Strange boiler whistling / whistle noise (Rancilio Silvia) [video]

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

#1: Post by charlano » Mar 24, 2011, 10:15 pm

Hello, I have descaled my Rancilio Silvia V3 for the first time after a year with 2 liters of citric acid solution (2tbsp / liter), in two batches of 20 minutes. I was amazed to see that the water coming out was crystal clear without any apparent scale. I have started to use the Rancilio filter that helps to prevent the scale to clog the machine a month ago, and I think my water is pretty soft anyways. I have also removed and cleaned the grouphead component as I often do + I did a backflush with cafiza... I descaled one more time with no better results.

However, after that, I started to notice a muted whistling noise that seems to come from the boiler as it reaches its temperature. Moreover, I started to notice that the heater starts while pulling a double shot, which was not the case before, as I remember. What can I do for getting rid of the whistling noise ? Is this normal that the heater starts during the shot if I pull the shot right after the light shuts (I have the V3) ? Can I remove the thermostat to put some heat-paste and then put it back on ?

Anyone have experienced something like that before ?

User avatar
HB
Admin

#2: Post by HB » Mar 24, 2011, 10:29 pm

It would be helpful if you posted a video, but I can take a guess...
charlano wrote:However, after that, I started to notice a muted whistling noise that seems to come from the boiler as it reaches its temperature.
If the over-pressure valve is just opening, it can make a squealing noise. If that's the cause, giving it a quarter to half turn tighter would be enough to stop it from chattering.
Dan Kehn

charlano

#3: Post by charlano » Mar 24, 2011, 10:57 pm

Ok, but when I steam, even if there is a high pressure of steam in the boiler, nothing seems to leak and I have a LOT of steam pressure. It sounds more like a resonating whistle sound at a specific time during the heating cycle. When it begins to whistle, I know that I'm at the end of the heating cycle. I have open the top cap and no steam leak or liquid leak at all. If I open the steam knob for a quick purge, it stops and it comes back again as the temperature and/or pressure rises.

However, could you tell me where is the overpressure valve you are talking about ? I'll give it a check.

User avatar
HB
Admin

#4: Post by HB » Mar 24, 2011, 11:05 pm

That may be true, but keep in mind that steam pressure (around 2 bar) is nothing compared to brew pressure (around 9 bar). From Adjusting Rancilio Silvia v3 OPV:

Image
Dan Kehn

charlano

#5: Post by charlano » Mar 25, 2011, 10:09 am

Yes I know that, however I don't understand what brew pressure have to do with that and how changing the OPV setting would change anything to my problem, since the sound is only noticeable when heat is applied, not during the pump is on.

BTW thanks for the answers.

User avatar
HB
Admin

#6: Post by HB » Mar 25, 2011, 10:23 am

When heat is applied, the water in the boiler expands. In this case, the over-pressure valve may open a tiny bit to reduce the pressure. If you open the steam valve and the noise stops immediately, it's the over-pressure valve.
Dan Kehn

charlano

#7: Post by charlano » Mar 26, 2011, 7:21 am

The OPV isn't just working during the brewing process to regulate approx 9 Bars of pressure in the coffee bed ? So as my understanding, if the OPV is leaking, I should see water that returns to the tank when I hear that noise right ?

User avatar
HB
Admin

#8: Post by HB » Mar 26, 2011, 1:19 pm

That's correct, the valve above serves two purposes:
  • An expansion valve to prevent the (closed) hydraulics system from being subjected to excessive pressure when the boiler water is heated
  • An over-pressure valve to cap the maximum brew pressure during low-flow extractions (i.e., ristrettos).
To see what I mean, remove the second silicone tubing (the one with a notch at the end) from the water reservoir and instead put it in a cup. Then see how much water drips into it when the boiler goes from cold to hot. It will only be a few drops, but enough to keep the pressure reasonable (without an expansion valve, you risk rupturing weaker fittings and gaskets).

As I originally noted, a squealing OPV was only a guess based on very limited information. If you post a video, we can offer more informed conjecture. Or you can try the simple test I proposed earlier:
HB wrote:If you open the steam valve and the noise stops immediately, it's the over-pressure valve.
Dan Kehn

onthego

#9: Post by onthego » Mar 26, 2011, 6:14 pm

charlano wrote:
However, after that, I started to notice a muted whistling noise that seems to come from the boiler as it reaches its temperature. Moreover, I started to notice that the heater starts while pulling a double shot, which was not the case before, as I remember. What can I do for getting rid of the whistling noise ? Is this normal that the heater starts during the shot if I pull the shot right after the light shuts (I have the V3) ? Can I remove the thermostat to put some heat-paste and then put it back on ?

Anyone have experienced something like that before ?
Does the whistling only occur while the machine is warming up? Does it stop once it has reached operating temperature? My Silvia makes a high pitched sound during warm up sometimes but this stops once she has reached operating temperature. I have read accounts of others experiencing the same thing.

Cold water from the reservoir rushes into the boiler immediately when you start your pump to pull a shot with the resultant drop in temperature. It sounds like your boiler brew thermostat is sensing that more quickly than before. I am not sure why that would be.

charlano

#10: Post by charlano » Mar 27, 2011, 9:46 pm

onthego: that is exactly that. It sounds more like a reasoning kind of sound that COULD BE normal. It is more a whistle noise than a hissing noise. The noise begins at a precise point in the heating. When the sound stops (by itself) I know there is about 20 more seconds before the boiler reaches its full temp and then goes off. However, what is strange is that I had never noticed this before the first descale.

Not sure if it do it again past that temp (with the steam switch ON). I will try to do more test and make a video.

Thanks for your help.