MediumRoastSteam

My two hole tip was on very tight, so much so I thought threadlocker was used (it wasn’t). I used a lot of electric tape around the tip and pliers instead of a wrench to get it off. Tip was scratched but I had spare. I didn’t end up needing a vice but was considering it beforehand.

@PortafilterProcrastinator Bella Barista have the Minima two hole tip for £5 + del if you want to rule out anything being stuck and nothing else is working.

https://www.bellabarista.co.uk/catalogsearch/result/?q=Minima%20tip

I know the expobar 2 and 3 hole steam tips also fit. But these are in fact even more powerful than the 3 hole stock Minima tip:

https://www.theespressoshop.co.uk/Mobile/en/Expobar-2-Hole-Steam-Tip--Oring---30370185/m-m-4531.aspx

The Izzo Duetto tips fit as well:

https://www.bellabarista.co.uk/izzo-duetto-steam-tip-set.html

Interestingly according to the BB website the Izzo Duetto tips are compatible with the Bianca, which would imply the Bianca tips will fit the Minima. The Bianca tips have smaller 1mm holes which I believe will help better control the amount of air you introduce into the milk. They have 2 and 4 hole tips - something I might try:

https://www.lamacchinadelcaffe.com/en/cartsearch/index.html?q=2200108

      HVL87 Intersting none of those have the little metal tube that sticks out the top. Not having that would make it easier to see inside for sure.

      Some of those prices are a little eye watering for a little old steam tip.

          PortafilterProcrastinator I always wondered why that metal tube was sticking out at the end. If I remember correctly @DavecUK mentioned it is useful for no burn steam wands - clearly redundant for the Minima. I do find the steam a bit “cleaner” from the expobar tip, but don’t think it really makes a real world difference.

          They are a bit on the pricey side - the expobar tips are good but only if you’re steaming larger quantities of milk. I have settled on the stock minima 3 hole for a 350ml pitcher, although might try the Bianca tip if it fits.

              HVL87 Looks to be all one piece of metal so can’t take it off. That’s a shame.

              I’d be fascinated to see a video of you or @Rob1 steaming with the 3 hole tip in a 350ml pitcher to see the technique. Do you open the valve up all the way?

                  PortafilterProcrastinator

                  I shove the wand in the milk and open the valve all the way. The angle is pretty much straight down and slightly off centre. I let it hiss for about 1, maybe 2 seconds, and then submerge. You can angle the jug and aim further towards the side. Don’t over think it, just think how much air you need in the milk (doesn’t take long with a three hole tip and a small quantity of milk) and then you’re just heating and mixing….it doesn’t have to swirl, it can tumble around and wind up the same in the end.

                      12 days later

                      @DavecUK Thinking about things in the time before I am going to be able to test/ experiment and had a thought about the vacuum breaker.

                      If the VB isn’t working correctly and opens when the steam valve is opened, would that draw cold air in through the VB and then mix it with the steam and push it out through the wand?

                      I need to run the machine with the top off to see if I can tell what it is doing during warmup and steaming etc.

                        PortafilterProcrastinator If the VB isn’t working correctly and opens when the steam valve is opened

                        If there’s pressure inside the boiler, the vacuum breaker will remain close, by design. It’s mechanical, there’s no springs, and positive pressure pushes the plunger up. Unless all the pressure goes to zero when you open the steam wand, in which case no steam would come out either, the vacuum breaker would remain shut. You might be overthinking this one. 😊

                            MediumRoastSteam I might, but it just isn’t making sense. I am also learning a lot about how my machine works - to say I am starting from a position of complete ignorance is an understatement. So I will be all the better for the experience.

                            Water produces steam at 99/100 degC at standard atmospheric pressure (please correct me if I am wrong). As pressure increases, the temperature required for water to produce steam increases.

                            So if I am getting hot (let’s put my potentially erroneous and confusing temp reading to one side for the moment) spluttery water out of the hot water tap and steam out of the steam wand, it has got to be above 99/100 degC. If the VB closes at very low pressure, then the temp of the water has to be above this to continue to produce steam.

                            How much above is one question. The temp display might say 130degC, but it could be anywhere between 100 and 130. So I am going to be testing that by swapping the temp sensors.

