Is there any way to (partially) descale a commercial espresso machine without pulling it apart?

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hugz

#1: Post by hugz »

In your regular "water reservoir" style machine you can just descale by putting a citric acid mix in the tank. Commercial (or plumbed in) machines don't have that luxury. I want to give my machine a bit of a clean but I don't want to pull it apart and acid dip all the parts.

A thought that I've had is to fill a bucket with citric acid mix, use a flojet pump to bring it up to mains pressure and connect that to the regular machine pump. From there it's just a matter of saturating the internals of the machine with this mix

Thoughts?

edit: I decided to not be useless and do some searching:
Descaling plumbed in commercial espresso machine
Do most plumb-in machines require external pressure?
Rotary pump inlet pressure

Most important edit: In this post Do most plumb-in machines require external pressure?, phreich details his talks with techs at Fluid-o-tech (aka rotoflow) and procon, who both say that their pumps are fine to run out of a bucket under a few simple conditions.

This raises another question for me. The sightglass on my linea shows it as always being half full (thanks to auto-fill). To descale effectively would I need to use an extra strong solution in my bucket or drain the boiler as much as possible? (by running shots with the pump detached?)

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allon

#2: Post by allon »

On my lever machine, I can pull the lever on the (cold) machine, then pump air into the steaming wand with a regulated air compressor to force all the water out of the boiler. Then, after raising the lever, I use a pliable rubber hose that can snugly slip over the steaming wand to siphon a bucket of descaling solution into the boiler (bucket at a higher level than the boiler). Then manual fill to top off with water. Can heat up the solution in the boiler, if desired. Dump the solution with more compressed air.

This doesn't get the pipes leading to the boiler, particularly the autofill solenoid, but it's easy.

Obviously this won't get the HX on an HX machine (my lever is a single boiler dipper)

Edit: when I descaled my Faema C85 last time using a flojet, I destroyed the pump on the espresso machine (i was using the autofill, which uses the pump). The problem was almost certainly that I heated the solution first - a dumb mistake. So if you use a pump, make sure the water isn't hotter than the pump is rated.
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hugz (original poster)

#3: Post by hugz (original poster) »

My original post assumes that a regular espresso pump needs some inlet pressure to work. This is what I've read, but cannot verify. Even perhaps having the bucket above the pump could work (let gravity provide the pressure).

A potential concern would be whether the acid would have any affect on the non-metal components- Eg, I think that the internals of the Linea flowmeter is plastic?

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HB
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#4: Post by HB »

hugz wrote:In your regular "water reservoir" style machine you can just descale by putting a citric acid mix in the tank. Commercial (or plumbed in) machines don't have that luxury.
Actually it's just as easy for commercial espresso machines by tee'ing in a line leading to a bucket of descaler. That is, to descale the brew boiler, just switch the pump inlet from the mains pressure to a bucket of descaler and draw water through the groups. The rotary pump does not need positive pressure.
hugz wrote:The sightglass on my linea shows it as always being half full (thanks to auto-fill). To descale effectively would I need to use an extra strong solution in my bucket or drain the boiler as much as possible?
You could drain it first so the descaler isn't diluted too much. Or, to descale the steam boiler of a La Marzocco, the service manager at Counter Culture Coffee suggested removing one of the top fittings like the overpressure valve (a deep-wall socket wrench like those used for spark plugs works nicely) and dumping a slurry of descaler directly into the boiler. Below are the steps he recommended:
  1. Power off and depressurize the steam boiler by opening both steam wands.
  2. Confirm there's no steam boiler pressure (gauge reads zero, both steam wands are wide open).
  3. Remove the overpressure valve.
  4. Mix descaler (citric acid) into a slurry and use a funnel to dump it into the boiler via the fitting.
  5. Replace the overpressure valve (no teflon tape or thread sealant required); 1/8th turn past finger tight should seal.
  6. To overfill the boiler, you can briefly remove the wire from the steam boiler water level sensor and power on; power off when you see water exiting the steam wand(s) or vacuum breaker (*).
  7. Allow the descaler to do its thing.
  8. Drain the steam boiler via the drain stopcock (on newer models, it's behind a splash shield)
  9. Close drain stopcock.
  10. Refill boiler; repeat previous two steps and this step several times.
I recently descaled the Strada and followed the steps above, except I used a Flojet drawing from a bottle to overfill and refill the steam boiler because my filter system has a slow flow rate. Finally, keep in mind that the above applies to "preventative maintenance" descalings. It won't help cases like this:



Unfortunately lots of owners neglect descaling, so it's a safe bet that a used commercial espresso machine looks like the above (or worse) and a full teardown is required.

(*) Some La Marzocco models have steam boiler sightglasses; if so, stop refilling when the water reaches the top of the glass.
Dan Kehn

hugz (original poster)

#5: Post by hugz (original poster) »

Thanks Dan

I had a moment of clarity and realised how easy it is to get the acid strength right.

1. Buy some pH strips and measure the pH of some liquid with the right quantity of acid.
2. Make up an extra strong batch of acid liquid in a bucket (double strength perhaps)
3. Pull empty shots through the machine and periodically test the pH of the water that comes out. Stop when the pH matches the optimal mix level

I'm going to try this soon and I'll report back