on. In fact, the machine off will help you by cooling things so you can see when it's kick in again.


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## DayZer0 (Feb 23, 2019)

Ok. Thanks all.

Just under a quarter turn seems to have got me to a 1.3 to 1.1 cycle. I'll report back if it makes a difference to flush or steam!

Thanks


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## L&R (Mar 8, 2018)

In the video above I see boiling water till the end.


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## DayZer0 (Feb 23, 2019)

Hi all

I reduced the pressure this afternoon. It's now cycling up to about 1.3 and then cools off to about 1.1.

I then repeated this morning's experiment. The machine had been idle for well over an hour.






The cooling flush seems about the same. But perhaps it was unrealistic to expect this to have an effect?

I suppose while ever the steam boiler has a higher temp than desired for brew water, you will always end up super-heating a certain volume of water in the brew pipe? Perhaps I have to live with a 100ml flush after a long idle and that the lower boiler pressure may only make a bit of difference when comparing shorter idle times, say 15 mins?

In that case, is there really any downside then to just running a 1.5 bar pressure as I had before?

Thank you!


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## kennyboy993 (Jan 23, 2017)

I would lower it more if it was mine - it will have a direct effect on the amount of flash boiling.

Not see the vid though if it's like the last one it's too much - these ECM run cool relative to other perhaps older hx machines and are noted for their small flushes.

A lot of people run them topping out at 1bar even though in my view that's a little low - perfect for the first shot though rebound is too slow.

Running at 1.5 will make it a steaming monster and the flush would be too big.

Keep experimenting - you'll be changing the pressure on it constantly for the next 6 months anyway ;-)


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## ashcroc (Oct 28, 2016)

Please remove that warning sticker from the grouphead before it etches itself onto the chrome! You know it's gonna be hot when up to temp.

It may also be an idea to get a grouphead thermometer like an erics or coffee sensor so you know when you've flushed enough.


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## DayZer0 (Feb 23, 2019)

kennyboy993 said:


> .
> 
> Keep experimenting - you'll be changing the pressure on it constantly for the next 6 months anyway ;-)


Yes, I think I've started down a dark path today!


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## DayZer0 (Feb 23, 2019)

ashcroc said:


> Please remove that warning sticker from the grouphead before it etches itself onto the chrome! You know it's gonna be hot when up to temp.
> 
> It may also be an idea to get a grouphead thermometer like an erics or coffee sensor so you know when you've flushed enough.


These look interesting. I actually watched a few youtube videos of the Coffee Sensor and similar and in most cases people were flushing about as many seconds as I am having to do. Perhaps I just need to find peace with the water wastage. I will also try lower pressures as Kennyboy993 suggested.


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## richwade80 (Aug 25, 2017)

It's a good path... it screws your head sometimes, but once you learn it, it's quite satisfying.

FWIW it sounds like your second video is not far off?

The first video you can hear flash boiling (bubbling) for quite some time, till about 15s into the video. In the second it seems way shorter, but you still kept flushing anyway.

I flush to the end of flash boiling, usually less than 50ml, maybe only 30-40ml sometimes. I then lock and load, and pull the shot ASAP. I do not like wasting water, especially bottled - because I'm tight!

A group thermometer does not solve everything, but it does make it a lot more transparent. It does help with consistency.

Enjoy messing about.


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## DayZer0 (Feb 23, 2019)

richwade80 said:


> It's a good path... it screws your head sometimes, but once you learn it, it's quite satisfying.
> 
> FWIW it sounds like your second video is not far off?
> 
> ...


Thanks. Perhaps I was judging it wrong. Were you going off the roaring sound?

I had been trying to watch the bubbling out the group head but when I watched back and just listened the second video hissed less.


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## richwade80 (Aug 25, 2017)

DayZer0 said:


> Thanks. Perhaps I was judging it wrong. Were you going off the roaring sound?
> 
> I had been trying to watch the bubbling out the group head but when I watched back and just listened the second video hissed less.


That's it! (At least I hope so, or I've been doing it wrong)

It's water boiling on contact with the air essentially. It sounds like squeezing air though a wet sock. When it stops, you're good to go.

Note that there are other ways of using HX machines - the long flush and other methods. If you're on bottled water, you'll probably want the 'flush and go' technique.

Look it up for other advice as well.


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## MediumRoastSteam (Jul 7, 2015)

And this thread illustrates well the main reason I moved away from an HX machine to a Dual Boiler. I could not bear 150ml+ of bottled water being wasted twice a day.


