I've been having some problems lately with the temperature dropping on my Brewtus IV-R. It never used to do this and I always suspected something was wrong. There is no way the temperature should drop from 96 to 93 after pulling only two shots. Also, not pulling a shot at all but only using the steam wand should not affect the PID temperature but that too would cause the brew temperature to drop.

My dealer tried to convince me this was 'normal' operation.

Anyway, nothing normal about what happened last night.

Last night the unit literally exploded. The mugs I keep on top of the unit were thrown off and smashed on the counter. Obviously one of the boilers blew up but I haven't yet opened the unit to examine the damage.

It's a darn good thing Expobar puts such thick metal plates around the unit or it would be a lot worse.

Unfortunately, it happened at night and resulted in a few hours of flooding before I noticed it in the morning.

I can just imagine what kind of damage awaits when I open it up. Perhaps the unit 'thought' the temperature was much lower than it really was and overheated the boiler. Still, shouldn't there be a safety mechanism for that?

Yes there Is a mechanism for that. Its called a safety valve. And I've never seen an espresso machine or any pressure vessel for that matter-- that didn't have a safety valve or "over pressure valve". Without one or one that is not working/defective- is a bomb with a runaway temp controller. I would take lots of pictures in your investigation.

I opened the unit up last night and found that a hose had either melted, or burst or both. Here's some photos. Does anyone have any ideas why this would have happened?

I can't tell from the pics, but both boilers look intact. I also noticed over temp/current breakers on the top of the boilers. That should protect the boilers from over heating. I also see a lot of split/melted hoses. That machine is going to take some extensive work to sort out the cause.

I'm not saying it should have contributed to the melting hoses, but why did you leave it on through out the night?

Appears to be some serious overheating.
Is there any water in the boiler still ?..if not it could be that for some reason it ran dry and overheated ?
But need much more inspection to figure it out for sure

Thanks guys. I have always left the unit on and it was not on a timer. So, when the hose burst, it was on and stayed on. I'm going to bring it in for service tomorrow and see what the damage is. The hose is easy enough to replace but there is obviously something else wrong and hopefully the service guys can figure that out.

Having a plumbed in machine is great. But, it isn't so great in a situation like this.

Stay tuned.

This is what happens when a boiler bursts. Technically, they do not explode.

Elektra Espresso Machine Explodes in Sainsbury's

That is bizarre. I would not expect a blow water line to produce enough pressure to throw your cups off the cup warmer.

I seem to be getting closer to the bottom of this slowly but surely.

I took my unit in to my local espresso repair shop. They are not an Expobar dealer but very knowledgeable. Here's what they suggested.

They thought the steam pressure started to increase. I keep the steam pressure at about 0.75 Bar. Somehow this may have increased and we're not sure why. It could be due to a bad pressure switch (the thing in the circle) but not sure.

Once that steam pressure built up, the pressure relief valve would have triggered. This is quite a violent experience and does give a loud bang. That could explain why my son said he heard a loud bang during the night. It could also explain how some of the cups on top of the unit got knocked off. What it doesn't explain is why my son didn't let me know about the loud bang. C'est la vie.

Now the unit is filling up with super hot steam. That *could* have melted the hose but not sure. What it could not have done is split the hose on its complete length. That's still a mystery.

Another thought he had was that some how, super hot water from the steam boiler may have 'backflushed' into the tube which could also have melted it. He wasn't sure if the Brewtus had some kind of check valve to prevent this from happening.

I'll stay tuned.

I have seen that exact same machine do the exact same thing. It flooded a building, basically.