Should I descale my machine?

In general, we would strongly advise against descaling your machine unless there is an issue and you know exactly what you are doing. Best practice is to use appropriate filtration to soften your water sufficiently so that scale accumulation is slowed dramatically or eliminated. If you do have to descale, we recommend you use a proprietory descaler such as Clean Machine Activated Descaler. One batch will normally do 2 descales for mild to moderate scale. It’s cheap and effective. For bad scale, use the lot (100g). Do not use Citric acid or supermarket descalers such as CLR. Citric acid can move plaques of scale and these cause problems elsewhere in your machine. CLR is poisonous.
There is danger whenever you descale as you will be working with a powered on machine. The job must be undertaken with extreme care. If you are not competent and don’t hold the appropriate qualifications, leave it for a technician. 240V and water are not happy partners.
To descale a single boiler machine:

  • Empty the tank and fill with descaler at the recommended strength for the brand you are using. Switch the machine on and allow it to come to temperature.
  • Do a boiler prime until you have completely flushed the boiler of water and replaced it with descaler. Soak for 15 minutes. Repeat.
  • Remove the descaler from the tank and fill with fresh water. Repeat the boiler prime multiple times until all descaler has been flushed from the machine.

To descale a Heat Exchanger (HX) or Dual boiler 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 don’t see significant scale, you can stop here.

  • To do this job properly, you will need to force a boiler fill by isolating the boiler probe. If you don’t know how to achieve a boiler fill, don’t descale!
  • 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. Switch off.
  • 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
  • Open the steam wand and force a complete boiler fill until descaler appears out of the wand and then switch the power off then as you want to keep things dry. Close the wand off.
  • NB. With a full boiler, some descaler may leave through the anti vac valve. If required, you could open the steam and hot water wand to allow the excess to escape, and then close them. Where possible, manually close the anti-vac valve until the machine reaches pressure to avoid acid spills. You might 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 you need to force a boiler fill again…
  • Once the descaler is all used, repeat with clean water from the beginning to rinse the boiler- but the 15 minute soaks can be omitted. You will need at least 3 complete boiler flushes.
  • Video guides exist for this process, but we feel it unsafe to link to these as there is a risk of injury in this task for new players. Attempt only if you know what to do.

We charge around 2 hours labour for this job- 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 won’t work for HX machines as the boiler is only ever 1/2 full. It is however fine for single boiler machines. 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.

Shopping Cart
Scroll to Top