                            What I have never done (and will do once all this is resolved) is test the steam power at say 110 and 120degC to see what the impact on the steam power is and affect on milk. At the moment it takes me 15-20s to pass the LH MJ test, which doesn’t seem too long, so if the steam is hot is there then a question around the pressure it is coming out of the steam wand?

                            My question on the VB stems from the amount of pressure required to close it. If opening the steam wand leads to a drop in pressure in the SB (which I am assuming it must) then can this theoretically lead to the VB opening? If it can, then would this lead to a drop in steam pressure but still allow the steam to heat the milk to the ‘correct’ temperature.

                                PortafilterProcrastinator My question on the VB stems from the amount of pressure required to close it. If opening the steam wand leads to a drop in pressure in the SB (which I am assuming it must) then can this theoretically lead to the VB opening? If it can, then would this lead to a drop in steam pressure but still allow the steam to heat the milk to the ‘correct’ temperature.

                                They are all good questions.

                                On my machine - and others I’ve owned - the VB closes as the temperature inside the boiler is around 100C. Last time I paid attention to that it was around 99C or 101C, I can’t remember exactly. I can let you know tomorrow when I make my morning coffee :-)

                                If the vacuum breaker were to open when you open the steam wand, you would hear and see steam coming out from the top of the machine, as if another steam wand would be open. I personally believe that what you describe is not possible, as, if there’s steam, then there’s water under pressure inside that boiler and the vacuum breaker will remain close. By all means though, take the top off your machine and check.

                                  PortafilterProcrastinator If opening the steam wand leads to a drop in pressure in the SB (which I am assuming it must) then can this theoretically lead to the VB opening?

                                  Not if the VB works. A vacuum breaker has one end of the circuit at atmospheric pressure (plus or minus tank depth pressure, but that’s negligible). For the valve to open, pressure on the other side of the valve has to be lower than atmospheric - which is what happens when a steam boiler that has been used (and thus is not full of water) cools down: the steam condenses and the water shrinks, resulting in a pressure below 1 bar, the VB opens and lets “whatever is on the other side of the VB” (air or water) in.

                                  If that were the case, the water in the boiler (liquid or steam) would be below atmospheric pressure, so definitely be cool…. but you wouldn’t get any flow through the steam wand, as the “open” end of the steam wand is at atmospheric pressure!

                                      CoyoteOldMan Thank you, again, makes perfect sense and see why my previous thoughts were wrong.

                                      I’ll be happy once I can get an accurate temp reading on the hot water, but looking like the sensor as temperature seems to be the prime suspect.

                                          PortafilterProcrastinator NTCs can be fickle. Looks OK, tests OK (in terms of electrical continuity/resistance at 20 °C), then you have a gas bubble or a crack in the potting resin and when heated it reads all over the place… at least it shouldn’t be expensive or difficult to replace!

                                              CoyoteOldMan CoyoteOldMan Thank you, really appreciate the advice.

                                              Paolo has asked me to swap the temp probes from each boiler over just to make sure nothing else is going on.

                                              Once he’s got back to me on the best way to get them out and whether I need to empty the boilers etc I’ll give it a go!

                                                  10 days later

                                                  I’ve not had a chance to look at the machine properly yet as there have simply been more important things going on in life, but I continue to use it daily for both espresso and lattes (well, hot milky coffee). Probably the reason for bouncing around in my head, frustrating I can’t just get on with it, but that’s life.

                                                  Following a saga with getting batteries for a sugar thermometer, I was finally able to better test the temp today. The highest reading I got (water running into an already hot milk jug) was 92deg. Boiler set to 130. However, see below - as this is a reading taken following a change in behaviour.

                                                  Interestingly milk steaming has been more variable. Certainly not what it used it used be. But. Beginning of this week I was steaming milk and there was a sudden and noticeable change in the noise and force of the steam. This was mid-steam. Milk was steamed better. But it varies still.

                                                  I have cleaned the steam wand a good few times with PulyMilk. The next step is to run some citric acid through the service boiler and then swap the temp probes over. I will hopefully get time to do this over the next couple of weeks.