La Marzocco Linea Mini - help - scale at group brew head

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
captain_alex1982

#1: Post by captain_alex1982 »

Dear forum, I need your help. After 2 years my LMLM seems to be in service mode. I found water under my maschine and had the feeling that the tank was somehow draining much quicker than before. I did some research here in the forum and found people w/ similar problems replacing the vacuume breaker to solve this. I ordered the parts (together with a new casket) from La Marzocco.

Yet when I opened the machine this morning I found a huge build up of scale (???) where the 3 way solenoid valve attaches to the integrated brew group. I dont know why that is because I always! used filtered water with less than 7ph so definitely no water with lots of scale.

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Anyhow, this is the situation now ...I would love to do the repair myself and felt comfortable to exchange the vacuume breaker. Yet if this becomes much more complicated I might approach a local service-shop here too.

Any recommendations what to do/what to exchange?

Thank you so much for your support already!

Best, Alex

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Jake_G
Team HB

#2: Post by Jake_G »

captain_alex1982 wrote:I dont know why that is because I always! used filtered water with less than 7ph so definitely no water with lots of scale.
Alex,

Filtering your water and ensuring a neutral pH in no way ensures that you water does not have lots of scale.

The buildup on your fittings is proof of dissolved minerals in your water that are precipitating out of solution in your boiler. These dissolved minerals may or may not be in the form of magnesium or calcium ions, but this mess is proof that your water quality needs to be evaluated and improved upon. Posting the results of a comprehensive water test would be very helpful in determining the best path forward for protecting your machine.

The buildup is also evidence of a leak (as is the pool of water under your machine). To address the leak, you will need to remove all of the fittings attached to the integrated brew group that are shown in your pictures, starting with the U-shaped tube, the 3-way brew solenoid and finally both of the adapter fittings that are threaded into the IBG. You'll then need to prepare all of surfaces by cleaning/scraping, treating with vinegar, etc... to ensure you have a good sealing surface to put everything back together with new sealing washers where needed.

Then you're left with the question of how much more of this crud has precipitated out into other internal parts of your machine...

I which you the best of luck in this process. Please keep us posted on how things go.

Cheers!

- Jake

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homeburrero
Team HB

#3: Post by homeburrero »

I agree with Jake that this one looks like it has had scale-prone water.

But FWIW I'll mention that when looking at deposits outside of fittings it is sometimes not a sign of scale but rather evaporated soluble mineral. For example, if you use pure distilled and sodium bicarbonate you will have no scale inside the machine but may see white deposits around a leaking fitting where the water is evaporating, leaving behind a sodium bicarb residue.

PS
The term 'scale' is a little ambiguous. 'Limescale' refers specifically to calcium carbonate, but the shorthand term, scale, is often used for any solid mineral accumulation inside the machine, which may be lots of different things -- often a mix of calcium carbonate, calcium sulfate, magnesium oxide, magnesium carbonate, copper carbonate, etc. Highly soluble compounds like sodium bicarbonate, magnesium sulfide, calcium chloride, etc may add to deposits at a leaking fitting but do not of themselves cause scale inside the machine.
Pat
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captain_alex1982

#4: Post by captain_alex1982 »

Jake_G wrote:Alex,

Filtering your water and ensuring a neutral pH in no way ensures that you water does not have lots of scale.

The buildup on your fittings is proof of dissolved minerals in your water that are precipitating out of solution in your boiler. These dissolved minerals may or may not be in the form of magnesium or calcium ions, but this mess is proof that your water quality needs to be evaluated and improved upon. Posting the results of a comprehensive water test would be very helpful in determining the best path forward for protecting your machine.

Hi Jake, I am living in Germany and people in forums here always recommended a certain brand of Water (Purania) because of its good lime-dh values.

Image

Best, Alex

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homeburrero
Team HB

#5: Post by homeburrero »

captain_alex1982 wrote:I am living in Germany and people in forums here always recommended a certain brand of Water (Purania) because of its good lime-dh values.
Hmmm, given those numbers I'll retract my earlier opinion that it looks like scale-prone water. The deposits are mainly dry residue that you expect to get from long slow leaking and evaporation.

3.71 °dH is about 66 mg/L total hardness as CaCO3
and 57.3 mg/L HCO3 is about 47 mg/L total alkalinity as CaCO3

And looking at the calcium number of 16.5 mg/L you come up with a calcium hardness of only 41 mg/L. That would predict light if any scale in a 125 ℃ steam boiler, provided you aren't concentrating the boiler water by frequent steaming and rarely drawing from the hot water tap.
Pat
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pcrussell50

#6: Post by pcrussell50 »

I wonder if the OPs water can come from a variety of sources whose exact chemistry is variable depending on source? We see that here in North America.

-Peter
LMWDP #553

captain_alex1982

#7: Post by captain_alex1982 »

homeburrero wrote:Hmmm, given those numbers I'll retract my earlier opinion that it looks like scale-prone water. The deposits are mainly dry residue that you expect to get from long slow leaking and evaporation.

3.71 °dH is about 66 mg/L total hardness as CaCO3
and 57.3 mg/L HCO3 is about 47 mg/L total alkalinity as CaCO3

And looking at the calcium number of 16.5 mg/L you come up with a calcium hardness of only 41 mg/L. That would predict light if any scale in a 125 ℃ steam boiler, provided you aren't concentrating the boiler water by frequent steaming and rarely drawing from the hot water tap.

The residue looks almost like a corrosion. Or do you think it could be regular minerals that built up over time, even w/ the water used? I am steaming frequently for lattes but no untypical usage. i barely even touched the hot water tap, shouldnt come from that.

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homeburrero
Team HB

#8: Post by homeburrero »

captain_alex1982 wrote:The residue looks almost like a corrosion. Or do you think it could be regular minerals that built up over time, even w/ the water used?
That bottled water has non-corrosive hardness and alkalinity numbers, but also has a touch of undesirable chloride (25 mg/L) that could contribute to corrosion. Frequent or harsh descaling would be another possible cause of corrosion. But I see no blue-green that is typical of copper/brass corrosion, also see no evidence of pinhole leaks. I think it's simply a slight leak at the fittings. For each liter of that water that slowly leaks past a seal you expect to see 0.1 gram or so of dry residue. Tiny leaks often will seal themself but might resume leaking after a descaling.

captain_alex1982 wrote:I am steaming frequently for lattes but no untypical usage. i barely even touched the hot water tap, shouldnt come from that.
I don't think you caught my point here. When you use the steam wand you are drawing steam out and leaving minerals behind, so the mineral content of the water becomes more concentrated. Many people offset that by occasionally pulling some water out of the water tap and triggering a refill -- that takes some of the concentrated water out of the steam boiler, replacing it with reservoir water.

I think you just need to address those fittings, but I'm no Linea Mini expert and will leave advice about that to others.


P.S.
I just noted that the fittings pictured here are on the brew boiler, not the steam boiler. So my comments about the steam boiler minerals have nothing to do with the minerals seen here. :oops:
Pat
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