Breville Dual Boiler - Brew boiler overheating to 225 degrees

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

#1: Post by Diggidy »

Hello All,

I have a Breville DB - the newer 920XL version. I bought it lightly used roughly 1 year ago and it has largely worked without issue.

Within the last couple weeks I've noticed that the steam wand was leaking water from the steaming tip - a very slow leak, a drop every once in a while. I almost never steam milk so I didn't worry about it too much - I know this machine has an issue with o-rings wearing out on the steam wand so I figured I would get around to replacing it when I had some time over the summer.

Just this morning though I had a bigger issue. I turned my machine on, let it heat up, and went to make espresso as usual. I usually have my machine running at 205 degrees, and the front LED panel stated it was preheated to this. I pulled my shot, and the last 10 seconds it was making a sound that I hadn't heard before, and the espresso it was pulling was quite weird. Took the portafilter out and ran the machine and it was just producing steam from the grouphead. I turned my machine off/on, and at that point it was saying that my brew boiler was at 225 degrees. I've turned my machine off and unplugged it for now, hoping I didn't do any irreparable damage.

I found this post recently which seemed to have a similar issue:

Breville Dual Boiler: fails to reach the temperature after o-ring replacement

However, I hadn't done any work to the machine yet, unlike the poster in that thread that had all this begin after replacing the o-rings.

I couldn't find any more info on this to know if it's a common issue, or if there is a known fix. Hoping someone here can shed some light on this for me. Appreciate any help!


#2: Post by Diggidy »


I took the top off the Ol' beast and found some water inside. I turned my machine on and let it heat up. Attached a picture of what I found.

The two red circled objects are on the steam boiler. The left most one leaks constantly once at temperature - a slow leak. The right most one does not leak much, until you use the steam wand - then it BURSTS - bubbling out actual water.

I was however able to pull a shot, which worked normally. As I read elsewhere, I suspect the steam from the steam boiler was causing the small PCB/circuit board directly above it to malfunction. With the lid off and that out of harms way, it works again.

So I suspect I will need to change some O rings, and given my leaky steam wand, probably my steam wand ball valve? Any idea where to get these currently - most places seem to be sold out. Also, which O rings will I need specifically?



#3: Post by pcrussell50 »

Good boy! You sleuthed out your problem using the resources available. And your conclusions are exactly right:

1) when the small high current board that sits above the steam boiler gets wet from steam, it either goes into runaway heating OR... it trips your GFCI on power up. The fix is to keep it dry, and that is done by replacing the o-rings that have worn out and are no longer sealing right. With the lid off and the machine warmed up, you should wiggle all of the potential leakers:

finding a leak:
fixing the leak:
verifying the repair:

2) steam ball valve drip... this occurs because the PTFE seals inside the valve, that press up against the ball, cold flow and become "loose". Fortunately Breville gave us a serviceable valve, so we can disassemble it and service the seals. This is most easily done by flipping over the seals from the conical part that rides on the ball, to the outboard of the ball. This establishes a new seal. And over time, the new face will flow and form itself to the ball again, and eventually begin a slow drip again. Here is the fix:
(Pardon my accent flip. I grew up in Australia, but I've been here for 25 years now and married an American and have American kids, and am an American myself. My accent comes out here and there depending on circumstances).

Pro tip: Once you have opened the top cover, you don't need to put the screws back in. Put them away in a safe place in case you ever need to send it back for a repair service. The top is not cheap sheet metal, and is heavy enough to stay on, unless you take it out in your offshore racing boat running 100mph in heavy seas.

By the way, there are two threads you need to bookmark:

1) the mods and maintenance thread: Breville Dual Boiler Mods and Maintenance

2) the de facto general ownership thread where you can talk all things good or bad, with other BDB owners: Breville Dual Boiler, five+ years on

LMWDP #553


#4: Post by Diggidy »

Awesome - thanks for the info.

I'm just going to replace all the 007 O-rings, the ones on the leaky connections are quite shot. My machine does not have any washers - I guess Breville stopped using them?

Also, does anyone know what size the PTFE washers need to be for the ball valve?

These were linked previously, but there are many size options.