La Marzocco GS3 - steam boiler startup is delayed

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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#1: Post by stefanbc »


I have a Marzocco GS3 and recently the steam boiler is only ready to steam 2 hours after the morning startup. I can make coffee just fine and playing with the steam temperature setting seems to work once the steam boiler has pressure

Any thoughts on why the steam boiler doesn't start asap/within 15 min of starting the machine. Temperature probe and water level probe look fine on the boiler in the back of the machine

Thank you

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Joined: 5 months ago

#2: Post by w111 »

Which heating mode is it set to? Sounds like it could be set to "Half".

Per LM manual:
There are two options in Power saving
• Full - This mode gives full power to both
the coffee boiler and the steam boiler.
On 120V model, in full power mode, a
20 Amp circuit is required.

• Half - In this mode the power is
alternated between the coffee boiler and
the steam boiler (with priority given to
the coffee boiler).

stefanbc (original poster)
Posts: 6
Joined: 2 months ago

#3: Post by stefanbc (original poster) »

Hi, it is not the full half as far as I can tell.

Here is what happed one morning:
- coffee boiler starts warming up
- at around 170F the steam boiler starts and stops at around .3 bar and kind of drops to 0(?)
- coffee boiler warms to 200F
- 30min later the steam boiler starts again gets to .7 and stops
- I make a coffee and steam with .7 which is not ideal, drops to .2
- 45min later boiler warms up starts again and warms up to correct pressure, I like 1bar
- from this point the pressure seems stable and everything works as expected when making more cappuccinos

I am still puzzled why it does it daily more or less the same as described above
Anything else I should check?

stefanbc (original poster)
Posts: 6
Joined: 2 months ago

#4: Post by stefanbc (original poster) »


any chance someone knows why after startup and steaming milk, the steam pressure doesn't recover for a long time.

Thank you

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Team HB
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#5: Post by Jake_G »

My guess is that your solid state relay or your heating element have failed. Both are easy enough to troubleshoot if you have basic tools, and electric meter and lots of common sense. The common sense part is really important, because if you try to troubleshoot a 120V electric system without it, you can end up dead.

(I merged this topic with your original topic to keep the same answers in the same place)
LMWDP #704

stefanbc (original poster)
Posts: 6
Joined: 2 months ago

#6: Post by stefanbc (original poster) »

Looks like it is the vacuum breaker.
If I leave the machine on overnight all is good