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Main
Date: 27 Dec 2006 19:16:18
From:
Subject: PID to Puck temp spread
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Just got my Extech and really like it. I had no real idea what the
water temp at the puck was but Silvia wasn't performing as I expected
and suspected that it was temp, pressure, lousy technique, etc.
After adjusting the OPV from 11 bar to 8.5-9.0 big improvement in the
pour, slightly better shot but not great.
Comes the Extech...PID was set at 224 (dunno why but that seemed as
good a number as any)
temp at the puck during the shot was 213! Lowered PID, let Silvia
stabilize for 30 min..measured again. Rinse and Repeat, Rinse and
repeat.
Now the PID is set at 205 and temp at the puck is 199-200. Major
improvement in the shots. Actually tasting stuff like citrus,
chocolate, etc. Nice!
Finally the question: Is this close spread from PID temp to measured at
the puck normal?
Stan
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Date: 08 Jan 2007 08:58:48
From: gscace
Subject: Re: PID to Puck temp spread
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I got an alpha version done before Christmas. I'm building a beta /
pre-production one today and a coupla more next week. I keep
forgetting how much effort is involved in commercializing a new device.
-Greg "Real answer is that it depends on the time demands of Anneke -
age 23 mos."
stan.shire@gmail.com wrote:
> gscace wrote:
> > > Greg, would adding an adjustable bleed valve (on a "T" fitting with the
> > > gauge) to allow a 45-60ml volume in ~25sec give a more accurate
> > > pressure reading or is this much to simplified?
> > > Stan "under pressure" S
> >
> > Yes. The difficulty is in finding a good needle valve and then keeping
> > it clean. Needle valves suitable for this run a bit of cash and the
> > orifice size is very small and will get plugged up with coffee
> > particles unless you are scrupulously clean. I'm working on a
> > reasonable solution to the problem that will allow folks to make this
> > measurement properly.
> >
> > -Greg
> Since your solution will be infintely more elegant than mine, I'll
> wait. Any idea when it will be revealed?
> Stan
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Date: 04 Jan 2007 13:00:55
From: jggall01
Subject: Thermolog data for new pod-capable Silvia
|
jggall01 wrote:
> Eric Svendson wrote:
>
> > With a boiler water temperature of 238-239, I get 199-200 measured with
> > Greg's Thermofilter after about a 45 minute warm-up from cold. These boiler
> > water temperatures correspond to a boiler surface temperature of 228-229 or
> > thereabouts.
>
> Ditto.
>
> Just finished tuning a controller on one of the new "Pod Silvia's." To
> help answer some of the questions on this thread, I did a fairly
> extensive temperature profile on the machine. I'll probably post some
> of the details on my web site in the coming days (weeks?), but here is
> the executive sumy:
>
> - when referring to boiler temp it is as measured directly under the
> stock brew tstat
> - when referring to brew temp it is as measured on Scace Thermofilter
> device
> - t/c sensors type T, SLE
> - temps measured on Omega HH506RA digital thermometer, logged to PC
> over RS232
>
> - stock brew tstat
> - ON = boiler temp 195F (light on)
> - OFF = boiler temp 225F (light off)
> - peak = boiler temp 240F (approx. 35 seconds after light off)
> - brew temp = 195F if shot is pulled at hottest point of boiler
> cycle
> - brew temp = 185F if shot is pulled at coolest point of boiler
> cycle
> - no way to get a higher brew temp than 195F on this stock Silvia
> (interesting)
> - average boiler temp = (240+195) * 0.5 = 218F (10F lower than PID
> setting)
>
> - PID control at 228F (Watlow controller, calibrated immediately prior
> to test)
> - pulled multiple shots, with some intershot variation (intrashot
> profile pretty level)
> - "walkup" shots after machine at idle for 10 minutes or more --->
> 199F to 202F
> - sequential shots ---> 199F to 204F (temp creep with no flushes
> between shots)
> - temp creep on sequential shots seems to be controlled by cleaning
> flushes
>
> Bottom line is that 228F at the leftmost screw is still about right for
> the "new" boiler if your shot temp target is 200F. So I don't plan any
> changes in our standard controller pre-sets for the "new" machine.
>
> Jim
> www.PIDKits.com
As threatened, I cleaned up some of the data in my previous post above.
