Coffee

8457 readers

3 users here now

☕ - The hot beverage that powers the world!

Coffee gadgets - It's always great to learn about new gadgets. Please share your favorite hardware or full setups. It might inspire newcomers to experiment!

Local businesses - Please promote your local businesses. If you are not the owner of the business you are promoting, kindly ask the owner if it's okay. It would be great if the business has a physical store to include an exterior or interior shot.

founded 2 years ago

MODERATORS

martijn

[email protected]

Uncoated aluminum boiler with brass group head corrosion risk? (lemmy.nowsci.com)

submitted 4 months ago by [email protected] to c/coffee

10 comments fedilink hide all child comments

Hi all,

I've got an uncoated aluminum boiler to replace the flaking one in my Gaggia Classic Pro Evo. Given that aluminum boiler coupled with the brass group head will cause galvanic corrosion, what are my options?

I know I can wait for companies to get chrome plated group heads in stock, but I hear the new (since April) GCP Evos are using the brass group head and the uncoated boiler. How are they pulling that off?

Thanks.

you are viewing a single comment's thread
view the rest of the comments

[–] [email protected] 2 points 4 months ago (1 children)

Isn't there a gasket between grouphead and boiler? I would think a liberal amount of Dow 111 would be what you need. I haven't had one of those apart in years so I can't remember how it goes together exactly.

[–] [email protected] 1 points 4 months ago (2 children)

My concern more stems from electrochemical replacement plating, where the water acts as a transfer agent.

[–] [email protected] 1 points 4 months ago (1 children)

Disclaimer that I have not worked on espresso machines in a bit.

When i did that was usually not a problem, swimming pools filters yes, espresso machines no.

Direct contact could be a problem, though not always. The bolts holding everything together were generally more of an issue, grease helped with that.

The most common issue i saw was caused by water with a high mineral content. But that was scaling more than deposition.

[–] [email protected] 2 points 4 months ago

Thank you. I'm using RPavlis water, so low mineral content.

[–] [email protected] 1 points 4 months ago (1 children)

but that only happens while there is water there, right? so given the limited amount of contact time i think this is not a concern. aluminum has a great capacity for self-passivation too, at least the typical alloys do.

[–] [email protected] 2 points 4 months ago (1 children)

Unless the Classic has changed considerably, it may have idk, the boiler and grouphead are bolted together. So there is always water there, the element would burn out otherwise.

[–] [email protected] 2 points 4 months ago (1 children)

ah ok i mistunderstood what the group head is. if they are both permanently in contact with the water in the boiler then it would depend a lot on the water quality. Water with only a little conductivity (<100µS/cm) would not be a problem for pure aluminium or most alloys, since the aluminium would passivate much quicker than the corrosion could dig into it.
i would assume that a vessel made for boiling water is made of a highly corrosion resistant alloy but i can not know for sure.

[–] [email protected] 1 points 4 months ago

I'm using RPavlis water, so hopefully that works out.