Problem with Rocket Cellini Evoluzione

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

#1: Post by JA »

Hi everybody
I hope someone here can help me get my machine going again.
Its been working fine for five years and suddenly it started letting water out from the pressure release valve when brewing. I replaced the valve and cleaned inspected the grouphead. It helped a but but now I find that the brewing pressure gets too high around 14-15 when pulling a shot.
Normally its steady 8-10. It starts with 8-10 for a few seconds and then jumps up to 14 ! !!!
This scares me. Its like its blocked somewhere ..
The pressure switch seems to work ok but there is two nsf units that seems to control the pressure and some other Electric units. I dont know much about the electrics as Im a model builder.
Could this be the rotary pump failing ? I hope its an easy fix.
Has anybody here had the same thing happen or someone having an idea what has happened ?
Jens Andersen Denmark

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homeburrero
Team HB

#2: Post by homeburrero »

JA wrote:it started letting water out from the pressure release valve when brewing. I replaced the valve and cleaned inspected the grouphead. It helped a but but now I find that the brewing pressure gets too high around 14-15 when pulling a shot.
I suspect that you are talking about the expansion/OPV valve here.

If so, I think you may have a rotary pump adjustment that got loose and went way too high and that meant your expansion valve kicked in to limit pressure, then when you replaced with the new valve it was set a little higher. Normally that expansion valve should not open while brewing.

Set your rotary bypass adjustment (see video below) down in the 9 bar neighborhood with a backfush disk in the group. Then you should see the pressure rise to a constant point about 9 bar when pump is on and brewing a shot.

The expansion/OPV valve is there to protect the machine from dangerously high pressures when the HX heats and you have thermal expansion of the water inside the HX. You expect a slight dribble from that valve when the pump is off and the water in the HX is heating up. And when the machine is idle and not pumping, the pressure gauge does not indicate the pressure in the HX. (The gauge is connected to a point between the pump outlet and a check valve in the line to the HX.)

This video may help identify the internals including the Rotary pump adjustment and the location of the OPV/Expansion valve:
http://www.youtube.com/watch?v=KJwq4wR8vds
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

JA

#3: Post by JA »

Thanks HomeBurrero
This is worth a try. Now I thought about it for a day and came to the conclusion that something is stuck in a pipe somewhere. As I inspected the grouphead I found that the green ( its green on my machine ) O ring under the "champion" in the top part of the grouphead is worn and some tiny piece of the O ring is gone.
I will try adjust the pressure as you described and get back here .Thanks again.
Modelbuilder Jens Andersen

JA

#4: Post by JA »

So I adjusted the brew pressure and installed the old opv valve . Why install the old opv valve ? Because something wasnt Logic about it beeing faulthy.
The lokal dealer send me wrong kit for grouphead and the Opv valve was not like the one mounted from Rocket. It happens all the time in a tiny country like Denmark but Italy / Milano is close by. I will order from them.
The adjustment screw for grouphead pressure I had to turn 3-4 full 360 to get the pressure down to 9 bar. The problem came in 1 day and it could not have been the screw turned by "itself" or by accident.
There is something Else in play here. There is these 3 small Electric halves it could be what you Call solenoide valves. I want to test their values and even take the whole machine apart and inspect everything.
The High pressure happened overnight and I learned in a YouTube video that some machines let water out the opv valve if blocked as when we backflush. That was what happened too. The factory checks the flow in 10 seconds to get the right amount of water through the machine. Im still up for ideas ! Im gonna inspect the little Security Valve to see if its free moving after this. The one shown in the video )It hisses ok During Warm up but it actually could be faulthy or dirty.
This machine shall not beat me.
Its a cool machine... when it works that is.
Rocket Cellini Evoluzione / Rotary pump

JA

#5: Post by JA »

Ok. The valve is of another type but it looks as the day it was born ( there is an Oring around a pin with a small weight and nylon Inside the screw where the Oring fits in ..and I dont think it could have been stuck. Sorry cant upload pictures.
On the bottom of the boiler there is a copper tupe and some white residue has build up around the connection !
If that residue is inside the boiler too we might have a problem here ???
Everything Else seems as new and it has never run tapwater.
I just made a cup of capuchino on it and it was fine. I can hear the Sound has changed after adjusting the pressure down .

JRising

#6: Post by JRising »

JA wrote:Ok. The valve is of another type but it looks as the day it was born ( there is an Oring around a pin with a small weight and nylon Inside the screw where the Oring fits in ..and I dont think it could have been stuck. Sorry cant upload pictures.
Okay, I'm just going to interject here, you're now juggling descriptions of 4 different things up in the air. It would be best to focus on one at a time, fix it if it's an issue and leave it alone if it's not an issue.

The Valve quoted above is just a breather valve (or Anti-vacuum valve). It just lets the air out of your boiler as the boiler fills and when it heats up from cold. It has NOTHING to do with the pressure in your brew circuit. It is only there to seal the boiler once the boiler-water gets to boiling point so that the boiler can pressurize. If it leaks a bit of steam once the boiler gets into range (1Bar to 1.2 Bar), then yes, you will want to clean the white residue off of the red o-ring. If it doesn't leak at all, you can leave it alone.

As for the pressure problem. Your machine has a rotary pump that has its own Pump Bypass Relief built in. You should adjust the pump bypass to relieve full pump flow at a pressure well below the machine's OPV/Expansion valve pressure. If the pump's bypass relief is set somewhere in the 9.8 to 10.2 Bar range, then the only dribbles you get over the OPV will be the expansion volume of the water trapped in the heat exchanger (There is a check valve before the heat exchanger, and the brew valve after the heat exchanger is closed) while the heat exchanger is heated up from cold by the boiler around it.

You mentioned an OPV in a grouphead kit. I can't suggest anything with this, the OPV is very different from everything in the grouphead.

regarding "The adjustment screw for grouphead pressure I had to turn 3-4 full 360 to get the pressure down to 9 bar. The problem came in 1 day and it could not have been the screw turned by "itself" or by accident. "... The pump bypass relief may have been rather high for quite a while, it was just a change in your coffee dosing or grinding that allowed enough backpressure to make it show up. Do remember, it's your coffee preparation that regulated the pressure in the brew head. The pump bypass is just a limiter and the expansion valve is for when the system isn't brewing.

Lastly, the 3 solenoid valves... the two sharing a fitting are the pair that work to select your chosen water source. One opens while the other remains closed depending on the position of your switch, reservoir or plumbing. The solenoid under the boiler is the boiler fill solenoid. It opens when the autofill cycle is filling the boiler. No need to do anything with the solenoid valves unless there's something wrong. They are not causing "overpressure problems" in your brew circuit.

I think that covers the topics you've mentioned. I hope it helps you visualize what your machine does.

JA

#7: Post by JA »

Yes thanks for helping me relax a bit and take on one problem at a time. I hear you loud and clear.
. !!Oh yes I have a Mazzer mini and I didnt change coffe. It should be ok ! I adjust the grinder each time I change coffe but now I will try it out for some days to see if its as steady as it used to be .
I understand what you explained about the 3 selenoid valves .. I might not be the best to explain in a foreign language and was kinda confused about OPV Valve and Brew pressure relief valve valve and everything Else I need a few days to let it in.
Thanks for helping so far and explain in detail. Im truly greatfull for this.
Modelbuilder Jens Andersen