# ACS Minima Steam Boiler - Letting out steam, loud pops



## brewd (Jun 24, 2019)

Hi all,

Hoping maybe someone could help with my ACS Minima steam boiler issues.

I returned from dropping my son from school today to find the steam boiler hissing, popping (quite loudly) and letting out lots of steam through the top of the case.

I turned it off immediately and then later on removed the top cover. I have attached a video of the machine after it was turned on again and warmed up, after the top cover was removed.
As you can see the LCD is steamed up from this morning's steam release.

Any idea what's gone wrong here?

Thanks in advance.

View attachment Steam-Boiler-Fault-1.mp4


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## ajohn (Sep 23, 2017)

@DavecUK

But you probably need to look at the valve near your indicator assuming that is the area it is coming from.


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## brewd (Jun 24, 2019)

ajohn said:


> @DavecUK
> 
> But you probably need to look at the valve near your indicator assuming that is the area it is coming from.


 Thanks, it seems to be coming from that big brass centre valve (the pops anyway):


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## DavecUK (Aug 6, 2013)

@brewd It's because there is too high a temperature by the look of the PID display...it's reading 132...but even that may be inaccurate.



Is the steam from the system dry, or really really wet?


*If you draw water from the system...draw 50 or 60ml and stop...does it autofill?*


What sort of water do you use?


How old is the machine (not just when you bought it), have you owned it from new?


The steamed up PID won't matter...that's just a display, the real heart of the PID is in the Gicar box, although you don't want to keep getting the display moist inside. if your phone can take a larger better quality photo of the top area of the machine that "might" be handy.

Depending on the answers you give above, you may have to remove the temperature probe and have an inspect of it......for now I'd advise running with the steam boiler off until you know what's going on.


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## brewd (Jun 24, 2019)

DavecUK said:


> @brewd It's because there is too high a temperature by the look of the PID display...it's reading 132...but even that may be inaccurate.
> 
> 
> 
> ...


 Thanks for your offer to help @DavecUK.



Steam seems dry


Yes, it does autofill after drawing some water from the system


I have only used Evian in the machine apart from a brief period using Waitrose water.


Now you mention it, it does appear to be overheating. You can hear it stop heating once the steam boiler reaches 127, but somehow it begins heating up again a few minutes later. I'm pretty sure this morning I saw the temperature jumping between 110-ish and 130-something so perhaps the probe is at fault. Where can I find the temperature probe?


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## DavecUK (Aug 6, 2013)

brewd said:


> Thanks for your offer to help @DavecUK.
> 
> 
> 
> ...


 Answer all the questions (e.g. about ownership)...it really might save you a lot of hassle...Looking at the Evian label, I wouldn't use that in my machine....far too high in minerals.


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## brewd (Jun 24, 2019)

DavecUK said:


> Answer all the questions (e.g. about ownership)...it really might save you a lot of hassle...Looking at the Evian label, I wouldn't use that in my machine....far too high in minerals.
> 
> 
> View attachment 55228


 Just realised I had a complete brain malfunction there. I mean *Volvic*, not evian!


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## brewd (Jun 24, 2019)

DavecUK said:


> How old is the machine (not just when you bought it), have you owned it from new?


 Sorry @DavecUK, this one wasn't there when I replied. Yes, I've owned from new since June 2019, purchased from Bella Barista with 4 year warranty.

Only *Volvic* and Waitrose water used in it.

I've attached a higher quality image.


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## John Yossarian (Feb 2, 2016)

Wait for @DavecUK but comparing both boilers the temperature probe should be the one on the right, just behind the thermal fuse. It is the same as on the brewing boiler. As I do not own Minima you will be better off with someone in the know.

A great machine and you will sort it out in no time.


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## DavecUK (Aug 6, 2013)

One arrow to the thermal sensor, another to what looks like the connector. Trace the wires down to the Gicar box and check you don't have a loose wire, check the connector...If that's all OK, and it's still overheating. Then disconnect the connector and remove the thermal probe from the boiler. If you have a 4 year warranty, *contact Bella Barista before doing any of this, in case they don't want you to touch it.* Replacing the probe will most likely solve the problem. If threadlocker has been used, support the boiler, if you can't, you can damage things trying to torque it off. You may even have to use an impact wrench or sharp raps on the spanner to shock it loose without putting undue strain on the boiler mounts and pipework.

