Breville 920XL Dual Boiler: Steam very wet; pump running

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by Newton123 »

Problem started with pump running excessively, possibly the water tank was slightly dislodged but not enough to trigger a warning.

What happens now is that steam is about half steam and half water, and the pump runs more than I would expect. Sometimes the pump is running full on, sometimes it's just a fainter hum that doesn't stop until the machine is turned off. I've tried a reset, tried opening the steam valve and letting it cool, tried opening steam descaling valve with machine off. Brewing works fine.

Searching around there is talk of an airlock, and also maybe of a corroded sensor. I haven't descaled in over a year, but the water here is good quality. Machine is pretty heavily used (7,500 shots to date) and is maybe 4 years old.

What next should I be trying? I've ordered some O-rings in case there is a steam leak of some sort, but haven't opened the machine up yet to inspect.

Thanks for any ideas.


Team HB

#2: Post by JRising »

Have you looked at or cleaned the steam boiler's level probes?

Newton123 (original poster)

#3: Post by Newton123 (original poster) »

Haven't yet taken out the probes. Do they just unscrew? Will I need new o-rings for them? If so, these seem to be larger than the other o-rings. Any idea what size?

If the probes are dirty/corroded would I just use descaler to clean them?

Thanks - I'm just a novice at this repair stuff - all I've done to date is replace a solenoid and a dripping steam valve.


#4: Post by pats4eva »

I had a very similar problem recently and I am still uncertain if it is completely fixed. I removed the level probes and cleaned them, but must have cracked some of the sealing ceramic because I couldn't get them to reseal with new orings so had to invest in a new set, which are easy to buy here in Australia - not sure re USA. Even now I am not completely convinced I have fixed the problem, even though definitely no further leaks. About once a week the steam seems to get excessively wet again like the boiler has over filled so I just drain the steam boiler and start again. I have a theory that there is something wrong with the grounding wire or my water is just too soft, but that seems silly. I will be interested in hearing your complete fix hopefully. The probes are removed by using pliers to pull out the metal clips (after machine has cooled and depressurised and been unplugged obviously), then you just gently pull upward after detaching wires. If there is scale they may take some wiggling to remove. Where did you hear about this air lock theory? I would be interested in that.


#5: Post by pats4eva »

In answer to the other questions you will likely need new o-rings, and yes they are a larger size but can't tell you exactly sorry because I bought a pre made set for the bes920. I just washed my probes under running water.


#6: Post by luvmy40 »

I recently had the same problem develop.

I had a steam seal leak and didn't catch it before my steam boiler thermal fuse blew. I replaced the fuse and found several leaks. In the process of replacing the o-rings and reassembling the steam boiler, I cracked one of the water level probe's insulator. I order the probes from Out West Coffee and replaced all three.

The machine seemed fine for a couple days, then the steam boiler fill pump started running non stop. I tried using tap water instead of my rpavlis mix to no avail(my tap water is plenty hard), the pump kept running. I tested for continuity through the probes to the main board and tested for shorts to ground and everything looked good.

I contacted Breville to try to buy a new main board, as my tests indicated that might be the problem. Breville refused to sell me a new board but did offer a free(out of warranty), one time service for my machine. When I got it back, it had the same problem. I called Breville back on it and they said they had replaced some seals and an electrical connector. When I told them it was still doing the same thing, they said they would send me a replacement machine. They did not say "New" machine. I have to send my broken machine back when I get the replacement.

I just read in the BDB, 5 Years + thread about the same problem and the owner thinks he fixed it with a new ULKA pump.

Newton123 (original poster)

#7: Post by Newton123 (original poster) »

The problem turned out to be a corroded solder joint one of the probes - the wire was barely making contact with the probe and might even have come totally disconnected. I used an alligator clip to clip the wire back on, and all is fixed.

What is interesting is that over the last few months the steam quality had been slowly deteriorating. So it wasn't a binary thing - iffy contact somehow produced bad steam.