# Steam switch on Gaggia Classic keeps on heating to >160c



## londonstuff (Apr 7, 2018)

Hello everyone!

I've spent the last few weeks pulling apart my 2004 Gaggia. I've disassembled the boiler and descaled it, the same with the solenoid and other parts and also used the shell of a non-functioning 2011 unit I was given by a neighbour who had (shock horror!) transferred to a Nespresso. I've bought a stainless steel shower plate, added an improved shower screen, a silicone grouphead seal and today adjusted the OPV so that it gives 10 bars. Essentially this is what I had yesterday before I started putting everything back together and today everything is working pretty close to perfectly.









I've also had an Aubins PID installed for a few years on the old machine and have transferred that over, which wasn't easy. Thanks to Damian Witonski's Youtube video, using the Outy setting in the 89 menu I worked out how to make the PID modify the temperature (before it had only ever shown the temperature rather than adjusted it), so again, that's a great improvement.

I now just have one problem left: when I flick the middle switch to turn the machine to the steam function, the boiler seemingly keeps on heating forever. At 165c I got worried and turned it off. The heating indicator light on the PID also doesn't seem to indicate that it's heating.

As far as I can see, it's either the steam sensor on the boiler, some incorrect wiring or a setting on the PID. (I've set the minimum temperature to 140 and the highest to 150 but also tried min 140 and max 140 without effect). I've attached a short video here as well as a photo of the inside and wonder if anyone can give any suggestions - I would be very grateful.









(My PID isn't normally held on with Fragile tape - it's just there until I can get it working!)






Thank you in advance for your help!

Michael


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## londonstuff (Apr 7, 2018)

Hello all,

I've had another look at the inside of my machine and specifically anything to do with the steam thermostat. It seems on tightly enough but not too tightly. I've swapped it for another OEM steam thermostat which I've got from parts and that has the same effect.

The two connectors coming off the thermostat:



The double-wired one goes to the boiler next to it (the connector by the steam outlet valve) and also to the control panel, essentially number 10 position in the bottom right of the panel (the lower rocker of releasing the hot water switch)


The single-wired one goes into a connector: one of which goes back into the control panel in position 7 (the lower right of the espresso/steam toggle) and the other to the output of the Aubins PID.


























All elements of the PID seem to be wired correctly. The PID settings seem correct, but as I said I've experimented with keeping the maximum and minimum settings either both at 140 or 140 and 150.

The heating indicator on the PID doesn't come on at all when heating to steam temp, and therefore just doesn't seem to stop.

Any help gratefully received!


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## PACMAN (Feb 11, 2021)

Whilst I don't fully understand how all of this works yet - my GC is due inbound any day soon and my PID bits will be (once I've ordered them) but as I understand it, the 'early' PID mods only used one SSR (I can only see one in your machine) and a 'phone charger' to provide some power that I'm not sure where it went. The XMT-7100 PID needs 2 SSRs (one AC and one DC) in order to control the steam - but if you look here,

https://coffeeforums.co.uk/topic/18238-diy-pid-steam-and-brew/page/14/?tab=comments#comment-823028

you'll see that it's not necessarily straight forward.


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## londonstuff (Apr 7, 2018)

Thanks @PACMAN - I hadn't seen that thread so it's helpful to know someone is having the same problems, even if I don't understand much of what's being discussed. I don't really need the steam heated to such a precise temperature - the factory settings are fine, so presumably I could leave the PID for the control of the water but take off the connections for the steam?


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## Rebel (Jan 14, 2020)

Contact Auber, their customer support is very good. IIRC there should only be one wire attached to the steam thermostat.


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## Boomingfast (Jan 23, 2018)

Hi Michael

I had a similar problem with my Classic but fitted with a Mr Shades PID.

My problem was simply that some of the wire insulation to the PID had been slighlty cut by rubbing on the case vents at the back which must have caused a short circuit, I insulated it with tape and now it's fine.

So I would very carefully check the wiring for any insulation cuts. Hope that helps.

