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To Descale or Not To Descale

Postby AndyH on Mon Jul 23, 2012 12:51 am

After doing research on HB for a grinder upgrade from my beloved Mazzer Mini, I bumped into some of the espresso machine maintenance threads and realized I have neglected the descaling part of routine maintenance for my Izzo Alex (E61 HX single boiler machine).

I have never descaled my Alex, which I purchased new 5 years ago and have been using every day since then for a relatively modest 2 doubles per day (95% straight espresso shots, 5% steam use like cappa etc) plus a few extras on most weekends. Four years ago I did a water hardness measure and found it to be relatively soft at around 35-50 mg/l hardness, so I decided to run the machine off that soft tap water and left the descaling issue alone.

So imagine my terror the other day when I saw examples of scale buildup like this: HX-E61 with lots of scale on the mushroom, how should I descale the rest? or this:
Is there any way to (partially) descale a commercial espresso machine without pulling it apart?

I became worried that I may be heading for a tear down / rebuild project to remove the scale that must have accumulated over 5 years of use.

I was able to find several good descriptions of how to descale the machine:
Jim Schulman's Insanely Long Water FAQ. The title is intimidating but it is broken into sections and very helpful.
Simplified HX Descale (PourOver)
How to Descale a HX Machine Properly

However, before ordering Dezcal or citric acid powder, I wanted to be sure I wasn't going to ruin my machine. I believe that the issue of when/how often to descale an HX machine is not settled. Forum posters and others seem to recommend anywhere between descaling on a monthly basis, to 1-2 times per year, or never (according to Chris Nachtrieb, who sold me my Alex). This quote is from the most recent Alex user's manual at chriscoffee.com:

Chris Coffee Service wrote:Descaling is the process of running a descaling agent such as citric acid through the machine to remove the accumulation of mineral deposits.
- If you are using softened water then it should not be necessary to descale the machine.
- Often times descaling can cause more problems than it solves. It can react to the minerals and foam over ruining electrical components. If the solution is too strong it can cause the chrome plating inside the group to flake off and get in the coffee or if it‟s too weak it can dislodge minerals and cause a blockage. For liability reasons we strongly discourage descaling and will not provide any instructions on the process.

There are also forum posts on HB and elsewhere of strange noises and other problems after descaling, so to me there is not a clear answer on when descaling is recommended for a home user like me.

I needed a way to determine the extent of scaling in my machine.

One way would be to calculate from Jim Schulman's FAQ. Using his formulae I came up with a rough number of ~32 grams of scale buildup over the five years. (10.9 L / month * 49 mg/L scale * 60 months = 32 grams scale). This is five times the recommended level for when to scale -- his recommendation is to descale between 2.5 and 5 grams of scale buildup.

Another way to estimate scale buildup is from erics, who found a proxy for scale accumulation in E61 machines. The idea is to remove the plug at the top of the E61 grouphead and check for scale: Checking an E61 Espresso Machine for Scale. If the plug has significant scale, then it is likely the rest of the HX has scale as well.

So I found a suitable wrench and pulled the plug from my Alex, and this is how it looked:
Image

So, here I am. I estimated 32 grams of scale buildup, but to me the grouphead plug looks fairly clean. So I am not certain about my next move.

Can anyone make a recommendation, to descale or not to descale?
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Postby Peppersass on Mon Jul 23, 2012 2:32 am

Holy Cow. If your plug looks like that after five years, I wouldn't descale -- ever.

Generally speaking, 35-50 ppm of hardness is pretty low, and I wouldn't think you'd need to descale. That said, my recollection is that Jim's Water FAQ says the scaling rate is also dependent on the alkalinity, and you haven't given us that measurement.

Still, the plug is about the cleanest piece of metal from inside an espresso machine boiler that I've ever seen. If it was my machine, I wouldn't dream of descaling.
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Postby erics on Mon Jul 23, 2012 8:35 am

"Ditto" to what Dick G. has said. In addition, to put things in perspective, a brand new US penny weighs 2.50 grams.

A nice link on scale: http://www.me.utexas.edu/~solarlab/solscale/environ.html
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Postby AndyH on Mon Jul 23, 2012 10:11 am

I was leaning against descaling but want to be sure.

I'll count myself as fortunate to have soft water from the tap. The funny thing is, we've never noticed that "soft water feeling" where you can't rinse off the soap.
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Postby Mark08859 on Mon Jul 23, 2012 10:46 am

I once posted a note to Chris' Coffee Service regarding descaling. I got a reply from Chris himself asking me to give him a call. We had a delightful conversation ranging on a number of topics. His bottom line on descaling, however, was that as long as water flow is not affected, one should not descale. hope this helps.
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Postby allon on Mon Jul 23, 2012 11:45 am

AndyH wrote: The funny thing is, we've never noticed that "soft water feeling" where you can't rinse off the soap.


I think that's a softend water feeling, not something one experiences with naturally soft water.
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Postby mitch236 on Mon Jul 23, 2012 12:08 pm

I've had lengthy discussions with the folks at LM and was told exactly what is quoted here:
Mark08859 wrote:I once posted a note to Chris' Coffee Service regarding descaling. I got a reply from Chris himself asking me to give him a call. We had a delightful conversation ranging on a number of topics. His bottom line on descaling, however, was that as long as water flow is not affected, one should not descale. hope this helps.


I was told there are two sides to scale. One is the buildup causing flow problems (which should be addressed) and the other in which scale protects against corrosion.
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Postby AndyH on Mon Jul 23, 2012 9:28 pm

mitch236 wrote:I've had lengthy discussions with the folks at LM and was told exactly what is quoted here:

Mark08859 wrote:I once posted a note to Chris' Coffee Service regarding descaling. I got a reply from Chris himself asking me to give him a call. We had a delightful conversation ranging on a number of topics. His bottom line on descaling, however, was that as long as water flow is not affected, one should not descale. hope this helps.


Thank you for these great insights. It is interesting to me that some of the highly respected people who sell (and service?) espresso machines are essentially recommending against preventive descaling but endorse therapeutic descaling. In other words, as long as there are no symptoms that the espresso machine has, then there is no need to descale to prevent a problem. But it is okay to descale if there is flow limitation or another problem due to the scaling.

I would think that the whole idea of routine maintenance is consistent with a preventive philosophy; to keep a machine running well and avoid developing forseeable problems. I am uncomfortable with a "wait until it breaks / works poorly" approach in general. In particular with respect to descaling, I have an unscientific suspicion that many post-descaling problems might result from a huge catharsis of crud released into the HX and/or boiler after a massive "therapeutic" descaling event.

Anyway, based on the (very helpful!) responses here, even a preventive descale for me is probably 10+ years away, and I will probably catch upgraditis long before then!
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Postby gbastiani on Tue Jul 24, 2012 9:58 pm

I've got a QuickMill Andreja which I've had for only six months which I bought from Chris Coffee. I've got an in tank water softener / filter and the water I get is around 3g of hardness which I check often. Also the filter assembly I got was from C.C so hopefully I'll get as many years of service out of my QM as you got from your Alex
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Postby erics on Tue Jul 24, 2012 10:16 pm

I've got an in tank water softener / filter and the water I get is around 3g of hardness which I check often.

Of interest, of course, would be the quality of the water going into your reservoir and the quality of the water coming out of a cold grouphead.
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