So this happened again this morning, which caught me off guard as it hasn’t happened for a while. I will describe as best I can.

  • Service boiler switched on

  • Life/ Pop out to get milk (so service boiler on for 30/35 mins before I touch it)

  • Open hot water tap, notice no spluttering/ not super hot - service boiler temp shown as 125/126 degrees

  • Take c.500ml water out service boiler in two goes (I did weigh it, was within a couple grams of 500) (stick my finger in it, ’oh, that’s hot’ but certainly not ’oh s**t that’s hot’)

  • Pump runs, service boiler fills, I top up the water tank, boiler finishes filling, but the temp shown does not change

  • I do not hear the usual noises when the heating element kicks in to re-heat

  • I turn on the steam, a normal amount of water comes out and then steam - it looks like the normal amount of steam I get, but I cannot be certain it is the same ‘strength’/ force etc

  • The heating element then kicks in and I notice the temp shown has dropped to 112/113 degrees

  • I give the service boiler time to come up to temp whilst I grind some beans and prep portafilter etc (5 mins maybe, just to be sure)

  • I open up the hot water tap, a small amount of hot water, then the normal spluttering/ super hot water - this was normal behaviour

  • Pump runs, service boiler fills

  • Normal service resumes, I crack on and there is no other odd behaviour

I’ll be honest, I am at a bit of a loss. I have not done anything different with the machine recently.

    I’ve had something similar happen with the steam temperature recently on my Minima. It seems to have resolved itself by me leaving a longer warm up time for the service boiler whereas it used to be good to go after 10 mins

    PortafilterProcrastinator I’d be guessing but it could be a faulty temperature sensor miss reporting the temperature to the Gicar box

    PortafilterProcrastinator Take c.500ml water out service boiler in two goes (I did weigh it, was within a couple grams of 500) (stick my finger in it, ’oh, that’s hot’ but certainly not ’oh s**t that’s hot’)

    This bit is confusing because it uses steam pressure to get the water out, so by definition, it would have to be in excess of 100C??, and the water would feel boiling hot. Try boiling a kettle, filling a mug of water and dipping your finger in it, would you class that as hot, or shit that’s hot? This gives me some context.

    Your next bullet says pump runs service boiler fills…was this pump running while you were drawing water, I ask because it’s not possible to draw 500g without activating the pump, or shouldn’t be?

    Heres the logic and contradictions I am struggling with for you to consider:

    • Water not hot e.g. not at 98C+ (how did it exit the boiler, did the pump push it out, did water expansion push it out, water expansion seems unlikely to push that amount out (40ml perhaps)
    • Vacuum breaker stuck, air heats and expands, this air expands enough to push water out at way below 100C (unlikely, normally there is not enough pressure to push much out, also temp sensors not fooled by this like pressure stats, they know it’s not at the right temp)
    • Faulty temperature sensor (this is a possibility, although still doesn’t explain how the water came out “not really hot”, for anyone in doubt, set your service boiler temp to 105C and see what happens and whether the water is hot).
    • faulty temp sensor, faulty Gicar, overfilled boiler and pump runs pushing water out…that’s (3 simultaneous faults, which is again not likely)

    Above are the things I’m thinking about and I can’t seem to make sense of the problem, in those thoughts might be some clues to help you remember something, or notice something you didn’t perhaps realise might be important.

    PortafilterProcrastinator The heating element then kicks in and I notice the temp shown has dropped to 112/113 degrees

    Because it did an autofill with cold water.

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            DavecUK Thanks Dave, sorry for slow reply.

            DavecUK This bit is confusing because it uses steam pressure to get the water out, so by definition, it would have to be in excess of 100C??, and the water would feel boiling hot. Try boiling a kettle, filling a mug of water and dipping your finger in it, would you class that as hot, or **** that’s hot? This gives me some context.

            I will stick my finger in some boiler water tomorrow - been a bit hot (and busy!) today.

            This is also the crux of my bafflement with the issue. Heating element at the bottom, hot water comes from the bottom, steam comes out the top, but it simply isn’t ‘boiling’ hot.

            I am going to get a kitchen thermometer so I can test it the next time it happens.

            DavecUK Your next bullet says pump runs service boiler fills…was this pump running while you were drawing water, I ask because it’s not possible to draw 500g without activating the pump, or shouldn’t be?

            The pump did start running whilst I was filling. This is why I was confused the temperature didn’t drop on the display. I waited until the pump stopped filling before I opened the steam valve, but the temp hadn’t dropped.

            DavecUK Above are the things I’m thinking about and I can’t seem to make sense of the problem, in those thoughts might be some clues to help you remember something, or notice something you didn’t perhaps realise might be important.

            All noted, thank you. I will also set the service boiler to 105 and see what happens.

            On the vacuum breaker point, I will have to take the top off and watch whilst it heats up to see what’s going on.

            DavecUK Because it did an autofill with cold water.

            Yes, absolutely - my observation here was that the display temp didn’t drop until after I’d opened the steam valve, even though the pump had run and filled the boiler - as if opening the steam valve jolted something and got everything working/ going again.

            I’ve not had the service boiler on today, but will do tomorrow.

                        @CoyoteOldMan @DavecUK

                        So happened again today. Screaming (excited) children meant no video.

                        I’d confidently call the first draw of 240ml luke warm, but there was still some steam - albeit not normal power at all.

                        I only drew 240ml before opening the steam valve. Steam tapered off but some kept coming.