Removal of the outer case is ideal to do this....When refitting clean all threadlocker off and use PTFE tape...you don't have to tighten it right down with PTFE tape, just most of the way. You might need 5-7 turns and it should be reasonable tight all the way in. This way if you ever have to remove it again, it will come out very easily. You may be lucky, in the early ones they used PTFE on the thermal probes...if you can see PTFE tape on the fitting, you will probably be able to remove it from the top without removing side panels or any hassle.


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## El carajillo (Mar 16, 2013)

DavecUK said:


> View attachment 55230
> 
> 
> One arrow to the thermal sensor, another to what looks like the connector. Trace the wires down to the Gicar box and check you don't have a loose wire, check the connector...If that's all OK, and it's still overheating. Then disconnect the connector and remove the thermal probe from the boiler. If you have a 4 year warranty, *contact Bella Barista before doing any of this, in case they don't want you to touch it.* Replacing the probe will most likely solve the problem. If threadlocker has been used, support the boiler, if you can't, you can damage things trying to torque it off. You may even have to use an impact wrench or sharp raps on the spanner to shock it loose without putting undue strain on the boiler mounts and pipework.
> ...


 Having recently renewed the temp probe on my Verona ( same probe) the black band is sleeving on the probe wire.

My probe was threadlocked with a copper sealing washer. 17 mm spanner and lots of light taps with small hammer. It was tight.


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## DavecUK (Aug 6, 2013)

There is a connector some way down the probe wire on the Minima...I'm fairly sure of it.


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## brewd (Jun 24, 2019)

DavecUK said:


> View attachment 55230
> 
> 
> One arrow to the thermal sensor, another to what looks like the connector. Trace the wires down to the Gicar box and check you don't have a loose wire, check the connector...If that's all OK, and it's still overheating. Then disconnect the connector and remove the thermal probe from the boiler. If you have a 4 year warranty, *contact Bella Barista before doing any of this, in case they don't want you to touch it.* Replacing the probe will most likely solve the problem. If threadlocker has been used, support the boiler, if you can't, you can damage things trying to torque it off. You may even have to use an impact wrench or sharp raps on the spanner to shock it loose without putting undue strain on the boiler mounts and pipework.
> ...


 Thanks for the response. It does indeed have a connector on the temperature probe wire, however, it appears solid and I was actually unable to detach it, same for the main boiler probe.

I couldn't see any PFTE tape on the fitting, so I assume it's using threadlocker.

The BB engineer was out of the office this afternoon, but I was told I'd hear back by Monday end of day, so I will hold tight until then.

Do you know if the replacement PTFE I use has to be temperature resistant or can I go ahead and use standard plumber's PTFE?

Many thanks for your help with this Dave.


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## DavecUK (Aug 6, 2013)

brewd said:


> Thanks for the response. It does indeed have a connector on the temperature probe wire, however, it appears solid and I was actually unable to detach it, same for the main boiler probe.
> 
> I couldn't see any PFTE tape on the fitting, so I assume it's using threadlocker.
> 
> ...


 Just common o garden PTFE is fine.

The connector has a certain name, if you get a close up of it...because I'm sure it comes apart. I'm hoping a probe replacement sorts it all out.

What's interesting is that it seems many makes of machines all use the same probes, possibly from different Italian factories and there does seem to be less reliability than I would expect. That said, I have never had a probe fail on any of my machines. My suspicion is perhaps some are not potted in well...but I would be guessing? It's certainly a not how much you pay thing...they are all pretty much of a muchness on price.


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## brewd (Jun 24, 2019)

@DavecUKQuick update on this. BB sent me a new temp sensor.

Last email I got was the following:

Does not look horrendous but clearly some bigger particles when removing temp sensor photograph existing unit and send through if any calcium on it then remove boiler level probe and manually scrub clean any scale deposits on this also.

I asked which the "builder level probe" is on Wed am but, unfortunately, did not hear anything back. Was hoping to get this sorted over the weekend so was hoping you could point me in the right direction. Is the level probe the one with the 2 red wires going into it, with one labelled T.V.?









Some images of the removed temp sensor below. Looks like some calcium build up - think it could do with a descale?

























Many thanks in advance


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## DavecUK (Aug 6, 2013)

level probe (green arrow)









You can clean the probe, but don't think scale is the problem, there was a batch of probes and a few went bad back in the day. It does depend on the water as it doesn't scale as fast at the top as down in the boiler.


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## brewd (Jun 24, 2019)

DavecUK said:


> level probe (green arrow)
> 
> 
> View attachment 55717
> ...


 Thanks for the speedy response. In that case, will swap out the temp sensor and see if that does the trick first.

