Warning! I am assuming you are qualified to service electrical equipment as you are potentially exposing yourself to voltages that can kill. Please see my article on ELECTRICAL SAFETY. And please abide by all regulations that pertain to electrical safety and appliance servicing for your State or Jurisdiction.

So your BES 920 coffee machine is heating up ok and the display reads 93° and the lights on the buttons all light up, but there is no steam when you lift the steam leaver, just a series of beeps. And you got brave enough to remove the lid and found the steam boiler stone cold. And you found my blog about error logs and checked the error log, and found zip, no errors recorded. And you muttered to yourself, Wow this is strange, what’s going on?. Then you are at the right place on the internet. But the problem is about to get stranger, because you followed my guide on testing the steam boiler fuse and element and they both test ok. (the fuse is the most probable cause so I hope you performed the test correctly) What do we do next?

Ok we are going to check for voltage being applied to the steam boiler, so is the brown wire being energized, see the pictorial below.

Ok we got voltage, so the machine is applying the voltage to the element and its not heating and the fuse is apparently ok. What the hell. So the machine processor is giving the right instruction to the triacs to switch voltage on to the element and heat the boiler but its not heating. This eliminates the NTC sensor and the processor. But before you go ripping the triac board out which on the surface makes no sense anyway, but we can not totally rule it out. There is another pain the arse component in series with the steam boiler element and its famous for acting weird because thats what bi-metal thermostats do. Or thermisto as the Italians call them, which is also a moon orbiting Jupiter. The bimetal thermostat in these breville machines are essentially a piece of metal that changes resistance with heat, that conduct 240 volts to the element, and are strapped to the side of the boiler located right under the water inlet hose that leaks, what could go wrong.

So now that we have isolated the fault to the boiler and it’s associated components, the thermostat and the thermal fuse, both are in series with the element. You are going to have to remove the steam boiler. Normally we get a simple open circuit from these devices when they fail, but occasionally they seek to deceive. Take a few breaths, have a coffee, oh that’s right can’t. And remove the boiler. I’m not gonna tell you how to remove a steam boiler from a Breville machine, it can’t be taught, it just has to be experienced. It is possible to replace the thermostat and the thermal fuse, without removing the boiler. See the photo below. When you try to reconnect the descale valve you will know why I try not to completely remove the steam boiler.

Replacing thermostat without removing the boiler completely.

Anyway, once you have the boiler out or partially removed as above, I suggest you replace both the thermostat and the thermal fuse. Why, because once I had a thermal fuse that played up when voltage was applied but yet it’s resitance tested okay. So unless you want to risk performing this procedure twice, I suggest changing both components while the boiler is out. And make sure the repair is successful. I’ll tell you when you get to work

The photo below, shows a Breville steam boiler and the location of the thermostat and the thermal fuse. I also suggest you meter to the element while you have the boiler removed. In our workshop we will test with a megger tester to ensure the elements not leaking to earth. But that’s another story.

So in summary, you’re likely to be reading this if you have a failed steam boiler. You must go through the process of testing the suspect components and eliminating them. There are multiple components that can be the cause of a cold steam boiler.
I hope this helps, and if you’re still a little confused I have other articles on here that may also assist.

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