                        Pump ran and filled the boiler throughout as normal.

                        I waited for temp to get back to 125deg whilst I ground and poured two shots.

                        I then steamed 190g milk - huge difference. I got it very hot - passed the LH Michael Jackson test. But it was as thin as cold milk. The screaching/ shredding sound was a lot harsher than it normally is.

                        I will email ACS and see what they say.

                          PortafilterProcrastinator I suspect they will suggest changing the thermal sensor…Was this the one that was purchased from Black Cat Coffee, if so, they get a special price, because they buy out the warranty and any replacement part should really be from them?

                          Bought direct from ACS it’s a 2 year parts warranty.

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                              PortafilterProcrastinator DavecUK Bought direct from ACS - new heating element means a new boiler doesn’t it?

                              I guess I’ll get to learn my machine on a whole new level!

                              My bad, I meant thermal sensor, my hands typed something else 🤣

                              However just for peace of mind in the unlikely event the incolloy 800 element ever failed…see below.

                              Fortunately it shouldn’t be too expensive, read the review, specifically this bit:

                              https://coffeeequipmentreviews.wordpress.com/2019/03/06/acs-minima-final-production-machine/

                              Now it was in 2019 and in fairness prices of parts have increased by 20% (Covid) and probably 3 years of normal inflation on that….so you could be looking at up to a 30% uplift.

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                                  13 days later

                                  So I have been doing some experiementing and I still can’t work out what might be going on, but it has led to another question/ thought.

                                  I have started leaving both the brew and service boiler switched on, so they both come on with the timer plug.

                                  Brew and Service boiler come on

                                  I have noticed the service boiler does overshoot a little when first heating up. I need to ask ASC if this is intended.

                                  After approx. 20mins I vent the steam wand for a few seconds

                                  Service boiler temp drops more than normal - down to maybe 122 degrees (according to the display, acknolweding the actual temp might not be the same)

                                  Machine normally then gets left for another 25mins or so before I make the drinks

                                  On the face of it, everything looks to be opperating normally - but, the milk just isn’t steaming the same way.

                                  I have previously always struggled not to over steam milk with the 2-hole steam tip.

                                  At the moment, I am struggling to get much more than hot milk - no thickening/ aeration seems to take place and I don’t get the same volume increase that I used to. I get to/ past the LH MJ test in a similar time, so the heat seems to be there.

                                  I did swap to the three hole steam tip that I have got and it pretty much blew the milk out the pitcher (190ml milk in a 350ml pitcher) - very frothy milk (massive bubbles), but doesn’t tell me much about what might be going on.

                                  I switched back to the two hole and the story was the same - hot but thin milk.

                                  I am going to take the case off and have a look inside.

                                  Should I take the steam want off and check for blockages? Could a blockage cause this?

                                  Cheers

                                    PortafilterProcrastinator Should I take the steam want off and check for blockages? Could a blockage cause this?

                                    A blockage in the tip definitely could, especially if it’s inside behind the holes! If you have an outie tip and not an innie, it can make it impossible to see any crap caught behind the holes and difficult to clean.

                                    When steaming, it’s very very important to always have the tip slightly angry and hissing before it enters the milk and as soon as it enters, you should be opening the valve. When finishing steaming, always blast steam out of the valve, close gently, submerge in the milk jug full of cold water, wait for the suck and then expel the water sucked up with more steam.

                                    Even more important with the kind of valve used on the minima…close it super gently, with a jug under it. it will drip after minute or so and you will think you didn’t close it…but you did. As it cools after a minute or so…the metal contracts and the seat lifts off allowing steam through, just close it again super gently until it goes quiet. It won’t drip again (we still steam the old way). If you do this, these older valves have an almost infinite life.

                                    Most people just close them really hard so they won’t drip and need to replace the stem with teflon pad in it after 3-5 years.

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                                        DavecUK Thanks Dave,

                                        I’ll soak the steam tip - any advice before I try to take the steam arm off?

                                        I will pay more attention to my technique as well

                                        Also - noted on the knobs. I try to be as gentle as possible and back off after close to try and find the sweet spot.

                                            PortafilterProcrastinator Before you start dismantling the arm, I’d give a good soak to the tip… the fact that you are getting “explosive power” with a 3-hole tip (that presumably you aren’t using much), but a weak, watery steam with a frequently used 2-hole makes a blockage in the steam arm and boiler sound unlikely.

                                              PortafilterProcrastinator pretty much blew the milk out the pitcher (190ml milk in a 350ml pitcher) - very frothy milk (massive bubbles), but doesn’t tell me much about what might be going on.

                                              This is an issue with technique. I use the 3 hole with less milk in the same size jug no problem. The milk is pretty much perfect with little to no effort in about 15 seconds.

                                                  Thank you for everyone’s input here.

                                                  I soaked the steam tip in pulycaf but the result was the same today.

                                                  I am going to descale the service boiler just in case (I use lockhills and flush regularly, not descaled yet and had machine since March).

                                                  Then I will try again.

                                                  I will try to do some videos too, but trying to get even 10mins peace and quiet is hard at the moment!

                                                    PortafilterProcrastinator I soaked the steam tip in pulycaf but the result was the same today.

                                                    That often won’t shift the crap, do you have a photo of the tip type it is…I don’t mean a photo of it on the wand, but off the wand.

                                                    It’s possible the tip is still blocked.

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