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## richwade80 (Aug 25, 2017)

MediumRoastSteam said:


> And this thread illustrates well the main reason I moved away from an HX machine to a Dual Boiler. I could not bear 150ml+ of bottled water being wasted twice a day.


In the grand scheme of things, bottled Waitrose water is still bloody cheap. But I do know what you mean. Buying bottled water suddenly makes you very conscious of it. If I was plumbed in, I probably would not care. I'd 'flush my arse off' so to speak.

I use my flush water to heat cups so to be honest couldn't make coffee using less water anyway.


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## DayZer0 (Feb 23, 2019)

As an aside. When I had the machine lid off and turned it on. As it was heating up, there was a very small spurt of water out of a metal valve on the boiler, which it then seemed to seal itself. I took this photo straight after and you can see the droplets

Is this normal?


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## MediumRoastSteam (Jul 7, 2015)

I think so. It will just evaporate eventually.

On the Profitec Pro 700, the one I had had a silicone hose which would take it to a vent just above the drip tray.


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## jegersmart (Dec 8, 2019)

All, just get a Big Berkey waterfilter. They cost £250 or so but the 2 filters supplied last 10-12 years or 22000litres of water. It works out at around 2p per liter initially, the replacement filters are £120 so just gets cheaper. That way you don't use water that has been standing a plastic bottle for years, avoids more plastic (or glass) bottles having to be made etc etc.


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## DavecUK (Aug 6, 2013)

Totally normal just the vacuum breaker sealing up. As long as you use good quality water it won't give you any trouble. I'd personally like to see all manufacturers move to the newer memory metal vacuum breakers. My next little hobby horse....


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## DayZer0 (Feb 23, 2019)

jegersmart said:


> All, just get a Big Berkey waterfilter. They cost £250 or so but the 2 filters supplied last 10-12 years or 22000litres of water. It works out at around 2p per liter initially, the replacement filters are £120 so just gets cheaper. That way you don't use water that has been standing a plastic bottle for years, avoids more plastic (or glass) bottles having to be made etc etc.


Thanks for the idea. I just looked then up but sounds like they don't soften water.

Sent from my SM-G975F using Tapatalk


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## DayZer0 (Feb 23, 2019)

DavecUK said:


> Totally normal just the vacuum breaker sealing up. As long as you use good quality water it won't give you any trouble. I'd personally like to see all manufacturers move to the newer memory metal vacuum breakers. My next little hobby horse....


Thank you!

Sent from my SM-G975F using Tapatalk


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## jegersmart (Dec 8, 2019)

DayZer0 said:


> Thanks for the idea. I just looked then up but sounds like they don't soften water.
> 
> Sent from my SM-G975F using Tapatalk


 Hi Day

Strange, I get very little build up in my kettle after I started using the Berkey about 7 years ago, before that it was many times as bad!


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## DavecUK (Aug 6, 2013)

jegersmart said:


> Hi Day
> 
> Strange, I get very little build up in my kettle after I started using the Berkey about 7 years ago, before that it was many times as bad!


 I keep saying this on threads about water...it's not just about limescale...there's other things in water including that stuff called dry residue!


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## DayZer0 (Feb 23, 2019)

DavecUK said:


> Totally normal just the vacuum breaker sealing up. As long as you use good quality water it won't give you any trouble. I'd personally like to see all manufacturers move to the newer memory metal vacuum breakers. My next little hobby horse....


Dave can I ask you a technical question. I've been thinking about flushes and wondered if the flush volume will always be the same regardless of boiler pressure? Isn't the volume of water sitting in the heat exchanger always the same and it will always super heat eventually.

This might mean the flush volume after a short wait will be different and different boiler temps. But would reach an equilibrium eventually.

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## DavecUK (Aug 6, 2013)

DayZer0 said:


> Dave can I ask you a technical question. I've been thinking about flushes and wondered if the flush volume will always be the same regardless of boiler pressure? Isn't the volume of water sitting in the heat exchanger always the same and it will always super heat eventually.
> 
> This might mean the flush volume after a short wait will be different and different boiler temps. But would reach an equilibrium eventually.
> 
> Sent from my SM-G975F using Tapatalk


 Sorry it's a long answer but it's complicated (the reasons) for such a simple thing as a flush. Yes your reasoning is almost correct but please read on.

