After 1.5 years of using 150ppm hardness water (Arlington VA) filtered through a 3 week (max life) Brita filter (drops it to 50 ppm) I decided it was time to descale the boiler and HX on my Andreja Premium. The following are some key points from the experience FWIW....(this is from memory so my recall may not be 100% but it should be good enough). The descaling was done at home because the only available alterative for descaling was shipping the machine back to the vendor for service and that didn't seem like a practical option.
I used the updated draft instructions from J. Schulman (found on the Home-barista site) that call for citric acid. Although available on the net from various strange sources that I didn't really want to give my CC# to, I finally found a somewhat local brew supply store that had the goods (pure food grade citric acid is really cheap stuff and nobody except bath fizz and health kooks make any money on the stuff so its not real easy to locate. In general it is used by bread makers, beer/wine makers, health food/vitamin shops (hey it sounds scientific AND its harmless to eat so it makes a great phony health remedy!) and soap makers and it is also sold as "sour salt" for baking.
Instructions were straighforward and easy to follow. I purchased a few alligator clips from Radio Shack and created wire that I could clip to the autofill sensor and an available pipe coming off the boiler to ground (i.e., shuts off pump when grounded as if boiler was full...i.e., disables autofill, pump overfills when normal connection is removed from sensor, and, of course, autofill normal when normal connection is in place). That all worked fine and as noted in the instructions.
Descaling the boiler involved filling it with the acid solution, let it heat so the boiler valve seals (sorry don't know the exact name but its the valve at the top of the boiler that goes pffffssst on startup as the boiler gets rolling and builds pressure.....this valve needs to be under steam pressure to stay closed...that is a key point that must be remembered when descaling by this process), then overfill until acid solution comes out of steam wand, then shut off, reconnect the ground wire to disable autofill and turn on and let the machine go for a few hours and then flush with fresh. Of course, see the exact instructions for the exact details (don't rely on this, please!).
Now the challenge came when trying to purge the acid solution from the boiler through the water wand. Of course, when hot, you shut the machine off and can purge much of the water using the pressure in the boiler, but subsequent refills for rinsing are tricky becuase you can only run the pump for 25 seconds at a time (according to machine instructions) and then have to wait 5 minutes between these fills to give the pump a rest. In my case, I think it was after the first 5 minute wait, the next refill was supposed to be an autofill to the top and out the steam wand but I heard the pressure valve at the top of the boiler collapse (due to cooling and loss of pressure) requiring me to avoid the overfill, wait for machine to heat up fully and close the valve, then restart the boiler rinsing/overfilling process again. Since you have to do a number of rinses, and the rinsing process requires different wiring settings (ground, no ground, connected etc) this obviously takes time, but you want to be sure to keep an eye on that valve because if it opens while you are over filling then your acid solution will douse the inside of the machine w/ all the wires (wires and acid not good combo). After what seemed like most of the afternoon all the flushing was done (total time probably was 4 to 6 hours for the job...of course mine took longer because of what I discuss in #5). I'm sure its possible to drain the boiler from the bottom tap but I didn't want to go there due to lack of info.
Note that chrome does not like citric acid. Following my 3rd boiler flush with acid when descaling the HX (just flushing acid from the water tank out the group w/ autofill off if I recall correctly) I got a cup full of "chrome snowflake" water coming out of the machine. Having heard others discuss this before I immediately knew that the acid was removing the chrome from inside the group (aparently normal). So I located an enormous pipe wrench and some leather to protect the chrome and removed the mushroom (large bolt on top of E61 group).
After the descale treatment the mushroom was almost completely devoid of chrome (very effective!) and so I brushed off what I could and rinsed out the open E61 will cups of tap water (its just a tube so the flakes flushed right through) and removed the group gasket to get whatever chrome was stranded there, and also removed the small E61 bolt on top of the big bolt to clean the small screen of flakes. On the shower screen/gasket it looked like the acid took the plating off the coarse screen part of the setup so it looks like removing the gasket before an HX descale would be a good pre-emptive move. Leaving the gasket/screen off for the moment, I then went through the tedius process of installing the mushroom, turning machine on, flushing the HX of flakes, removing the mushroom, flushing the E61 shell/hole w/ more tap water, assembling, flush HX...etc repeat until all flakes are gone. Then once cleaned of flakes, I installed a new gasket/screen (done before but this time it was a *major* hassle...perhaps cause the machine was hot).
There were still a few tiny microscopic flakes in the cup water when finished but after about 4 days of normal use everything went back to normal (i.e., do not see any more chrome flakes in the brew water).
