Aurelia boiler overfilling - need ideas
Long time lurker, first time poster.
I just wrote up the whole history of this problem and it ended up being a 3 page Word doc, so I figured I'd start with the basics and give more info when/if it's asked for.
Nuova Simonelli Aurelia volumetric 2-group has been overfilling and blowing the safety valve the past 2 weeks. The problem is intermittent, sometimes the autofill shuts off just fine, sometimes it just keeps going, and I think sometimes it starts filling on its own without the autofill cycle even starting up (can't be sure about that though)
Checked autofill probe, was fine, replaced anyway.
Checked inlet solenoid, seemed good, replaced inlet solenoid, rechecked inlet solenoid, seems good.
Repair shop said main board was fine.
Repair shop replaced brew buttons on right group, thinking that a janky taped-on button was messing with the electronics somehow.
Replaced safety valve just in case.
Stripped power cable and reconnected plug to be sure there's not a ground issue.
The boiler is still overfilling and burping from the safety valve.
Myself, the cafe owner, 2 trusted repair guys with a lot of experience, and the support people at NS are just about out of ideas. Little help? What would you try next?
Replies to This Discussion
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Permalink Reply by Mike Sabol on
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Even though this will sound obvious you have to figure out where the unwanted water is coming from. Is it the fill valve? Is a heat exchanger cracked? Is there a leak in the manual fill valve?
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Permalink Reply by Sam Cat on
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Fill valves have been checked and rechecked a number of times since this all started, we're all good there. Never thought of HX, and honestly I don't really know what it would look like if that was the problem. Can you explain?
We have all been operating under the assumption that the problem is the autofill valve either opening up without the board telling it to (not likely as the problem is intermittent, the valve has been triple checked and is mechanically sound according to the people who know more about it than I do), or not shutting off when it's supposed to. It's figuring out which one, and why...
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Permalink Reply by Mike McGinness on
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Do you have inlet water feed on a pressure regulator? Common problem if inlet pressure above 4bar ~58PSI....
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Ah. No we don't. City pressure runs about 5 bar. You're saying pressure over 4 bar can pop the inlet valve open on its own? That's something to look at, though I don't understand why we would suddenly encounter this problem after 4 years at the same pressure. If the local utility was doing some work on water lines near us that caused spikes in pressure, that might make some sense...but, it wouldn't explain why the Aurelia II we borrowed doesn't have the same problem, would it?
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I just checked - Nuova specifies maximum inlet pressure 5bar 70psi... 3ish bar safer. Most manufacturers specify 4bar max. Too high inlet pressure or weakening valve can indeed let water leak past and overfill the boiler. City water pressure is seldom "the same" but more likely fluctuates somewhat depending on usage demand.
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Well we'll need to get a regulator then! Good to know. Still, might not be our fix. When you say "leak past," do you mean "full-on open valve"? That's what we're seeing. I'd say less than 30 seconds for the boiler to start filling from its hold level, fill past the top of the level gauge, and blow the safety valve.
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Also forgot to mention, I went over our pressure levels one the phone with the NS support guy and he didn't catch our 5bar as a possible problem.
Sam Cat said:Well we'll need to get a regulator then! Good to know. Still, might not be our fix. When you say "leak past," do you mean "full-on open valve"? That's what we're seeing. I'd say less than 30 seconds for the boiler to start filling from its hold level, fill past the top of the level gauge, and blow the safety valve.
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Actually don't know if it's slow leak or sudden fast fill. I had it happened twice on one of my machines (before installing regulator) and was never at the machine when it happened. After installing regulator never happened again. My pressure was around 6bar...
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Well I might have to jump on that before our repair tech get's too carried away. Thanks, nobody has been able to think outside the box yet, erm. But with a brand new valve on our machine...I'd think the borrowed Aurelia II would be having he same problem, and we've ran it constantly for over 5 days with no problems. Within two hours of reinstalling our own machine it overfilled.
Really hoping you've solved my problem!
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Called the city to check on water, they had someone come by. We're averaging 60 psi. Good flow. ?
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It may or may not solve your problem BUT it would eliminate it as a possiblilty! FWIW I use the WATTS 560G 1/4" w/gauge - online lists $59 @ Graingers - picked it at local Graingers $49...
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Permalink Reply by Brady on
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Sorry to be late to the party. I have a couple of thoughts to add to the already excellent suggestions. The fact that the guys in Bellingham are stumped doesn't make me feel optimistic that I can add anything, but I'll try.
What sort of water conditioning system do you use? I've had random overfilling problems when the machine was being fed water with near-zero TDS. The 2 most recent ones appeared weeks or months after installation, and days after the water had changed since it took that long for the water in the boiler to cycle through. This shouldn't be a problem unless you're using an RO system or bottled water.
Any chance your fill valve was installed backwards? I have seen this before - in one case it had even come from a factory (that will remain nameless) that way! Not sure if it would blow open just through water pressure, but installing it backwards would make this easier.
Is the connection between the boiler and ground good? Not sure how that's made - via a ground wire or just conduction through the boiler support to the chassis, but worth checking.
Are you certain that the issue lies with the autofill valve? If so, that would eliminate other possible water sources like heat exchanger leaks. If not, that would be worth checking.
How's the manual fill valve?
Is the fill probe wire good? What about the probe wire terminals? Anything that would interfere with continuity or even increase resistance might fake the brain out.
How old is the unit? Did this problem begin after any other work was done?Hope that helps. Good luck and please post back with your resolution!
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