Filling the brew boiler of La Marzocco GS/3

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redhood
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#1: Post by redhood »

Hi,

I just registered to this forum, but have been reading lots of posts in the last years. Great source of information, thanks a lot!
I recently received a new GS/3 and have a question regarding filling the brew boiler: From what I understand, the brew boiler is filled during initial set up when the steam boiler is filled, because pump pressure is always applied to the brew boiler as soon as the pump runs. But from the drawings in the parts catalogue of La Marzocco, I can not find any level probe in the brew boiler, so I assume the safety for the heating element fully relies on the first filling caused by the low water level in the steam boiler. What would then happen, if only the brew boiler is emptied for exchanging water, but not the steam boiler, and the machine is switched on with an empty brew boiler? Is there any risk to burn the heating element?

Btw, it seems I got a quite new model (Date 07/15) with some changes, e.g. the power button has changed to the middle, which does not make much sense to me. Unfortunately, the manual delivered with the machine is still the one for the old key layout. Is this version of the GS/3 already known here?



Chris

redhood (original poster)
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#2: Post by redhood (original poster) »

Maybe I should clarify I am only referring to using the integrated water reservoir, not plumbed in operation.

Also, does the machine check in any way if the first filling was successful before actually engaging the heating element, e.g. in case there is leak or a clogged pipe?

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spearfish25
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#3: Post by spearfish25 »

Can you just run some water through the group as a flush? I'd assume your boiler is full once you have water flowing out.
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Compass Coffee
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#4: Post by Compass Coffee »

Water isn't drawn from the brew boiler pulling a shot but rather pumped into and through. It is always full.
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Peppersass
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#5: Post by Peppersass »

redhood wrote:... I assume the safety for the heating element fully relies on the first filling caused by the low water level in the steam boiler. What would then happen, if only the brew boiler is emptied for exchanging water, but not the steam boiler, and the machine is switched on with an empty brew boiler? Is there any risk to burn the heating element?
Excellent question -- and one I never thought to ask!

In the six years I've owned my GS/3, I've never watched the heating element icons in the display while the brew boiler was filling. So I can't answer your question until the next time I drain my brew boiler and refill it!

Of course, you can try the experiment yourself.

If Bill Crossland sees this post he can answer the question.
redhood wrote:Btw, it seems I got a quite new model (Date 07/15) with some changes, e.g. the power button has changed to the middle, which does not make much sense to me. Unfortunately, the manual delivered with the machine is still the one for the old key layout. Is this version of the GS/3 already known here?
I would guess they moved the power button for safety reasons. On older machines, if you happen to let up on the Fn button as you hit the power (hot water) button, and the hot water wand is positioned over the drip tray, the hot water will turn on and could scald your hand. This has happened to me countless times. With the power button in the middle, water might drip out of the group, but it's far enough away from the buttons that you're not likely to have part of your hand or arm under it.

redhood (original poster)
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#6: Post by redhood (original poster) »

Peppersass wrote:Excellent question -- and one I never thought to ask!
Thank you, it just came to my mind during initial set up, when I was not too sure about the order of things to do, and the manual was a bit confusing (and mentioned different steps in English and German). So I wondered if I could actually risk burning the element by doing a mistake during set up.
Peppersass wrote: In the six years I've owned my GS/3, I've never watched the heating element icons in the display while the brew boiler was filling. So I can't answer your question until the next time I drain my brew boiler and refill it!
Do you actively fill the boiler, e.g. by starting a brew cycle, or does the machine somehow notice it's empty and starts filling it? Did you do empty it together with the steam boiler?
Peppersass wrote:If Bill Crossland sees this post he can answer the question.
That was also my hope ;).

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AssafL
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#7: Post by AssafL »

Very smart to move the power button. My guess would be a new firmware version?

As for filling the brew boiler you must wait for water to emerge from the screw on top of the group.

Hence if it plumbed in- no problem. Just leave the power off until water emerges. If it isn't plumbed in - i think there is a chance the heater will run dry. But once the boiler is full the pump will not work if the reservoir is empty.

Btw - I stopped emptying my brew boiler a few years ago. Since it is plumbed in, I just release the expansion balance and wait for about 25 minutes for all the water to be replenished.
I know it is counter instructions - but way easier.
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Peppersass
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#8: Post by Peppersass »

redhood wrote:Do you actively fill the boiler, e.g. by starting a brew cycle, or does the machine somehow notice it's empty and starts filling it? Did you do empty it together with the steam boiler?
There's no fill probe in the brew boiler, so the CPU cannot detect when the boiler needs to be filled.

My machine is plumbed in. To drain it, I turn off the input water, turn off power, allow the machine to cool, open the expansion valve, remove the plastic group cap and remove the bleed screw.

To refill, I return the expansion valve to the same setting it had before I drained the boiler. I do this by screwing it all the way in and the backing it out so the black marks align. I turn screw the bleed screw in maybe one thread so air can escape while the boiler fills. Then I turn on the input water. When water starts coming out of the bleed screw hole, I quickly tighten the bleed screw. Then I turn the machine on. When it reaches operating temperature, I run the group for about 30 seconds and shut it off. This causes the pressure to rise. I then adjust the expansion valve for a maximum of 12 BAR.

I don't empty the boilers often, but when I do it's usually both. But not always. I've drained and refilled them separately.

Way back when I first got the machine, and was running it off the reservoir, I had to run the brew cycle to fill the boiler. As I recall, I had to refill the reservoir one or more times to fill both boilers.

redhood (original poster)
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#9: Post by redhood (original poster) »

Peppersass wrote:There's no fill probe in the brew boiler, so the CPU cannot detect when the boiler needs to be filled.
Ok, that was also my understanding.

If the steam boiler is empty as well, like during initial set up, do you actually have to start a brew cycle to fill both boilers, or is the brew boiler filled together with the steam boiler? At leasts thats my understanding of the manual, when it says:
The water flows inside the
coffee boiler directly when the water
pump is activated. When the GS/3 is
turned on the electronics will activate
the water pump to fill both boilers."

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AssafL
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#10: Post by AssafL »

redhood wrote:Ok, that was also my understanding.

If the steam boiler is empty as well, like during initial set up, do you actually have to start a brew cycle to fill both boilers, or is the brew boiler filled together with the steam boiler? At leasts thats my understanding of the manual, when it says:
The steam boiler will fill automatically based on the two sensors (level sensor and reservoir empty sensor). The pump will run and water will flow to both boilers. If the bleed screw is open, water will flow into both boilers. (If not - Since air is trapped in the brew boiler it will fill a bit until the air pressure inside the brew boiler is around the atmospheric pressure - at that point water will flow to the steam boiler only - BTW - the reason this doesn't happen in the steam boiler is that the vacuum breaker is open during filling).

If the brew boiler fills first (water emerges from the bleed screw) - you are done. If it stops prior to that, you have to press the brew button until water starts emerging from the screw. You will have to replenish the reservoir at least once during the process.
Scraping away (slowly) at the tyranny of biases and dogma.

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