Cheers

James


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## londonstuff (Apr 7, 2018)

Rebel said:


> Contact Auber, their customer support is very good. IIRC there should only be one wire attached to the steam thermostat.


 Thanks @Rebel - have done.



Boomingfast said:


> Hi Michael
> 
> I had a similar problem with my Classic but fitted with a Mr Shades PID.
> 
> ...


 Thanks @Boomingfast - I've checked all of the wires carefully but I'll have another look in the morning - I'd thought there could be something in the PID box but it doesn't seem to be the case.

















I've also asked Auberins about the PID settings, from the 0001, 0036 and 0089 settings - if anyone can see anything obviously wrong, please do shout!

It's definitely that the boiler seems to run independently of the PID on the steam setting - the PID doesn't seem to have control of it at all.

*0001*

Su 105

AH1 140

AL1 150

AH2 300 *(the relationship of AH2 and AL2 and how it affects AH1 and AL1 is something I wonder whether is wrong)*

AL2 300

End

*0036*

P 04.1

I 0075

D 018

Souf 0.2

Ot 002

Filt 0

End

*0089*

Inty P100

Outy 2

Hy 0003

Atdu 010

P56 0000

Rd 0

Corf 0

Thanks all!

M


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## 29243 (Feb 8, 2021)

Have you tried drawing out a wiring diagram? It might help spot any mistakes.

With a single SSR setup the SSR should just replace the brew thermostat. When you press the steam switch the SSR is bypassed and the heating is being controlled by the original steam thermostat. This is why it heats independently from what the PID states.

Do you hear the steam thermostat click when it reaches temp. I have a Rancilio Silvia rather than a Gaggia, but they work the same way. When mine hits 140C I can hear the thermostat click off (the temp climbs for a bit more though due to lag). If that's happening and there is still power going to the element then there must be something wrong with the wiring. Another reason why it might not kick in early enough is if you didn't use thermal paste (I.e. the thermostat isn't conducting as much heat from the boiler).

Good luck


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## londonstuff (Apr 7, 2018)

So, the next instalment of the saga but I think I'm now getting close to a resolution.

Auberins sent me the factory settings (why mine were so far out, I have no idea) and adding all of those seems to have stopped the boiler continually heating. However, as said elsewhere on this forum, they said that the PID doesn't affect the steam temp.

On the steam setting, it now goes up to about 163 degrees Celsius when the heating stops (but goes up to a maximum temp of about 170 before starting to drop again) and cycles all the way down to 127c.

From memory before I pulled my machine apart, it went from about 120 to about 140c which I've always assumed to be correct and I assume 170 degrees is way too hot and there's something else wrong - perhaps wiring, or similar.

Does any of this sound familiar to anyone?

Thank you - I hope I'm close to a solution now!

Michael


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## londonstuff (Apr 7, 2018)

So, the final bit of information I can give! I now only have a problem with the steam temperature, the PID keeps the brew temperature at 105 degrees Celsius 

I've changed the steam thermostat for another which doesn't seem to have had a noticeable effect. The steam still seems to cycle from 127 degrees Celsius to 163 degrees Celsius, reaching a peak of about 170 degrees which is clearly too hot. This didn't happen before I pulled the machine apart so after getting confirmation from Auberins that the SSR and the PID device were wired correctly and bringing back the PID settings to factory settings, I can only conclude that it's a wiring issue. (If it helps, the machine also seems to click at various points during the steam heating cycle when it never used to.)

I've attempted to draw the insides as best as I can - it's not an electrical drawing but it should be clear and I've also included a photo of it (I had to take all the cable ties off to see where the wires were going so I'll put those back on at some point.

If anyone who is familiar with the GC internals, especially with a PID installed, I'd be really grateful if you could have a look below. My hunch is a pair of wires could be the wrong way round: perhaps the steam thermostat, the pump or the solenoid or a combination of these.

Thank you very much in advance!