Note that I had removed the mushroom it a week prior just to check the level of scale and was surprized at the time to find only little patches here and there only where the chrome had already started to come off...very small mm size patches...aparently the scale attaches to copper more readily than chrome. Note that after 1.5 years of using the Brita filter 3 week changeout approach the scale was not real noticeable in the group (not the like the picture of D. Kehn's mushroom w/ the big pile on it). Thus, at least for my 150ppm total hardness w/ 17ppm alkalinity the brita seems to do a reasonabl job but I did the descale anyway since I couldn't see what it looked like in the boiler. Since I had not previously descaled and only back flushed every month or two w/ cafiza it appears the chrome flakes off of the mushroom slowly regardless of whether you descale but descaling does certainly expedite the process.
Bottom line, if you are planning on descaling an E61, its probably better to take the mushroom out and de-chrome it beforehand by carefully soaking the stem in citric acid (while protecting the outer bolt chrome) and perhaps avoid most of the above iterations. If you have access to a wire wheel brush/grinder then that would probably do a great job at cleaning up the mushroom as well.
Machine has been working great for a month or so post descaling and there seem to be no lingering ill effects so far. Of course, YMMV and you do any of this at your own risk.
wow. great writeup. i dont understand why the insides of the machine and PFs have to be chromed, esp if they present these problems and can present a metallic taste into the cup. did you have to change the screen a 2nd time after all the flakes were gone? id imagine some would get stuck up in the group; or do they flush out easily?
my machine is still pretty new, but im hesitant to do this. id rather take the whole thing apart for some reason. lol
Yikes! It sounds like you are using a pretty strong acid solution for routine dscaling if it is stripping the chrome off the brass of your group head. If you've been using Brita filtered water since the machine was new, I would not expect that you would have a serious scaling problem (or hardly any scaling problem). This is the sort of treatment I would only expect might be needed if a machine had been used for an extended period with very hard water and had extensive scaling that was causing it to malfunction. The white vinegar solution I use for routine maintenance does not remove the chrome from my grouphead (or portafilter or sink fixtures or any other chromed brass).
Some good questions were asked, I'll try to answer together below:
-- re: why is there chome on inside of E61 and is it just Quickmill?
While I'm not an expert on the chroming process, it is a form of electroplating where parts are immersed in a chromium solution and an electrical current plates the material onto the parts from the solution. While I'm sure its possible to "mask" the parts to avoid plating certain areas, I'm guessing this adds cost and because of the E61 shape it may be difficult to do this while maintaining the durability and appearance of plating. This should be a similar issue for any chromed E61 and not just QM, but I will admit to knowing little about where all the E61's come from (who makes them) and whether there is one or more manufacturers out there. Why they plate the mushroom (not sure if its chrome, could be nickel or other) is news to me but it may be to limit scale buildup. BTW, I think I said the mushroom was copper and its probably brass. I will add that I really like the chrome finish on the E61 and it makes it real easy to clean (so I'm glad its chromed). The internal chrome will come off one way or another eventually so this process just expedites it (rather dramatically).
-- re: changing the screen a 2nd time
I kept the group gasket/screen off while flushing and didn't bother to replace again. There could be a few flakes in there but any residual would likely be backflushed out so I'm guessing its clean. If no flakes are coming out in the cup then there is no problem. I'm not sure what the screen innards are plated with but it looks like chrome and while I didn't dissassemble mine, if I look at the botttom side in the light the backing on the other side of the screen (i.e. that metal plate w/ holes) appears to have lost a fair amount of the plating in patches.
-- re: metallic taste
I don't think chrome imparts any taste. Usually metal taste is from iron.
-- re: strength of acid
I used the recommended dilution in Schulman's draft instructions and I believe they were consistent with other's recommendations. An excerpt from the instructions follows:
"The descaling solution of choice is 1.5 to 2 table spoons of citric acid powder per liter/quart of water. It is at proper concentration if you see a light blue/green tinge in the flushed water when descaling.
I ended up using 2 tablespoons/quart but I would agree that it seemed a bit strong in practice and next time I would consider using 1. The mixture used also took the chrome off the inside of my portafilter only in the center "ring" where it thins out and at the upper portion of the downspout. Keep in mind that all the plating that dissolved was fairly thin so I'm not sure this is that surprising. I know professionals use a less or non corrosive descalant but its hazardous material aparently and cannot be shipped like regular consumer goods.
-- re: why bother?
Well...the brita system isn't perfect and our tap water has a fair amount of carbonate (150 ppm). The filtered water goes from 50ppm in the beginning of the filter life to 100ppm after 3 weeks, probably linearly but I didn't bother taking measurements every day to find out but it doesn't stay at 50 for long. I think anything above 50 combined w/ some alkalinity should lead to some buildup. There is also carbonate film on my boiller pressure valve from boiler water bubbling up at startup every morning... which is an indication that some carbonate is being left behind in the boiler. Thus, I figure I would do this about every 1.5 years to keep the boiler happy. I think with this type of machine (i.e., "prosumer") one has to expect to do some regular maintenance every now and then and descaling is part of that.
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