Hi,

This is an issue I've had for a little while and unfortunately, the technician where I bought the machine doesn't seem to be able to source the problem. So here is my story:

About 1 months ago, my Andreja Premium developed a strange metal high pitched intermittent noise when the pressure rose to 9 bar. The noise seemed to be coming from the front left of the machine. When I first told the salesman about that noise, he thought it could be a problem with the solenoid. I brought the machine back to the store so that they could fix it. Upon inspection, the technician found out that the problem was rather coming from the pump and he replaced it by a new one. It appeared that the flow wasn't constant. When I got the machine back, I immediately noticed that the pump was much quieter, the pressure gauge was also showing a more regular flow and the coffee poor looked much better.

This didn't last and 3 days later, the machine came back to its original state: it was noisier, the pressure fluctuated a lot more around the 4 bars during the preinfusion than during those 3 first days and weird noise was back every time the pressure rose to 9 bar. The noise seems to be related to the pressure since the pressure changes when it hums.

I sent the machine back to the shop and reexplained them the problem. I told them that the machine was different during those 3 days but that it didn't last. They accepted to have another look but this time the technician could definitely not find anything wrong with the machine. He had it on for three days and he brewed a lot of coffee with it without noticing any problem. Still he agreed to replace the pump once more for a more powerful one.

Now the machine is back and the "funky metal humming high pitch noise" is still there. I told the seller I was gonna give him a call to let him know how the machine was. I haven't done it so far since I'm afraid of what they might think. They tested and retested the machine without noticing anything wrong.

So is it normal to hear strange rattles on vibe pump machines? I knew that a vibe pump would be noisier but I wasn't expecting to have strange metal noise.

Or is it me who does something wrong? I cannot think of anything though. I adjust the grind to have a correct extraction time and I back flush the machine without detergent after each session.

Or maybe they don't test it properly...?

So what are your thoughts about this? Is this noise normal in your opinion? If not, what could it be?

Thanks

lsf wrote:Hi,

This is an issue I've had for a little while and unfortunately, the technician where I bought the machine doesn't seem to be able to source the problem. So here is my story:

About 1 months ago, my Andreja Premium developed a strange metal high pitched intermittent noise when the pressure rose to 9 bar.

So what are your thoughts about this? Is this noise normal in your opinion? If not, what could it be?

Thanks

Vibe pump driven machines can be noisy, sometimes very noisy. Generally, this is not due to the pump itself being noisy, but rather the vibe pumps shake the bejesus out of the machine and make the case and other parts rattle. If you aren't used to this than you might think something is amiss when in fact it is not.

On the other hand, the problem could be harmonic resonance coming from the plumbing system in the machine, most likely from the overpressure valve ("OPV"). OPVs, which are what you use to adjust the brew pressure, have a spring in them and under certain circumstances you could get a squeal or other noise coming out of the OPV; I have had this problem with my old Cimbali vibe pump machine. There is a tutorial on adjusting the OPV on an Andrea Premium, that I believe is up on the Chris Coffee website but can be found through a link on this website, somewhere, maybe in Dan's review of this machine. You will have to remove the case in order to get at the OPV.

You could try adjusting the OPV back and forth a few times and then get it set back right, around 9 bar. This might solve the problem or you might need to replace the OPV, which may be the culprit in your problem. Or, some other part in the machine may not be properly secured, and an inspection inside the case may well show which part this is. Perhaps all you need to do is to tighten a screw or bolt, or the simple act of removing and then reattaching the case may resolve it.

ken

lsf wrote:About 1 months ago, my Andreja Premium developed a strange metal high pitched intermittent noise when the pressure rose to 9 bar... So what are your thoughts about this? Is this noise normal in your opinion? If not, what could it be?

It's not normal, but my La Valentina makes that high pitched squeal every once and awhile. It's not the pump, because I moved it outside the casing to the cabinet below. Listening for the location, it sounds like the solenoid chattering. I called Jim at 1st-line about it and he said that was a sign of a failing solenoid. Perhaps, but over two years later and still going fine. Like I said, it doesn't happen every time. Depending on my mood, I blamed it on acoustic resonance or espresso gremlins.

Your Andreja Premium doesn't have a solenoid to direct brew water to the group as mine does, so we can eliminate that cause. My theory is that it's the OPV spring "chirping" because of the vibratory pump. Pressure restrictors will sometimes make a similar sound if the incoming pressure is just a tiny bit higher than the threshold of the valve opening, causing the valve to chatter rapidly.

No harm has come to my machine, and it doesn't happen often enough to force me into tinker mode. But if you wish to test my theory, raise the brew pressure to something like 12 bar by adjusting the OPV (instructions). The OPV will not open, and if I'm right, the squealing will stop.

The problem sound is originating from the OPV and I BELIEVE it is due to a little more clearance than necessary internal to the valve. If you set your OPV such that you have around 8.6-8.7 bar with a blind basket, the problem should be eliminated.

The sound is very similar to that sometimes made by a faucet at extremely low flow rates - the combination of the low water flow and any slightly loose/worn internals sets up a vibration which manifests itself with that sound.

Of course, you could also have them replace the OPV but that's not necessarily a sure-fire guarantee because the new one may be just as bad.

Ken Fox wrote:On the other hand, the problem could be harmonic resonance coming from the plumbing system in the machine, most likely from the overpressure valve ("OPV").

HB wrote:My theory is that it's the OPV spring "chirping" because of the vibratory pump. Pressure restrictors will sometimes make a similar sound if the incoming pressure is just a tiny bit higher than the threshold of the valve opening, causing the valve to chatter rapidly.

erics wrote:The problem sound is originating from the OPV and I BELIEVE it is due to a little more clearance than necessary internal to the valve. If you set your OPV such that you have around 8.6-8.7 bar with a blind basket, the problem should be eliminated.

Am I the only one who's weirded out by three similar responses within three minutes of each other?

I do agree that it is both somewhat unusual and refreshing - but NOW - not only can we have various flushing methodologies, we can have various tinkering modes:

passing the time of day tinkering
scheduled tinkering
forced tinkering

erics wrote:....we can have various tinkering modes:

passing the time of day tinkering
scheduled tinkering
forced tinkering

Tinkering by Proxy
Amateur Tinkering
Professional Tinkering
Vulcan Mind Meld Tinkering
WTFIT? Tinkering
Hammer of Doom Tinkering
You'll-Never-Do-that-To-Me-Again Tinkering

FWW +YMMV+IMLTHO
And then, there may be a water input hose that the liner or an internal loose flap/ chunk of STUFF sucks together and little or no water enters the pump and the squeal is that constriction doing its thing. That would account for a pump frying as there would be very little water flow thru to cool it. Another thing to watch is the routing of any hoses, They may crimp and squeal.
Had a similar problem in a car gas line. Nothing showed outside!
Cheers
richard

HB wrote:Am I the only one who's weirded out by three similar responses within three minutes of each other?

The best part is it was almost midnight when answered... (I was asleep in bed for a change).

Back to the original problem -

Is the machine still under a warranty? If so, I would grind up some of the beans you are using, seal them in a plastic bag, and head back to the service facility wherein YOU should demonstrate to them the problem.