The data are available in a new thread over on H-B:
http://www.home-barista.com/forums/viewtopic.php?t=2813
I thought H-B would be better venue for the graphs and discussion. But
below are links to the graphs themselves (you'll have to go to H-B to
read the discussion).
http://www.pidkits.com/images/pod-silvia-thermologs/entire-chart.jpg
http://www.pidkits.com/images/pod-silvia-thermologs/back2back-noflush.jpg
http://www.pidkits.com/images/pod-silvia-thermologs/back2back-with-flushes.jpg
http://www.pidkits.com/images/pod-silvia-thermologs/walkup-shots.jpg
Jim
www.PIDKits.com
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Date: 29 Dec 2006 14:11:08
From:
Subject: Re: PID to Puck temp spread
|
gscace wrote:
> > Greg, would adding an adjustable bleed valve (on a "T" fitting with the
> > gauge) to allow a 45-60ml volume in ~25sec give a more accurate
> > pressure reading or is this much to simplified?
> > Stan "under pressure" S
>
> Yes. The difficulty is in finding a good needle valve and then keeping
> it clean. Needle valves suitable for this run a bit of cash and the
> orifice size is very small and will get plugged up with coffee
> particles unless you are scrupulously clean. I'm working on a
> reasonable solution to the problem that will allow folks to make this
> measurement properly.
>
> -Greg
Since your solution will be infintely more elegant than mine, I'll
wait. Any idea when it will be revealed?
Stan
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Date: 29 Dec 2006 13:43:49
From: gscace
Subject: Re: PID to Puck temp spread
|
> Greg, would adding an adjustable bleed valve (on a "T" fitting with the
> gauge) to allow a 45-60ml volume in ~25sec give a more accurate
> pressure reading or is this much to simplified?
> Stan "under pressure" S
Yes. The difficulty is in finding a good needle valve and then keeping
it clean. Needle valves suitable for this run a bit of cash and the
orifice size is very small and will get plugged up with coffee
particles unless you are scrupulously clean. I'm working on a
reasonable solution to the problem that will allow folks to make this
measurement properly.
-Greg
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Date: 29 Dec 2006 13:04:50
From:
Subject: Re: PID to Puck temp spread
|
jggall01 wrote:
> Stan -
>
> Suggest you hold off on autotuning, for (at least) 2 reasons.
>
> First, autotuning will have no effect on the temperature offset or the
> appropriate SV for your machine. Tuning only has the potential to
> affect stability at SV, the amount of overshoot, and recovery times.
>
> Second, when I evaluated this controller, I got a little better
> performance by manually tuning. Your controller may have also been
> manually tuned for your machine and is already at optimum.
>
> Manual for your controller can be found at:
>
> http://tinyurl.com/y3ab56
>
> Jim
> www.PIDKits.com
Thanks for the link.
Greg, would adding an adjustable bleed valve (on a "T" fitting with the
gauge) to allow a 45-60ml volume in ~25sec give a more accurate
pressure reading or is this much to simplified?
Stan "under pressure" S
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Date: 29 Dec 2006 08:12:59
From: jggall01
Subject: Re: PID to Puck temp spread
|
Stan -
Suggest you hold off on autotuning, for (at least) 2 reasons.
First, autotuning will have no effect on the temperature offset or the
appropriate SV for your machine. Tuning only has the potential to
affect stability at SV, the amount of overshoot, and recovery times.
Second, when I evaluated this controller, I got a little better
performance by manually tuning. Your controller may have also been
manually tuned for your machine and is already at optimum.
Manual for your controller can be found at:
http://tinyurl.com/y3ab56
Jim
www.PIDKits.com
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Date: 29 Dec 2006 07:30:44
From: gscace
Subject: Re: PID to Puck temp spread
|
> Greg
> My seat-of-the-pants pressure measurement was with a liquid-filled
> pressure gauge adapted to the bottom threaded outlet of the pf. No
> basket. Gauge moved up smoothly after a second or two. First few
> readings (with Silvia warmed up for 1 hour) were 10.5-11+. Adjusted the
> opv and brought the pressure down to 8.5-9 bar. Was this measuerment
> method very far off? As I noted, pours are better with fewer blowouts
> and a delayed blonding. Naked pf starts with a ring of beads at the
> circumference and moves pretty smoothly into the center.
> re: temp differentials. I appreciate that your device is very, very
> elegant and beautifully engineered. Wish I could buy one. My crude
> method of placing the bead probe on top of the tamped puck, should be
> sortta close and I'm getting 200 with the PID at 205. I'm baffled by
> the differential that everyone else seems to have (i.e. 200ish at the
> puck and PID at 225+.
