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  • How to descale a HX machine properly

    This post in response to http://coffeesnobs.com.au/YaBB.pl?num=1274612190

    The topic comes up pretty often, so it has been made a sticky item.

    Hi Sammus,

    Its not that tough and Id be thrilled if I saw more machines in good condition rather than being full of barnacles. Its not a job I enjoy. :

    I use Bombora activated descaler and one batch will normally do 2 descales for mild to moderate scale. Its cheap and effective. For bad scale, I use the lot (100g).

    There is danger here as you will be working with a powered on machine and the job must be undertaken with extreme care. If you are not competent and dont hold the appropriate qualifications, leave it for a technician. 240V and water are not happy partners.

    To descale a HX machine:[list][*]First, with the machine switched off and cold, remove the mushroom (large hex nut on top of group) and examine for scale. If you dont see significant scale, you can stop here.[*]Disassemble the machine sufficiently to allow access to the boiler water level probe[*]Switch the machine on and allow it to come to working pressure. Start with a boiler as close to empty as possible. This is achieved by allowing the machine to come to pressure, switching it off and then opening the hot water wand. Boiler pressure will do the rest.[*]Mix the descaler (not store purchased citric acid) according to the instructions[*]Switch the machine on and allow the boiler to fill with descaler and the machine to come to pressure[*]Key bit. Open the steam wand, remove the wire from the boiler probe and allow the machine to drink until descaler appears out of the wand and then replace the boiler probe wire. I often flick the power off then as you want to keep things dry in there. Close the wand off.[*]NB. With a full boiler, some descaler may leave through the anti vac valve. If required, I open the steam wand for a bit and use towels if required to keep things dry.[*]Allow 15 min and then run a little descaler through group and both wands..[*]Repeat every 15 min until all the descaler is gone...Every time the machine drinks again, do the boiler probe bit again...[*]One the descaler is all used, repeat with water from the beginning to rinse the boiler- but the 15 min bit can be omitted. I do this at least 3 times for 3 complete boiler flushes.

    Its a fiddly job, and if youre not confident around electrikery, its not for you. AM has the emote to show you why....

    We charge $150 + parts- because to do the job properly, it takes 2-3 hours.....Other service agents will do it as part of a service and charge pretty much nothing. They just throw some descaler in the tank and rinse the boiler. That approach wont work for HX machines as the boiler is only ever 1/2 full. It is however fine for single boiler machines- like a Silvia for example. Multi boiler machines are treated like a HX machine, but then the brew boiler may need to be flushed more or completely drained to clear it of descaler.

    All of this will probably still be insufficient for really severe scale- the only option being complete disassembly.

    Hope that helps.

    Chris

  • #2
    Originally posted by Talk_Coffee View Post
    This post in response to http://coffeesnobs.com.au/YaBB.pl?num=1274612190

    The topic comes up pretty often, so it has been made a sticky item.

    Hi Sammus,

    Its not that tough and Id be thrilled if I saw more machines in good condition rather than being full of barnacles. Its not a job I enjoy. :

    I use Bombora activated descaler and one batch will normally do 2 descales for mild to moderate scale. Its cheap and effective. For bad scale, I use the lot (100g).

    There is danger here as you will be working with a powered on machine and the job must be undertaken with extreme care. If you are not competent and dont hold the appropriate qualifications, leave it for a technician. 240V and water are not happy partners.

    To descale a HX machine:
    • First, with the machine switched off and cold, remove the mushroom (large hex nut on top of group) and examine for scale. If you dont see significant scale, you can stop here.
    • Disassemble the machine sufficiently to allow access to the boiler water level probe
    • Switch the machine on and allow it to come to working pressure. Start with a boiler as close to empty as possible. This is achieved by allowing the machine to come to pressure, switching it off and then opening the hot water wand. Boiler pressure will do the rest.
    • Mix the descaler (not store purchased citric acid) according to the instructions
    • Switch the machine on and allow the boiler to fill with descaler and the machine to come to pressure
    • Key bit. Open the steam wand, remove the wire from the boiler probe and allow the machine to drink until descaler appears out of the wand and then replace the boiler probe wire. I often flick the power off then as you want to keep things dry in there. Close the wand off.
    • NB. With a full boiler, some descaler may leave through the anti vac valve. If required, I open the steam wand for a bit and use towels if required to keep things dry.
    • Allow 15 min and then run a little descaler through group and both wands..
    • Repeat every 15 min until all the descaler is gone...Every time the machine drinks again, do the boiler probe bit again...
    • One the descaler is all used, repeat with water from the beginning to rinse the boiler- but the 15 min bit can be omitted. I do this at least 3 times for 3 complete boiler flushes.

    Its a fiddly job, and if youre not confident around electrikery, its not for you. AM has the emote to show you why....