Would you recommend a descale of both boilers while I've got the cover off?


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## Rob1 (Apr 9, 2015)

I know Volvic will scale, not sure about Waitrose essential. If you've got a TDS meter you could check the water in the service boiler to see how far off you are from the tank. Could be worth a light descale if you think it is bad.


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## brewd (Jun 24, 2019)

Ok, so swapped out the temp sensor and it appears all is well. Had the boiler on a couple of hours and it stayed at temp with no funny business.

Removing the old sensor was easy enough with a few taps on the wrench and some elbow grease.

Will keep an eye on it over the next few days to be sure all is well but might give it a light descale in the near future.

Does anyone know if its possible to get replacement screws for the minima? We had one casualty getting the case back on.


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## DavecUK (Aug 6, 2013)

Just standard stainless hex bolts M3 or M4, write to ACS, I'm sure they will tell you.


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## brewd (Jun 24, 2019)

ACS were really helpful (emailed back at 6am on Saturday morning!) The screw is a standard M4 with hexagonal socket head.

Heard back from BB, looks like a descale is necessary:



> The boiler level probe is mounted vertically in top of boiler with single wire connection and two nuts holding the steel rod in place, the rod is best removed by undoing the larger nut only take out rod and thoroughly de scale.
> 
> Your machine has almost certainly failed due to calcium build up and requires a full de scale instructions available under our citric acid de scaling product on web site.
> 
> Once de scaled either change filtration or additional filtration different water source in future to prevent re occurrence.


 Any thoughts on whether it's worth switching from Volvic going forward? I remember finding a guide on the science behind why Volvic is the best choice in terms of taste vs scaling-potential. I don't mind a light annual descale but if its going to be problematic I will look into finding another type of water to use.

Thanks


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## MediumRoastSteam (Jul 7, 2015)

@brewd Even though Volvic is "OK" - it will scale on the long run, and, if you never replenish the water in the service boiler via the water tap from time to time, the concentration will keep building up. How long have you had the machine for? Presumably over 2 years?

Going forwards... Osmio Zero with remineralisation cartridge, RO water. or, like me, distilled water, with my own remineralisation of 100mg/L of Sodium Bicarbonate (Baking *Soda*) to act as a buffer.


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## Rob1 (Apr 9, 2015)

Not sure what 'science' that would be....talking about taste is always going to be questionable. Alkalinity is on the high side imo if considering taste and it will scale...I used it for years but I felt like it wasn't great either for not scaling or taste, there just wasn't anything better. You can mix Volvic and Ashbeck to bring the alkalinity (and maybe hardness too?) down which will decrease scaling potential, maybe to the point it won't scale. Service boilers make managing water with hardness a nightmare though. Nobody wants to be using water just below the point it will form scale and have to flush 1.5-2 litres of water out of the boiler every few days to stop scale forming as you essentially perform distillation when steaming. I also avoid chloride like the plague and both Volvic and Ashbeck are over 10mg/l for it, this will obviously increase in a service boiler too.


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## brewd (Jun 24, 2019)

MediumRoastSteam said:


> @brewd Even though Volvic is "OK" - it will scale on the long run, and, if you never replenish the water in the service boiler via the water tap from time to time, the concentration will keep building up. How long have you had the machine for? Presumably over 2 years?
> 
> Going forwards... Osmio Zero with remineralisation cartridge, RO water. or, like me, distilled water, with my own remineralisation of 100mg/L of Sodium Bicarbonate (Baking *Soda*) to act as a buffer.


 Oh interesting. So it's beneficial to chuck some tap water in from time to time, even in area like London with hard water?

I've had the machine since June 2019 so coming up on 2 years.


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## Rob1 (Apr 9, 2015)

brewd said:


> Oh interesting. So it's beneficial to chuck some tap water in from time to time, even in area like London with hard water?
> 
> I've had the machine since June 2019 so coming up on 2 years.


 No....

Oh I see you've misinterpreted "water tap" he means hot water tap from the service boiler. As in drain the boiler using the hot water tap and let it refill from the reservoir.


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## brewd (Jun 24, 2019)

Rob1 said:


> No....


 Right, I think I've just realised what @MediumRoastSteamwas implying. Emptying the service boiler via the hot water tap from time to time is recommended.


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## MediumRoastSteam (Jul 7, 2015)

brewd said:


> Right, I think I've just realised what @MediumRoastSteamwas implying. Emptying the service boiler via the hot water tap from time to time is recommended.


 That's it! Sorry for the confusion.


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