> Would autotuning the PID maybe correct what's wrong (and I assume
> something is not quite right?)
> BTW - what is the sequence to autotune the Love 32B?
> Thanks
> Stan
Pumping against the portafilter as you describe gives you the wrong
answer. All water leaving the pump has to go through the pressure
relief valve. When brewing the coffee, only part of the water goes
through the pressure relief valve, with the rest going through the
coffee. The difference in pressure between the stagnation pressure
case (which you measured) and the real world ranges from about 1 bar
(in the cae of machines with rotary pumps and relatively clean flow
paths) to 4.5 bars, which I measured in a machine using a vibe pump
with integral pressure relief valve. In all cases, the stagnation
pressure measurement over-predicts the pressure under brewing
conditions. My understanding is that under-pressurizing is worse than
over-pressurizing. I'd try pumping up the pressure by at least one bar
and tasting the difference. A key concept here is to taste the
difference. As you are discovering, the purpose of all the measurement
stuff is to quantify parameters affecting coffee taste so that you know
what is going on. So taste the coffee and evaluate for yourself the
effects of changing temperature and pressure parameters.
Can't say much about Love controllers since I don't have any experience
with them. I bet they have a website and I bet they have downloadable
manuals for their stuff. A chat with their applications engineers
would prolly be very educational and fun as well.
-Greg
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Date: 28 Dec 2006 20:24:55
From:
Subject: Re: PID to Puck temp spread
|
stan.shire@gmail.com wrote:
> jggall01 wrote:
> > Eric Svendson wrote:
> >
> > > With a boiler water temperature of 238-239, I get 199-200 measured with
> > > Greg's Thermofilter after about a 45 minute warm-up from cold. These boiler
> > > water temperatures correspond to a boiler surface temperature of 228-229 or
> > > thereabouts.
> >
> > Ditto.
> >
> > Just finished tuning a controller on one of the new "Pod Silvia's." To
> > help answer some of the questions on this thread, I did a fairly
> > extensive temperature profile on the machine. I'll probably post some
> > of the details on my web site in the coming days (weeks?), but here is
> > the executive sumy:
> >
> > - when referring to boiler temp it is as measured directly under the
> > stock brew tstat
> > - when referring to brew temp it is as measured on Scace Thermofilter
> > device
> > - t/c sensors type T, SLE
> > - temps measured on Omega HH506RA digital thermometer, logged to PC
> > over RS232
> >
> > - stock brew tstat
> > - ON = boiler temp 195F (light on)
> > - OFF = boiler temp 225F (light off)
> > - peak = boiler temp 240F (approx. 35 seconds after light off)
> > - brew temp = 195F if shot is pulled at hottest point of boiler
> > cycle
> > - brew temp = 185F if shot is pulled at coolest point of boiler
> > cycle
> > - no way to get a higher brew temp than 195F on this stock Silvia
> > (interesting)
> > - average boiler temp = (240+195) * 0.5 = 218F (10F lower than PID
> > setting)
> >
> > - PID control at 228F (Watlow controller, calibrated immediately prior
> > to test)
> > - pulled multiple shots, with some intershot variation (intrashot
> > profile pretty level)
> > - "walkup" shots after machine at idle for 10 minutes or more --->
> > 199F to 202F
> > - sequential shots ---> 199F to 204F (temp creep with no flushes
> > between shots)
> > - temp creep on sequential shots seems to be controlled by cleaning
> > flushes
> >
> > Bottom line is that 228F at the leftmost screw is still about right for
> > the "new" boiler if your shot temp target is 200F. So I don't plan any
> > changes in our standard controller pre-sets for the "new" machine.
> >
> > Jim
> > www.PIDKits.com
>
> Greg
> My seat-of-the-pants pressure measurement was with a liquid-filled
> pressure gauge adapted to the bottom threaded outlet of the pf. No
> basket. Gauge moved up smoothly after a second or two. First few
> readings (with Silvia warmed up for 1 hour) were 10.5-11+. Adjusted the
> opv and brought the pressure down to 8.5-9 bar. Was this measuerment
> method very far off? As I noted, pours are better with fewer blowouts
> and a delayed blonding. Naked pf starts with a ring of beads at the
> circumference and moves pretty smoothly into the center.
