Rancilio Silvia doesn't stop heating

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
Omereut

#1: Post by Omereut » Sep 09, 2019, 5:03 am

Hey,
My Silvia has suddenly started to over heat. The light turns off but i can still hear the boiler working and when i press the brew button whole lot of steam comes out.
Cold water enters and everything cools down but still makes this boiling sound when brewing and still over heats.

It's been to the shop 3 times they fixed it and it happens again.
I live in a new house so ground issues don't seem to be the problem here.

The light turns off but i can still here the boiler heating up ( not at the same intensity as before)

Sounds familiar to anyone?

Thanks!

maxiboy66

#2: Post by maxiboy66 » Sep 09, 2019, 7:13 am

Not really familiar with Rancilio this brand machine. I guess you might need to check the pressure switch.

Espresso_Junky

#3: Post by Espresso_Junky » Sep 09, 2019, 7:35 am

FWIW even when the thermostat kicks the element OFF you might still hear it heating a bit longer as it isn't like an instant OFF as residual heat will rise and likely make a bit of noise for a short bit. Regarding the steam, all Silvias AFAIK will have a bit of flash boil/steam from the group right after the element kicks off as they tend to run a bit hot. After you run the pump 2-3 seconds that should fade out.

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Jake_G
Team HB

#4: Post by Jake_G » Sep 09, 2019, 7:49 am

Silvia is a SBDU machine and uses snap thermostats for temperature control. There is no pressure switch.

See How a Silvia Works for a nice color coded layout of the wiring in a Silvia showing all the specific functions.

Here's the one page showing all wiring at a glance:
Image
Image: Silvia wiring schematic, from espressomyespresso.com

The heating indicator lamp is (should be, please verify on your machine) wired in parallel with the element. If the indicator is not illuminated, there should be no voltage present on the element. It is possible that your steam power switch has a resistive short across the switch terminals and is maintaining a constant, but reduced voltage to the element that is high enough to boil the water in the boiler, but low enough to render the indicator dim.

To safely troubleshoot this issue, I would unplug the machine and remove the wire that goes from the brew thermostat to the power switch. Then you can measure resistance across the terminals of the steam switch and see if there is some resistance present when the switch is off. Anything other than an open circuit is suspect.

If the switch measured good, a voltage reading on the element when the problem is present would confirm if this reduced voltage is the cause, but this must be carried out on a machine that is plugged in and powered up. As such, I cannot recommend such measurements without the obligatory warnings that electricity can kill you and you should, under no circumstances do such a thing unless you are a licensed electrician or are otherwise highly aware of the risks and quite confidently capable of carrying out such tasks without becoming dead. Be careful.

In any such case, if the steam switch isn't to blame. The other thing that could cause this would be a resistive short across the terminals of the brew thermostat. This can be safely measured with the machine unplugged, but only when the machine is hot. With the brew thermostat unplugged as before, I would recommend putting the machine in steam mode and waiting until the indicator goes out, and then unplug the machine and measure across the thermostat. Again. Anything other than an open circuit indicates a problem. In this case, be careful not to burn yourself on the absurdly hot boiler.

Post some pictures of your wiring. Some Silvia gurus may be able to spot something amis merely from seeing your machine.

Also, Timmy is correct. The 107C coffee thermostat gives you quite a bit of flash steam after the element kicks off. It is my practice when pulling shots with Silvia to purge this flash steam out of the group prior to locking in the portafilter.

Cheers!

- Jake

Omereut

#5: Post by Omereut » Sep 09, 2019, 8:25 am

Thank you jake and Thank you all for your replies!
I know about the flash boil...this seems more than that.
Actually feels to me like there is a low voltage running through the wiring to make this happen.

If that is the case, after i measure, what is the solution?
I will try to post some pics

Thanks again!

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Jake_G
Team HB

#6: Post by Jake_G » replying to Omereut » Sep 09, 2019, 8:28 am

In the case of the switch, it can likely be repaired if you care. The coffee thermostat is cheap and easy to replace. The switch is likely cheap, too, but is more likely repairable for no cost aside from some time cleaning up the contacts. It may even have a spare set of contacts. Photos of your machine will help.

Cheers!

- Jake

Omereut

#7: Post by Omereut » Sep 09, 2019, 8:35 am

Thanks again Jake i will definitely try to post some pics
Have to find the solution to this!:)

Omereut

#8: Post by Omereut » Sep 09, 2019, 8:46 am

Heres a pic of the wiring...
Image

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Jake_G
Team HB

#9: Post by Jake_G » Sep 09, 2019, 9:12 am

Everything looks ok at a glance.

Unplug the machine and pull the red wire off the brew thermostat.
This will remove power from the element unless the steam switch is the culprit. If you still get boiling with the red wire removed, your steam switch is highly suspect.

The steam switch works by sending power to the grey wire when it is switched on, even if the brew thermostat is open. Unplugging the red wire forces the brew thermostat open and allows us to see if the steam switch is misbehaving.

Cheers!

- Jake

Omereut

#10: Post by Omereut » Sep 09, 2019, 9:24 am

Tried it now and i think it was fine didn't get close to the same boiling point.

What would that mean, that the steam thermostat is fine and the brew isn't?