Rocket Appartamento over pressure/loud squealing?

#1: Post by **goodbyegalaxy** » March 10th, 2021, 9:45 pm

This morning I was awoken by a very loud squealing noise. At first I thought it sounded a big power drill coming from outside somewhere. Kind of like the pulsating high-pitched whine of a power tool. It stopped for a bit, then started again. As I was looking out the window my wife went downstairs and as the noise happened a third time, she realized it was the espresso machine (which starts every morning on a timer). She saw steam coming out of the steam wand, the hot water wand, and the group head. She tightened the steam and water valves which made more steam come out of the group head. Then she turned it off.

After it cooled down I turned it back on. I noticed the boiler pressure climbed past the red line (1.5 bar) and up to around 2 bar. I opened the valves to lower the pressure a bit. When I closed them the pressure continued to drop down to 1.5, then I heard the boiler click on and it started climbed again. Previously I have had the pressure set at about 1.5 and have never noticed it getting higher than that.

I have found a few posts talking about bad pressurestats causing the pressure relief valve to go off, but nothing about steam spewing out of all of these places and nothing about the NOISE. My only guess is the relief valve has gotten stuck at some point and my pressurestat failed, resulting in this failure mode?

#2: Post by **JRising** » March 11th, 2021, 10:06 am

Open the top, see if it's wired with the pressostat in series with the element or is using the powerboard's relay to death.
Are the wires to the pressostat thick or thin? The Appartamento was wired both ways in bygone years.

So, what you were woken to was the safety valve blowing off excess pressure because the boiler had overheated. We can help you determine why it happened and how to fix it, but there could be many causes so you'll have to help us narrow them down.

So, Pressostat is wired with 2 thin wires, both of which go to the powerboard/control box?
Or Pressostat wired with thick wires one comes from the powerboard, the other goes to the element via the safety thermostat on top of the boiler?

In the meantime, keep an eye on it. Whichever component failed is likely to do so again.

March 11th, 2021, 12:01 pm

Thanks for the reply! It appears to be 2 thin wires, both of which go to the powerboard/control box. I've attached a picture.

#4: Post by **JRising** » March 11th, 2021, 1:00 pm

In this case, I expect the relay on the board is getting ready to die. It welded its contacts closed on the carbon buildup it has accumulated, that time you caught it overheating. If it is working fine now, you can pretty safely rule out a cracked element, however there's always the possibility that it was just a sticky pressostat.
Watch its behaviour for the next while and read the Appartamento postings in these forums. Depending on what you find to be the issue, you'll have learned the possibilities of wiring it in series with the element and/or adding a solid state relay or a cheap sacrificial relay that isn't on the powerboard.

Rocket Appartamento not maintaining steam pressure For your weekend reading.

#5: Post by **JRising** » March 12th, 2021, 9:44 am

Additional Note:

You may want to run the machine for a few days with the 4 screws out (2 in the front lid corners, 2 under the reservoir) and the colour panels (inside the walls) and the metal strips that hold the colour panels removed (one more screw on each panel strip) so that when you catch it overheating again you can try this...
Leave it on and overheating. Take out the reservoir. Lift off the top and reservoir carrier as one whole piece. Whack the pressostat with the plastic handle end of a screwdriver and see if it stops heating after a couple seconds...
If whacking the pressostat didn't do it whack the side of the control box and see if it stops heating after a couple seconds.

Whichever item you whacked to shut off the heating is the new suspect. (Stuck diaphragm in the p-stat or stuck contacts in the Powerboard's relay knocked free with a whack).

March 14th, 2021, 5:24 pm

Thanks for that tip. I've been using my machine without the case for the past couple days and of course the pressure has been fine now.

The only thing I changed was adjusting the pressostat half a turn down and some light tapping on it since I read somewhere else it could be some loose scale interfering with it. I'll keep the case off for a while to see if I can narrow it down when it happens again.

#7: Post by **dhowe** » April 18th, 2021, 9:39 am

Did this ever occur again? Or did it go away on its own? I was awaken in the same way. No steam out of the group or anything though.

#8: Post by **Cruizchiu** » July 5th, 2021, 1:16 am

I am also curious about this. I followed the "whacking" method and haven't had problems, but I also don't leave the machine on as long anymore... I'm curious about other diagnoses.

#9: Post by **MrPotatoHead** » October 23rd, 2021, 8:54 pm

goodbyegalaxy wrote:I've been using my machine without the case for the past couple days and of course the pressure has been fine now.

Has it continued to behave? I have the same screaming pressure relief valve that rears its head every few months. Also, I've been getting inconsistent shot times and noticed my pressure is wandering from 1.0 to 1.3 bar so I suspect my pressurestat is failing.

#10: Post by **maxwell** » December 21st, 2021, 11:32 am

I'm having the same issue with a new-to-me Rocket Appartamento that has blown its PRV a couple of times this week.
On my machine, the heating element is wired in series with the pressurestat. I ran the machine without the case this morning and when the pressurestat clicks off, there's actually a visible flash of light through the plastic casing. Is this normal or am I right to suspect carbon buildup on the contacts? Any advice is most welcome as I'm new to this type of machine.