> re: temp differentials. I appreciate that your device is very, very
> elegant and beautifully engineered. Wish I could buy one. My crude
> method of placing the bead probe on top of the tamped puck, should be
> sortta close and I'm getting 200 with the PID at 205. I'm baffled by
> the differential that everyone else seems to have (i.e. 200ish at the
> puck and PID at 225+.
> Would autotuning the PID maybe correct what's wrong (and I assume
> something is not quite right?)
> BTW - what is the sequence to autotune the Love 32B?
> Thanks
> Stan
Sorry guys
should have read "Greg, Jim, Caig, Eric, et al" 'cause I REALLY
appreciate the help from everyone.
I'm determined to uncover this differential thing.
Stan
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Date: 28 Dec 2006 19:59:04
From:
Subject: Re: PID to Puck temp spread
|
jggall01 wrote:
> Eric Svendson wrote:
>
> > With a boiler water temperature of 238-239, I get 199-200 measured with
> > Greg's Thermofilter after about a 45 minute warm-up from cold. These boiler
> > water temperatures correspond to a boiler surface temperature of 228-229 or
> > thereabouts.
>
> Ditto.
>
> Just finished tuning a controller on one of the new "Pod Silvia's." To
> help answer some of the questions on this thread, I did a fairly
> extensive temperature profile on the machine. I'll probably post some
> of the details on my web site in the coming days (weeks?), but here is
> the executive sumy:
>
> - when referring to boiler temp it is as measured directly under the
> stock brew tstat
> - when referring to brew temp it is as measured on Scace Thermofilter
> device
> - t/c sensors type T, SLE
> - temps measured on Omega HH506RA digital thermometer, logged to PC
> over RS232
>
> - stock brew tstat
> - ON = boiler temp 195F (light on)
> - OFF = boiler temp 225F (light off)
> - peak = boiler temp 240F (approx. 35 seconds after light off)
> - brew temp = 195F if shot is pulled at hottest point of boiler
> cycle
> - brew temp = 185F if shot is pulled at coolest point of boiler
> cycle
> - no way to get a higher brew temp than 195F on this stock Silvia
> (interesting)
> - average boiler temp = (240+195) * 0.5 = 218F (10F lower than PID
> setting)
>
> - PID control at 228F (Watlow controller, calibrated immediately prior
> to test)
> - pulled multiple shots, with some intershot variation (intrashot
> profile pretty level)
> - "walkup" shots after machine at idle for 10 minutes or more --->
> 199F to 202F
> - sequential shots ---> 199F to 204F (temp creep with no flushes
> between shots)
> - temp creep on sequential shots seems to be controlled by cleaning
> flushes
>
> Bottom line is that 228F at the leftmost screw is still about right for
> the "new" boiler if your shot temp target is 200F. So I don't plan any
> changes in our standard controller pre-sets for the "new" machine.
>
> Jim
> www.PIDKits.com
Greg
My seat-of-the-pants pressure measurement was with a liquid-filled
pressure gauge adapted to the bottom threaded outlet of the pf. No
basket. Gauge moved up smoothly after a second or two. First few
readings (with Silvia warmed up for 1 hour) were 10.5-11+. Adjusted the
opv and brought the pressure down to 8.5-9 bar. Was this measuerment
method very far off? As I noted, pours are better with fewer blowouts
and a delayed blonding. Naked pf starts with a ring of beads at the
circumference and moves pretty smoothly into the center.
re: temp differentials. I appreciate that your device is very, very
elegant and beautifully engineered. Wish I could buy one. My crude
method of placing the bead probe on top of the tamped puck, should be
sortta close and I'm getting 200 with the PID at 205. I'm baffled by
the differential that everyone else seems to have (i.e. 200ish at the
puck and PID at 225+.
Would autotuning the PID maybe correct what's wrong (and I assume
something is not quite right?)
BTW - what is the sequence to autotune the Love 32B?
Thanks
Stan
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Date: 28 Dec 2006 19:44:48
From: jggall01
Subject: Re: PID to Puck temp spread
|
Eric Svendson wrote:
> With a boiler water temperature of 238-239, I get 199-200 measured with
> Greg's Thermofilter after about a 45 minute warm-up from cold. These boiler
> water temperatures correspond to a boiler surface temperature of 228-229 or
> thereabouts.
Ditto.
