In a stream of Random Thoughts ..

Musings and rummaging …

On descaling Izzo Alex Duetto

I like coffee. A lot. So much in fact I 12 years ago bought an Espresso machine and grinder. It's been upgrade to an Izzo Alex Duetto. I like it, and I use nearly every day.

So when making coffee cleanliness is paramount, so is maintenance. The biggest drawback for me in regards to the alex, is that it has to be descaled. I run a water filter in front of it to prevent build up of scales, but occassionally it still needs descaling.

I descaled it today. The process is not particularly difficult, but I do tend to forget it. So I thought I would just write it down.

Descaling solution

Dilute approx 40g of citrix acid to 1L of water. Dilute it using hot water because it disolves faster.

Descaling the brew boiler

Descaling without case removal (the most simple method)

This method takes much longer and is possibly not as thorough, but does mean the case does not have to be removed. Ensure your steam boiler does not need any water (unless you are descaling it at the same time), you really don't want the autofill for the steam boiler to come on, otherwise you will taint the water of the steam boiler. The steam boiler should be off and cold NOT cooling down, if it is hot and cooling, if the water is low, there is a good chance it will call for water as it cools further. Switch to the internal tank (if you are not already using it) and place a descaling solution in this tank, approx 40g of citric acid to 1 litre of water. Use a little boiling water to ensure citric acid is fully dissolved and make up to 1 litre with cold water….the solution should be COLD not hot. If using proprietary descalers follow the manufacturers instructions for dilution. The brew boiler should be on and up to temperature.

Operate the brew lever in short bursts (about 5 seconds), with 15 second pauses between each burst. Do about 15 of these short bursts then leave for 20 minutes. The brew boiler should remain on. Empty any excess descaler out of the internal tank and wash out.

Fill the internal tank with fresh water and flushing in slightly longer bursts (about 10 seconds each) with fresh water, wait about 15 seconds between bursts. This is the longest part of the procedure as it will take a long time to ensure all the descaler is out of the brew boiler. If your descaler is pure citric acid, then drawing a little water in a cup and tasting will quickly tell you if any descaler remains. Otherwise checking if it will curdle milk is another way for other descalers.

Descaling by removing case

Turn of the brew boiler element (via the PID), for early model Duettos this is a simple press and hold of the right hand button (oFF shows in the PID display)and the off setting is remembered when the machine is power cycled. Later models with PID control of the steam boiler, both left and right buttons have to be pressed simultaneously (t1 shows in the PID display), the setting is not remembered when the machine is power cycled. For both methods if the machine has just been switched on, wait for the software revision (currently 1.01) to stop showing in the display before pressing the buttons, otherwise you might reset the PID to the factory default settings!.

Your userguide will detail how to turn off the heating elements if the machine was bought from Bella Barista.1

You will need a pair of safety glasses (which should be worn), a large syringe and plastic tubing to fit the syringe. The components should be available from your local pharmacy and DIY store.

  1. put on safety glasses

  2. ensure brew boiler is cold

  3. Unplug machine from mains

  4. remove case

  5. remove T Piece as shown in photo below (click to enlarge)

  6. suck out water from brew boiler (use syringe and plastic tube)

  7. set water to internal tank, fill internal tank with 1.5 litre descaling solution as above

  8. replace T piece, don't over-tighten nuts, just nip them up

  9. switch on machine and ensure heating elements are disabled as soon as software revision has finished displaying on PID

  10. lift brew lever to fill brew boiler and wait until 50ml of descaler runs through group (ensure no leaks at nuts of T piece), if any leakage UNPLUG machine from mains and tighten slightly

  11. enable heating elements and wait until brew boiler reaches pre-set temp, draw 100ml of water through group….then switch machine off and unplug, wait 20 mins

  12. remove T piece, suck out descaler from brew boiler

  13. refill brew boiler with clean water using syringe and then suck out again….repeat this, the refill one last time and replace T piece.

  14. switch on machine and ensure heating elements are disabled as soon as software revision has finished displaying on PID

  15. empty any excess descaler out of the internal tank and wash out.

  16. lift brew lever to ensure brew boiler is full and wait until 50ml of clean water runs through group (ensure no leaks at nuts of T piece), if any leakage UNPLUG machine from mains and tighten slightly

  17. enable heating elements and wait until brew boiler reaches pre-set temp, draw 200ml of water through group….

  18. Run machine against a blind filter and check T piece for leaks….if none, unplug and replace case.

The t-piece can see seen here:

Descaling the steam boiler

  1. With your machine hot, switch off and open hot water tap, drain as much water as you can

  2. Place descaler in tank, move water selector lever to tanked, switch on and refill steam boiler leave to get hot

  3. Switch off and wait for a while for descaler to work, then switch on to reheat steam boiler

  4. Switch off open hot water tap, drain as much liquid descaler as you can, flip lever to plumbed operation

  5. Switch on and allow machine to refill steam boiler with fresh water

  6. switch off and open hot water tap, drain as much water as you can

  7. Repeat step 5 and 6 as necessary till no taint of descaler remains