Michael


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## 29243 (Feb 8, 2021)

I'm no gaggia expert, but I've tried to compare it against the wiring diagram and can't see anything that looks wrong.

http://www.shop.partsguru.com/images/Gaggia Classic Main switch 230 Wire connections diagram.jpg

This does confirm that the pid doesn't control steaming. Power runs up the yellow wire bypassing the SSR when the steam switch is pressed.

It seems strange that you see the same with two thermostats.

Hopefully someone with more gaggia experience can spot something.

Good luck


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## 29243 (Feb 8, 2021)

You could also try switching the brew thermostat in for the steam one, drop your pid temp down and hit steam. If it's working correctly it should then fluctuate temp at around 100C


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## londonstuff (Apr 7, 2018)

Hello all. I'm sorry to resurrect this but despite everything that I've tried below, when switching the Gaggia to the steam setting, it still carries on overheating at which point I switch the machine off before the fuse breaks.

I have previously installed an Auberins PID and left it in passive mode for quite a while, which just displayed the temperature on the display, but didn't alter or affect either the brew or the steam temperature at all. For ages it worked fine.

At Christmas I completely disassembled the machine, opened up the boiler and the solenoid for cleaning and put it back together. I couple of parts were mixed and matched between a 2002 and 2011 version. I also changed the brewhead to a stainless steel one, new shower head tray, changed the OPV, etc. Changing the Outy setting in the 0089 menu to 2 rather than 3 put it into 'active' mode and the PID for the first time modified the temperature - it now keeps it constantly at 105 degrees, which is fine. However, changing it to the steam setting consistently makes it overheat, through when heating I can hear a couple of noises like the machine is trying to turn off the heat (which it doesn't).

I've tried literally everything I can think of:



I've verified the settings in the 0001, 0036 and 0089 menu with Auberins


I've checked all the wiring inside the Gaggia with a circuit diagram


I've checked the wiring inside of the PID


With a second, dead, machine that I've got, I've changed all the wiring inside the Gaggia


I've swapped the boiler to no effect


I've checked the integrity of the wires as suggested by @Rebel. There were a couple of very slight cuts to the plastic wiring which I've covered with electrical tape.


I've put the PID back to passive mode (Outy mode 3) and the steam setting still overheats


I've ordered a brand new steam thermostat - no difference


Used thermal paste on the thermostat


Interestingly, putting a brew thermostat where the steam thermostat normally lives means that the temperature cycles between about 92 degrees when the boiler activates and about 130 degrees at the top end, with the control panel lights going on and off as I'd expect. This makes me think that the problem is somehow still related to the steam thermostat or related parts despite me having tried two others.

The only thing that I can possibly think of that's left to check is the integrity of the wiring of the PID by replacing the wiring but I wouldn't have thought that this could affect things too much if the steam setting still acts the same when the PID is inactive.

I could also take out everything and try it as a 'normal' machine, without any PID but then I wouldn't be able to monitor the temperature of the steam and wouldn't want to destroy the fuse.

If anyone can help, I'd be very grateful. I would be very happy to try a @MrShades PID but clearly I don't want to be in a position where I pay £100 for something that gives me the same result if the problem isn't with the PID!

Alternatively, if anyone knows a Gaggia expert near Central London, I'm happy to pay for someone to look at it. At this rate I'm either going to end up with a third Gaggia or a La Marzocco Linea Mini  , which I really don't want to do.

Thank you!

Michael


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## 29243 (Feb 8, 2021)

It sounds like you've been pretty comprehensive Michael. A swing of 92 to 130°C on the brew thermostat sounds a lot to me, is this normal for a Gaggia?

The only thing you haven't looked into is the thermocouple. If this isn't reading reliably it could look like it's not working properly.

Good luck


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## Nightrider_1uk (Apr 26, 2020)

I would put the machine back to original configuration and check wiring is correct using online circuit diagram information. Check that it operates correctly in standard build and sort out ant problems before attempting to modify. Then i'd go for a dual SSR as per mr shades.