Just finished tuning a controller on one of the new "Pod Silvia's." To
help answer some of the questions on this thread, I did a fairly
extensive temperature profile on the machine. I'll probably post some
of the details on my web site in the coming days (weeks?), but here is
the executive sumy:
- when referring to boiler temp it is as measured directly under the
stock brew tstat
- when referring to brew temp it is as measured on Scace Thermofilter
device
- t/c sensors type T, SLE
- temps measured on Omega HH506RA digital thermometer, logged to PC
over RS232
- stock brew tstat
- ON = boiler temp 195F (light on)
- OFF = boiler temp 225F (light off)
- peak = boiler temp 240F (approx. 35 seconds after light off)
- brew temp = 195F if shot is pulled at hottest point of boiler
cycle
- brew temp = 185F if shot is pulled at coolest point of boiler
cycle
- no way to get a higher brew temp than 195F on this stock Silvia
(interesting)
- average boiler temp = (240+195) * 0.5 = 218F (10F lower than PID
setting)
- PID control at 228F (Watlow controller, calibrated immediately prior
to test)
- pulled multiple shots, with some intershot variation (intrashot
profile pretty level)
- "walkup" shots after machine at idle for 10 minutes or more --- >
199F to 202F
- sequential shots --- > 199F to 204F (temp creep with no flushes
between shots)
- temp creep on sequential shots seems to be controlled by cleaning
flushes
Bottom line is that 228F at the leftmost screw is still about right for
the "new" boiler if your shot temp target is 200F. So I don't plan any
changes in our standard controller pre-sets for the "new" machine.
Jim
www.PIDKits.com
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Date: 28 Dec 2006 22:58:53
From: Craig Andrews
Subject: Re: PID to Puck temp spread
|
"jggall01" <jggall01@yahoo.com > wrote in message
news:1167363888.701526.176720@79g2000cws.googlegroups.com...
> Eric Svendson wrote:
>
>> With a boiler water temperature of 238-239, I get 199-200 measured
>> with
>> Greg's Thermofilter after about a 45 minute warm-up from cold. These
>> boiler
>> water temperatures correspond to a boiler surface temperature of
>> 228-229 or
>> thereabouts.
>
> Ditto.
>
> Just finished tuning a controller on one of the new "Pod Silvia's."
> To
> help answer some of the questions on this thread, I did a fairly
> extensive temperature profile on the machine. I'll probably post some
> of the details on my web site in the coming days (weeks?), but here is
> the executive sumy:
>
> - when referring to boiler temp it is as measured directly under the
> stock brew tstat
> - when referring to brew temp it is as measured on Scace Thermofilter
> device
> - t/c sensors type T, SLE
> - temps measured on Omega HH506RA digital thermometer, logged to PC
> over RS232
>
> - stock brew tstat
> - ON = boiler temp 195F (light on)
> - OFF = boiler temp 225F (light off)
> - peak = boiler temp 240F (approx. 35 seconds after light off)
> - brew temp = 195F if shot is pulled at hottest point of boiler
> cycle
> - brew temp = 185F if shot is pulled at coolest point of boiler
> cycle
> - no way to get a higher brew temp than 195F on this stock Silvia
> (interesting)
Well, if Rancilio hadn't changed out the "old" brew 110C stat to the
cooler 100C about 3 years ago, this wouldn't be a problem acheiving temp
surfing shots from the 195 - 205F range.
Craig.
> - average boiler temp = (240+195) * 0.5 = 218F (10F lower than PID
> setting)
>
> - PID control at 228F (Watlow controller, calibrated immediately prior
> to test)
> - pulled multiple shots, with some intershot variation (intrashot
> profile pretty level)
> - "walkup" shots after machine at idle for 10 minutes or more --->
> 199F to 202F
> - sequential shots ---> 199F to 204F (temp creep with no flushes
> between shots)
> - temp creep on sequential shots seems to be controlled by cleaning
> flushes
>
> Bottom line is that 228F at the leftmost screw is still about right
> for
> the "new" boiler if your shot temp target is 200F. So I don't plan
> any
> changes in our standard controller pre-sets for the "new" machine.
>
> Jim
> www.PIDKits.com
>
Great info Jim!
Craig.
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Date: 28 Dec 2006 18:00:05
From: Eric Svendson
Subject: Re: PID to Puck temp spread
|
Stan -
To answer the question - no, I do not believe your "new" spread is normal -
something is amiss.
With a boiler water temperature of 238-239, I get 199-200 measured with
Greg's Thermofilter after about a 45 minute warm-up from cold. These boiler
water temperatures correspond to a boiler surface temperature of 228-229 or
thereabouts. If you are doing any steaming prior to making your
measurements, you will put your temperatures into the region you measured
prior to reducing Sv.
