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Thread: How to descale a HX machine properly

  1. #1
    TC
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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
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  2. #2
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    Quote 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.

  3. #3
    Junior Member Squidhead's Avatar
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    Here is an instructional video from the girls at Seattle Coffee Gear:


  4. #4
    Senior Member Yelta's Avatar
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    Excellent post Chris, writing understandable work instructions is not an easy task, full marks to you for this effort.

  5. #5
    Senior Member Yelta's Avatar
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    Quote 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.
    cafelazio likes this.

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    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?

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    Senior Member Yelta's Avatar
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    Quote 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.

  8. #8
    Junior Member Squidhead's Avatar
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    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.

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    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?

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    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

  11. #11
    Member astr0b0y's Avatar
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    Great set of instructions, thanks Chris. Any chance of something similar for a dual boiler?

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    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.

  13. #13
    Sleep is overrated Thundergod's Avatar
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    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.

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    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

  15. #15
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    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

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    Thanks Chris. I needed to do a descale as a little lack of care with filtration (by 'er indoors) showed up with a bit of scale on the mushroom. But I'm not likely to need to do it again for a while.

  17. #17
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    Quote Originally Posted by Jonathon View Post
    Thanks Chris. I needed to do a descale as a little lack of care with filtration (by 'er indoors) showed up with a bit of scale on the mushroom. But I'm not likely to need to do it again for a while.
    If it looks like this (3+mm thick stalagmites in places), then you need to descale. A few bits here and there makes me inclined to exercise caution. I gave this one an 8/10 and this happened in 3 years.

    Good filtration will keep you to a 1 or 2 in the same period for a descale at intervals of at least a few years.

    yuck.jpg

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    Hmm, maybe I jumped the gun a little. I'd say my mushroom was 70% clear, just spots of scale dotted around on it, after about 18 months using Brita jug filtered water....I need to get around to installing a C150 or similar but as you know, Northcote water is usually fairly soft.

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    How do you get descale broth in the boiler for a plumbed in machine. Mine has an external pump. I believe it needs water pressure to stay primed. Or, is there a special technique for drawing from a bucket?
    Cheers, Greg

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    Great write up, I'll be descaling my machine properly this weekend!

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    Just thought I'd add: at the boiler rinsing stage I hooked up a bike floor pump to the steam wand outlet to provide the pressure to empty the boiler. Way faster and more efficient than waiting for the boiler to heat up and be emptied several times...
    Last edited by Alan1; 13th July 2015 at 09:42 PM. Reason: Typo
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    Probe wire mod

    It's a lot less fiddly disconnecting the boiler probe without taking the machine apart, I descale my VBM Jnr every 8 months this saves a lot of time.
    Attached Images Attached Images

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    Just a warning to people with a Wega Mininova. The hot water has its own heat exchanger and it makes the instructions a bit different from above. You can flush water through the steam boiler (steam wand) and flush both heat exchangers (brew head and hot water).

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    another one for WLL

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    Hi folk, new member here.

    We recently purchased a secondhand Expobar Megacrem 2 group high cup machine. Of course the place that sold it too us told us it was "in great condition" yadda yadda.

    We're getting some white particulate matter coming out of the hot water outlet, so now I'm wondering if I should descale it. Done a little bit of research and I'm figuring I can disconnect the water inline hose from the mains water, make a reservoir out of a bucket and some pipe fittings and flush some descaling agent through it.

    What do I need to be aware of here? Do I need to disconnect a water level probe on the boiler to make sure the descaling agent reaches the top of the boiler? Am I going about this the right way? Should I be doing a more involved dismantling and cleaning if I want to do the job properly?

    I'm confident around 240v electricity, and am a pretty handy fellow. Any help would be greatly appreciated, and if anyone knows where I can get my hands on a service manual for this puppy that would amazing!

    Thanks!

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    Chris

    Why not store bought citric acid? Do you mean the descalers based on citric acid (I think Sunbeam uses that) - or the citric acid powder you can buy in supermarkets around the spices section? I have used the powder to descale kettles and it seems to work well without leaving much taste.

    I have quickly searched the forum without seeing other people saying why it would be bad for an HX machine.

  27. #27
    Mal Dimal's Avatar
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    G'day mate....

    Yes, Citric Acid does work to a point.
    It also leaches tiny amounts of copper from the brass (and copper pipes) in situ, when chlorinated water is used (tap water) which leaves the peculiar pinkish copper appearance afterwards. Only atomic levels of copper is displaced and not really a concern.
    While not a problem in itself, there are better products around that do a more efficacious job on the scale deposits and avoid the situation of loosening chunks of scale that may end up in other parts of the hydraulic circuit causing future problems and much heartache...

    Mal.

  28. #28
    Senior Member trentski's Avatar
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    What Mal said. Mainly that the citric acid tends to dislodge chunks of dcal that the cause problems by blocking things.

    Maybe the reaction with the copper causes that behaviour I don't know, but that is less of an issue with commercial purpose developed descalers.

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