# Steam Boiler Overheating (ACS Minima)



## Justcuz (Nov 23, 2021)

Hi, I have an ACS Minima (US version) and the steam boiler keeps going over the set temperature (125C) and goes all the way up to 165C, causing the steam boiler to start sputtering and steaming from the top of the boiler. I've been in contact with the store and have been sent a new thermoregulator (one of the bolts that go on the top with wires coming out) as they insist that the problem lies with either the PID sensor or the thermoregulator. I haven't replaced the part yet, but reading up on steam boilers and how they work, I'm concerned that the real problem is whatever regulates power to the steam boiler or the control board as the PID does show temperature correctly (or at least I think it does). Setting the machine to brew only mode keeps the steam boiler off, so I am assuming the problem lies with whatever adjusts power to the steam boiler according to the temperature being read on the display. How would I troubleshoot/fix this issue? Thanks!


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## Rob1 (Apr 9, 2015)

The PID is the thing that regulates power. @DavecUK will have some suggestions.


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## El carajillo (Mar 16, 2013)

I think the supplier is probably correct. The 'bolt' is actually a temperature sensor, this passes information to the PID which uses /processes the information to control the temperature.

Take care when fitting not to bend too sharply the fine wires which come out of the sensor.

You will also need some PTFE tape for the thread when refitting.


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## BlackCatCoffee (Apr 11, 2017)

Fit the part is the retailer sent before you do anything else would be my advice.


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## DavecUK (Aug 6, 2013)

@Justcuz I think I answered you on Home Barista this morning, your post here is more detailed. Fit the sensor and keep an eye on it. If it continues doing it, the Gicar box may be faulty. The pid unit you see is just a display, intelligence is in the box


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## Justcuz (Nov 23, 2021)

So update time. Did the change and the old thermo sensor was very much burnt out with a lot of black stuff on it. Set the temp to 110C for the steam boiler and watched it like a hawk for an hour and it stayed consistent the entire time and I was happy. I then set it to 125C and shut it off. The next day, I turned it on and went about my morning routine, expecting the machine to be okay, but I came back when I heard the familiar sound of steam and saw the temperature reading at 149C and immediately shut off the steam boiler and set it to 110C. After the temperature dropped to 125C, I turned on the steam boiler again to see if the steam boiler would kick on and go any higher and kept going down to 110C


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## Justcuz (Nov 23, 2021)

Another update. Turned on the machine (steam boiler set to 120C) and the machine went past it up to 130C. I quickly set the steam boiler to 115C to see if I could get the machine to stop overheating that way, but it kept going to 135C before I shut it off and turned it back on immediately. After I "reset" the machine, temperatures started to drop, but veeeery slowly. Since this behavior was replicated yesterday, it would seem the machine has no issue with regulating temps from a "hot" start, but a "cold" start causes the issue.


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## HVL87 (Dec 17, 2019)

@Justcuz Much of the community has moved to:

https://*********************.com

If you want to post your updates there.


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