I wish it was so simple and one of the reasons the HX machines I used to test in the old days were such a PITA to do. Yes the volume of water in the HX is the same so if we talk about exactly the same machine an increase in boiler temp causes an increase in HX thermosyphon temp. They usually (should) have injectors fitted for incoming water, this will cause some mixing and heating as it enters and the water that comes down the group pipes is not quite at thermosyphon temperature....as it enters it's being reheated in the HX and the heating elements kick in. This means after the flush the water is heating right back up again. This first effect varies a lot by machine...an Andreja might require a 30 second wait after flushing, an Izzo might be 10 seconds or pretty much flush and go by the time the PF is loaded. So boiler temperature affects this step.

The second area affected is the group and if you like, the metal in the system, the air in the case (everything that isn't water). This all serves to help maintain heat, the group temperature will have a direct effect on shot temperature. When you flush the group temperature comes down, but if you start off hotter it doesn't come down as much for an Identical flush starting from a lower temperature.

Now these effects above are subtle but will affect initial brew temperature as the water hits the coffee and, intra pour stability. With a small change in temperature (1-2C) then you wont see too much difference, but moving from 123 to 130 you might see quite a lot. *The HX design in the particular machine and any thermosyphon restriction, size of thermosyphon pipes, insulation, temperature control mechanism etc.. will also affect greatly how it reacts to changing boiler temps. *There are a few machines so bad that if the boiler temp is too high, they become very difficult to flush down and warm up again almost instantly. One is coming off the market as a new machine the other is still on the market and unsuspecting owners have no idea (initially), usually it takes about 12 months for the penny to drop.

The other test I do when temperature testing is an "on test". Warm up machine, after warm up period say 30 minutes (flush then check shot temp), then leave it an hour (repeat), then leave it 2 hours (repeat_. Try it you will see the flush volumes increase, surprising because you wouldn't expect any real change after 1 hour. It's a super PITA when setting up dual boiler PID settings as* this and other tests* have to be repeated for each temp step from 90-96...takes lots of time.

All this is why I used to put a recommended pressure/temperature for the boiler on machines HX I used to test and write manuals for or recommend to BB. With one exception, I don't test HX machines these days. The One exception is the Lelit Mara X because it's very unusual. I had a prototype back in July last year and it failed some *special* temperature testing as it was designed to be a "better HX" that didn't need much if any flushing. In a lab that may have been true but not in the real world used like an owner would use one. They went back to the drawing board after my report and solved the problems...In January I will get a production Mara X to side by side with the prototype and I will spend time going through the differences and the journey from prototype to final production and the case off changes.....keep an eye for it on my review site and youtube channel I think you might find it interesting.

As always things are a compromise in any machine, the HX is a larger compromise but as we compromise on pressure, grind, roast level at any specific point in the shot, as long as it all works together to produce an acceptable beverage....no problem. It's when that compromise (for any element) falls way outside the reasonable parameters we start noticing a difference. So *for your specific machine I don't know the flush down volume/time, or the ideal wait period before lock and load, or the time between shots where you don't have to flush or require a reduced flush volume*.. You will have to test these things yourself. You can get a pretty good idea for free by watching the water flash off to steam from the shower screen. *If you pull a shot and then prep for a second, does it flash to steam again before you lock and load? If it does, how quickly does it calm down again (usually much faster) and it's easy to over flush as group temp changes as well. *


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## DayZer0 (Feb 23, 2019)

Wow thanks Dave. That was very interesting.

Do you or anyone have any good links to explanations of the hx system used by ECM (this machine in particular is even better). I'd be interested now in learning more about the engineering (than the very high level HX graphics you see)

In terms of the tests you describe. I think I'd need to invest in a Coffee Sensor for the group head to do that level of testing. Maybe a project for Jan!

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## DavecUK (Aug 6, 2013)

Most manufacturers don't share detailed cad of the Hydraulics and any I do have I can't really share.


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## DayZer0 (Feb 23, 2019)

Understood. I think I've realised a fundamental misunderstanding of the machine that led to my earlier question.

I thought there was a seperate water circuit used to to warm the group rather than water cycling back through the HX.

This meant I imagined a very simple system where water went straight from the tank to the HX to the coffee only when the pump was on. Hence I imagined a fixed volume of water 'sitting still' in the HX tube becoming superheated.

In reality I think the water cycles through the system and this means that when the pump starts you are also mixing super heated water with tank water. I can see how this makes the whole thing more complex to model!

Does that make sense?

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