Posted Fri Nov 23, 2012, 10:30am Subject: Pump "lag" and temperature flux running water tests out of Silvia portafilter
I have been trying to troubleshoot some extraction issues I have been having as of late and decided to use my Thermapen and just monitor the water extraction out of the portafilter. The setup is:
2001 Silvia with Auber PID installed and set to 228 degrees Newer Rancilio Silvia Portafilter with double spout Stock Silvia Double Portafilter
Two things I have noticed that I wanted to get feedback from you all on are:
I start the water flowing out of the empty portafilter and then there is fast flow for the first four seconds. Then for a couple seconds the flow reduces down to almost nothing. It then starts flowing again but not at the intensity of the initial flow. Here's a video I took of the flow.
Having the PID set at 228 I get right around 200 coming out of the portafilter at the start of my timing. By the time I get to about 25 seconds I am seeing around 179.
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 5,761 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Veneziano A1 Grinder: Many different commercial Vac Pot: 40s era Silex Drip: Milita, Bunn&Curtis... Roaster: Cast iron pan, gas burner
Posted Sat Nov 24, 2012, 11:26am Subject: Re: running water tests out of Silvia portafilter
Without the PF, what does the flow look like? It may be a faulty OP valve or the pump may be dirty and in need of replacement. There isn't much else in the pressure system.
When was the last time the machine was descaled? If there is a heavy buildup of scale in the boiler, the heater can not operate properly and you will not be able to heat the water fast enough, the Sylvia has a fairly small boiler and it is very dependent on high heat output from the heater, if the heater has a coating of scale on it, it can not flow heat fast enough to keep up with the fresh water entering the boiler.
There even may be some sludge moving into the water path, slowing down the water flow.
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Is the pump servicable? I don't mind taking it apart to clean it out. I just recently installed the PID and during that time I replaced the OP valve with the adjustable one. I put a pressure gauge on the portafilter and set the OP valve so I saw around 9 barr at the portafilter.
I have always used filtered Brita water in the machine and have descaled on and off over the years. Not entirely consistent. About 8 months ago I started getting into a regular Dezcal routine about every two months. Is the pump serviceable? I don't mind taking it apart to clean it out. Tell me more about the sludge? Scale sludge or something else?
Measure the volume out in 30 seconds, and repeat that out of a wide open wand with pump running. Find the flow rate. A healthy ulka pump is about 10cc/sec.
Standard PID use stabilizes the idle temperature, and does not prevent intrashot drop. Stabilized machine and water temperature help, but you may need to blip the steam switch for a couple seconds just before the shot. Gaggia is a little different in specifics, but similar idea.
Posted Sat Nov 24, 2012, 7:31pm Subject: Re: Pump "lag" and temp flux running water tests out of Silvia portafilter
Thanks for the info. I took some measurements from both the grouphead and the wand. It looks to be close to the 10cc/sec you stated.
The intrashop drop is interesting. I am new to really looking into all this but is it pretty standard for a Silvia to have a temperature drop from ~200 to high 170's by the end of the extraction?
You mentioned 25 seconds of run, but what volume out. That volume is also cold water into the boiler. A double espresso could be about 50 - 60 ml in 25 seconds and that should not give much temperature drop in a temperature stable fully warmed Silvia.
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,223 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Sat Nov 24, 2012, 7:46pm Subject: Re: Pump "lag" and temp flux running water tests out of Silvia portafilter
I also forgot to ask, have you removed the dispersion screen and cleaned the screen and group? That may change the flow and look of water coming out. Suggested above by Calblacksmith.
Posted Sat Nov 24, 2012, 8:26pm Subject: Re: Pump "lag" and temp flux running water tests out of Silvia portafilter
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I also forgot to ask, have you removed the dispersion screen and cleaned the screen and group?
I did my test with the screen in but, yes, both have been verified clean (the screen is new).
How are you measuring those temperatures?
I am using a ThermoWork Thermapen and have the tip of the Thermapen sitting directly under the screen as the water comes out.
You mentioned 25 seconds of run, but what volume out. That volume is also cold water into the boiler. A double espresso could be about 50 - 60 ml in 25 seconds and that should not give much temperature drop in a temperature stable fully warmed Silvia.
Doh! I guess this makes sense. I was getting ~250ml with just the portafilter off and running. I will need to run some tests with actual coffee in place. The whole reason I started posting about this is that I am trying, in vain, to troubleshoot sour shots I am getting and, from what I have read, a lower temperature can cause this.
I should mention I also spent some time today disassembling and reassembling the pump as well as opening up the boiler and taking a look. They both look pretty good (pictures linked below).
Perhaps I should start over in describing my problem but since it's an older machine I just wanted to make sure it was operating within parameters before I really start banging my head against the wall.
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,223 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Sat Nov 24, 2012, 8:35pm Subject: Re: Pump "lag" and temp flux running water tests out of Silvia portafilter
I guessed about the volume. I wanted similar info for the Gaggia and it is not simple. You need a thermocouple over the lip of the PF with a normal brew, or something to simulate the puck and flow. See Scace thermofilter. I made a thermofilter.
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