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## londonstuff (Apr 7, 2018)

Nightrider_1uk said:


> I would put the machine back to original configuration and check wiring is correct using online circuit diagram information. Check that it operates correctly in standard build and sort out ant problems before attempting to modify. Then i'd go for a dual SSR as per mr shades.


 Thanks @BenH and @Nightrider_1uk. I think I could keep on going forever with various parts. I wouldn't be surprised if it were the thermocouple as the wires are so fragile and need twisting so much. I will try to put everything back to normal and go from there. This feels like falling down a rabbit hole!


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## AndyDClements (Aug 29, 2016)

@ Londons

If I've read this thread correctly, when you have a steam stat the steam temp cycles between approx that steam stat temp and 170, if you have a brew stat in that same place then the machine cycles approx between that brew stat temp and 170. These are all approximates, since those stats have upper and lower points which they switch at and those aren't always precise. If that above is what is happening then in that case, it points to a wiring problem, one where I'd suspect the wiring related to the steam switch to boiler is incorrect.


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## londonstuff (Apr 7, 2018)

So, I put everything back to the original configuration, turned it on and crossed my fingers (and didn't have the fuse on the boiler). It did heat up and after what seemed like an eternity the heating stopped.

sSo, I reconnected the PID and repeated: the boiler kept heating on the steam setting until between 165 and 168 degrees with the residual heat taking it between 170 and 174 degrees - this seems very hot but based on what @AndyDClements says above, it doesn't seem that unusual? The temperature flicked down and started heating again at about 114 degrees, then back up to ~170 degrees.

i don't know whether this maximum temperature is okay or whether it would kill the thermal fuse?

Anyway, I've bitten the dust and ordered a Mr Shades PID. I have a spare machine which I'll put together, put the old PID onto that and perhaps take it to work with the Mahlkonig grinder for a bit. In between running a school, a bit of caffeine will keep me going. 

Any comments on weather the 170 degrees of steam is okay are most welcome, particularly any ways of bringing it down a bit (it used to max out at about 145 degrees).


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## AndyDClements (Aug 29, 2016)

It does sound excessively hot to me, my point was that if I've understood the way its acting, then I believe the PID wiring is incorrect. What would have been interesting would be to know what temperature it got to on original wiring (non-PID), as that would have affirmed the thermal switch as working at the desired temperature. In the end, I think the Mr Shades PID is sure bet, because for all we know the PID itself could be acting incorrectly, ditto the thermal probe, so this way you get a kit with a proven track record.


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## 29243 (Feb 8, 2021)

Personally I don't see how the pid can be the issue, as the steam switch essentially bypasses it.

Using a two output PID with two SSRs would give you control over the steam temp though. Alternatively you could just manually change the set point on your PID when you want to steam, or if the PID has a non-latching alarm output you could use this to cut the heating when you want to steam.


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## AndyDClements (Aug 29, 2016)

When I say "PID wiring incorrect" I mean the wiring configuration when the PID is part of it, not necessarily the wires to / from the PID. I'm using that to differentiate the wiring schemes when with or without a PID.


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## Kmsg90 (May 18, 2021)

Hi, did you figure out the problem with this? I'm having similar issues running just the brew SSR, but when I try using the steam function the temperature climbs until I get EEEE on the PID display


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## robmack (Apr 2, 2021)

I thought the Aubers PID is implementing the Skene single PID design. Is that right? Based on the PID settings posted earlier in this thread, AH1 and AL1 are set to values that indicate this is the case. Below is the original article describing the Skene design:

http://www.skenedesign.com/Silvia/

This design uses both the PID-control and the alarm-control outputs of the PID to steer one SSR to control both brew and steam temperatures respectively. The PID should replace both the brew and steam thermostats, so those two components have to be out of circuit. It's possible that Aubers is recommending keeping the steam thermostat in circuit to act as a failsafe. If that is the case, then the steam thermostat has to be in series with the SSR output and I don't see that in the hand-drawn schematic earlier in this thread.


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