Anyway to clean HX tube Mara X? Water is tasting a bit metallic.

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jlafont
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#1: Post by jlafont »

Hello,

I recently ran a descale at the end of last year and was experiencing some other issues with my Mara X (2020). Thankfully I've sorted out the overheating issues, however after the descale I've noticed water from the boiler and grouphead was tasting metally.

I flushed the boiler with distilled water (I read on here that some folks do that). That seemed to help the boiler quite a bit. Water is tasting better there. However my water that comes out the grouphead still has a metallic taste. I'm not sure if it was the descaler or if it's another source.

Does any one have experience with this? Are there some areas I should be looking at specifically to clean.

I was wondering if there was a way to clean the HX tube since that's where the grouphead water is coming from, right?

Any advice would be appreciated!

Nunas
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#2: Post by Nunas »

jlafont wrote:<snips> I've noticed water from the boiler and grouphead was tasting metally. I flushed the boiler with distilled water. That seemed to help the boiler quite a bit. Water is tasting better there. However my water that comes out the grouphead still has a metallic taste. I'm not sure if it was the descaler or if it's another source. Does any one have experience with this? Are there some areas I should be looking at specifically to clean. I was wondering if there was a way to clean the HX tube since that's where the grouphead water is coming from, right?
Yes, the brew water comes directly from the reservoir via the HX tube to the group head. When you descaled, if you ran some descaler into the HX tube and let it sit for a bit, then it's descaled too. IE: no boiler water enters the HX. Normally, off taste after descaling is removed by flushing with clear water. You don't need distilled water for this. I'd flush some more water through the brew circuit. If that does not do the trick, then I'd live with it for a while; the normal brewing process flushes the HX, since only pure water goes through the heat exchanger. I know of no way to clean the inside of the HX tube beyond chemicals, nor should it be needed.

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BaristaBoy E61
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#3: Post by BaristaBoy E61 »

Perhaps another round of complete descaling might be in order.
What was the colour of the flushed water when descaling?
Had you used the right concentration of descaling fluid?
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

jlafont (original poster)
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#4: Post by jlafont (original poster) replying to BaristaBoy E61 »

The descale was ran in October 2023.

One by my dealer and then once I received the machine another one was ran, since I was still having heating issues (which we suspected it was scale). Ultimately, it wasn't scale causing the issue, although it appear there was some present in the machine.

When I ran the descale (#2), I guess the water had a slight green hue. Here is a photo of the water out the boiler. I also added photos of the mushroom (before descale #2).

I'd like to thing the HX tube was flushed properly. I'm learning a lot about how these machines actually work, outside from pulling a great shot. The water in my boiler actually taste fairly okay, but the group head water taste metallic to me. I'm about to try the rpvalis water formula to see if that 1. Prevents scale, 2. Improves the taste that I'm currently experiencing.


I'm not sure if grouphead water always taste a bit odd.




jlafont (original poster)
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#5: Post by jlafont (original poster) »

Nunas wrote:Yes, the brew water comes directly from the reservoir via the HX tube to the group head. When you descaled, if you ran some descaler into the HX tube and let it sit for a bit, then it's descaled too. IE: no boiler water enters the HX. Normally, off taste after descaling is removed by flushing with clear water. You don't need distilled water for this. I'd flush some more water through the brew circuit. If that does not do the trick, then I'd live with it for a while; the normal brewing process flushes the HX, since only pure water goes through the heat exchanger. I know of no way to clean the inside of the HX tube beyond chemicals, nor should it be needed.
It doesn't seem to be affecting the taste of my coffee. I guess it concerns me since I wonder if there's a bigger issues going on internally.

Nunas
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#6: Post by Nunas replying to jlafont »

Since your machine is producing acceptable espresso, steam and water, I doubt there are bigger issues, or you'd be reporting other symptoms beyond a slight metallic taste.

Your photos don't show a lot of scale. If you read enough threads here on H-B about descaling, you'll find that quite a few folks report that, after descaling, their water had an off taste and sometimes report a greenish or bluish tinge of colour. I'm no metallurgist, but to me, it would seem to indicate that the descaling has removed scale right down to the bare metal, not just in the boiler but also in pipes and fittings. Usually, the machines in question have copper boilers. I'm fairly sure your machine has a stainless steel boiler. So, I can't imagine where the metallic taste or any tint would come from, unless it's the copper pipes and fittings. If so, I'm still betting it will flush out on its own.

For good care of your boiler, be sure to use appropriate water, especially harness; rpvalis water recommendations are a good place to start. Also, dumping a bit of boiler water via the hot water wand after each session, especially if you do a lot of steaming, is a good idea; this keeps the boiler from building up dissolved solids. For example, use a shot of hot water to pre-warm your cups, heat the portafilter basket after rinsing, and to wash your screen pucks if you use them. I'm not a proponent of using hot water from an HX machine for such things as tea or even americanos; I used to have a small, commercial HX machine and I always thought that the water tasted a bit off from it. . Even with my DB, I use a kettle for hot water, but if I need some in a hurry, and the machine is on, I put some water and a thermometer in a foaming jug and steam it up to the temperature I need, depending on the type of tea.

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BaristaBoy E61
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#7: Post by BaristaBoy E61 »

Your machine looks pretty good after the descaling.
What's that Teflon looking insert in the top thermosiphon port?
Looks like it would restrict the water flow and impede proper function affecting group temperature stability.

Can't say I've seen that before.
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

Nunas
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#8: Post by Nunas »

BaristaBoy E61 wrote:<snips> What's that Teflon looking insert in the top thermosiphon port? Looks like it would restrict the water flow and impede proper function affecting group temperature stability.
I was wondering the same thing, but it appears to be stock. My best guess is that it is part of the plumbing mods that the Mara X has to reduce/eliminate the need for aggressive flushing to obtain proper brewing temperature. My old Magister was a "dragon HX", which needed extensive flushing before it would quit breathing stem and fire :wink: :lol: Until the Mara X, I think all HX boxes were dragons.