    We charge $150 + parts- because to do the job properly, it takes 2-3 hours.....Other service agents will do it as part of a service and charge pretty much nothing. They just throw some descaler in the tank and rinse the boiler. That approach wont work for HX machines as the boiler is only ever 1/2 full. It is however fine for single boiler machines- like a Silvia for example. Multi boiler machines are treated like a HX machine, but then the brew boiler may need to be flushed more or completely drained to clear it of descaler.

    All of this will probably still be insufficient for really severe scale- the only option being complete disassembly.

    Hope that helps.

    Chris
    I'll be attempting this soon, and have tried to make Chris's useful article easier to read.
    I will try to add some photos of the process.

    Kev.

    Comment


    • #3
      Here is an instructional video from the girls at Seattle Coffee Gear:

      Comment


      • #4
        Excellent post Chris, writing understandable work instructions is not an easy task, full marks to you for this effort.

        Comment


        • #5
          Originally posted by Squidhead View Post
          Here is an instructional video from the girls at Seattle Coffee Gear:
          As good as Chris's work instruction was this is the opposite.
          These two gigglers should stick to subject matter they understand.

          Comment


          • #6
            But they're good fun to watch. Admit it, you'd like to know what the cameragirl looks like too right?

            Does the top half of a HX boiler get much scale if the boilers are only ever half full?

            Comment


            • #7
              Originally posted by simonko View Post
              Does the top half of a HX boiler get much scale if the boilers are only ever half full?
              I have no idea, perhaps Chris can enlighten us.

              Comment


              • #8
                There is a video somewhere whereby you roll the Giotto 45 degrees over to one side. This will signal the machine to over fill the boiler and permit the descaling fluid to reach the top area.

                Comment


                • #9
                  Interesting you mention this. It's why I was interested how quickly scale builds up in the upper areas of the boiler and steam wand channels, thinking that steam would have most (all?) of the scale-producing nasties distilled out.

                  Could one get away with an 'open-machine' descale every coupla' years, using the tilt method for the regular descale?

                  Comment


                  • #10
                    Hi All,
                    Thought I'd mention that yesterday I got around to using Chris' correct method to descale a heat exchanger. I was a little worried about what was going to come out, considering that (a) I'd only ever done the basic descale version (where you don't unplug the level-probe); and (b) the last time I descaled I was alarmed at the deepness of the green that came out of the boiler and the milkiness that came out of the group :S
                    Well! I was relieved to see that colour was no where near as deep as it was last time, even though it was the first time cleaning the top half of the boiler.
                    Thanks for the instructions Chris! And if anyone wants a decent instructional using this method...:
                    How to descale a heat exchanger espresso machine - YouTube

                    Oh! And one more thing, I noticed that when a little bit of the descale solution came out of the anti-vac valve, it really made the copper all shiny on the outside again!!

                    -Aaron

                    Comment


                    • #11
                      Great set of instructions, thanks Chris. Any chance of something similar for a dual boiler?

                      Comment


                      • #12
                        Hi everyone,

                        About 2 months ago I bought a 2 year old (heavily used) Bezzera B2009 Compact.
                        Retro 2 Group Compact - Bezzera - Commercial Espresso Machines - Espresso Machines
                        Opened it for the first time about 2 weeks ago and noticed some scale on top of the boiler.

                        My question is if I should descale it using directions mentioned in various threads on this forum. At the place where I bought it, sales person said not to descale it but rather bring it in and they would take it apart and clean the scaled bits one by one.This would obviously cost me more money as it is their goal to have return and repeat customers. To what extent should I listen to this person and how complicated and risky of a job would it be if I decided to do this myself as it is a HX machine and I have never done it with any other machine.

                        Comment


                        • #13
                          As you've admitted to zero experience, it comes down to how handy you are and your confidence.

                          I'm handy but prefer to have my machine professionally serviced.

                          Each to their own.

                          Comment


                          • #14
                            I like to descale my Giotto PP myself, I actually enjoy it, except the flushing the boiler bit at the end, I find that part a bit tedious.

                            So, I was thinking the other day, what if I took off the anti-vac and screwed in a water pipe straight from the tap. Then, with the steam and water wands both open, and the water pressure kept fairly low, I could flush several litres through the boiler in minutes.

                            I've tried to think what could go wrong:

                            It's unfiltered tap water, but once the boiler has been flushed I'd empty it, so the remaining unfiltered water would be minimal.

                            If I pumped too much water in, could it go back out through the OPV and through the Ukla, which might cause a leak? But I can't see this happening with the boiler full of cold water when 1.2 bar of boiling water doesn't cause a 'backflow' problem.

                            Am I missing any other dangers here?

                            Cheers
                            Jonathon

                            Comment


                            • #15
                              Hi Jonathon,

                              We reverse flush them these days- makes the rinse much more thorough. We doctored up some custom fittings to make the flush quick, safe and easy. A little care and you will be fine..

                              Regardless, best not to descale unless there is good reason to do it. Throw acid at copper indefinitely and you end up with a boiler and brittle, dead plumbing

                              Comment

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