If you describe your modus operandi on Silvia, it would be easier to
troubleshoot. HOWEVER, since you seem to be happy with the product at 205,
that's all that counts.
Eric S.
<stan.shire@gmail.com > wrote in message
news:1167275778.420822.180900@n51g2000cwc.googlegroups.com...
> Just got my Extech and really like it. I had no real idea what the
> water temp at the puck was but Silvia wasn't performing as I expected
> and suspected that it was temp, pressure, lousy technique, etc.
> After adjusting the OPV from 11 bar to 8.5-9.0 big improvement in the
> pour, slightly better shot but not great.
> Comes the Extech...PID was set at 224 (dunno why but that seemed as
> good a number as any)
> temp at the puck during the shot was 213! Lowered PID, let Silvia
> stabilize for 30 min..measured again. Rinse and Repeat, Rinse and
> repeat.
> Now the PID is set at 205 and temp at the puck is 199-200. Major
> improvement in the shots. Actually tasting stuff like citrus,
> chocolate, etc. Nice!
> Finally the question: Is this close spread from PID temp to measured at
> the puck normal?
>
> Stan
>
|
| |
Date: 28 Dec 2006 11:17:02
From: jim schulman
Subject: Re: PID to Puck temp spread
|
On 27 Dec 2006 19:16:18 -0800, stan.shire@gmail.com wrote:
>Comes the Extech...PID was set at 224 (dunno why but that seemed as
>good a number as any)
>temp at the puck during the shot was 213! Lowered PID, let Silvia
>stabilize for 30 min..measured again. Rinse and Repeat, Rinse and
>repeat.
>Now the PID is set at 205 and temp at the puck is 199-200. Major
>improvement in the shots. Actually tasting stuff like citrus,
There may be some changes in the machines. Many of the older PIDed
models run at 225F to 230F. When I got the newer crop from Dave, I had
to go down to roughly 220F to get proper shot temperatures. But 205
seems awfully low.
|
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Date: 28 Dec 2006 06:52:38
From: gscace
Subject: Re: PID to Puck temp spread
|
> > www.PIDKits.com
> Greg and Jim
> The pressure was measured "crudely" with a liquid gauge screwed onto
> the portafilter with an adapter (but no basket)
> I did notice an immediate visual improvement in the pours (i.e. less
> "foaming",fewer blowouts, significant delay in blonding) plus better
> overall "look" from the naked pf when I reduced the pressure.
> The pid was installed on a new Silvia by daveb and appears to be stable
> (4-7 degrees overshoot), but pretty slow return to setpoint (4-6 min).
> I checked the Extech against a just-calibrated Fluke at work and they
> did agree.
> My temp measurement (again seat-of-the pants) was done by laying the
> thermocouple bead both on top of the puck and embedding it in the
> packed coffee.
> The scientist in me sez "not scientific enuf" but the shots are much,
> much better.
> Should I try putting the thermocouple probe on top of the boiler to see
> if that reading agrees with the pid display? My differential between
> the PID display of boiler temp and the reading in the PF basket seems
> way closer than anyone else here.
> Thanks
> Stan
Seems like you did things right, although I didn't fully understand
your pressure measurement method. Was there liquid flow out the pf
during the measurement or not? WRT the temperature spread - Maybe Dave
B can tell us what differences there are in the new style Silvia
compared to the older ones. Also maybe Dave enters a temperature
offset into his controllers. Dave?
-Greg
|
| |
Date: 27 Dec 2006 21:02:11
From: jggall01
Subject: Re: PID to Puck temp spread
|
stan.shire@gmail.com wrote:
> My temp measurement (again seat-of-the pants) was done by laying the
> thermocouple bead both on top of the puck and embedding it in the
> packed coffee.
That oughta be pretty good data, assuming brew water running through at
a rate of around 2.5 oz in 25 seconds.
> Should I try putting the thermocouple probe on top of the boiler to see
> if that reading agrees with the pid display?
Don't be surprised/alarmed if you see just a little variation. Going
from memory now, but I think there is around 6F difference just going
from the left screw of the brew tstat to the rightmost screw at the
steam tstat. It took me a good long while to finally get two sensors
mounted on my bench Silvia that agree with each other.
I can't explain your temp readings, but sounds like the bottom line
(good espresso) has been accomplished. Congrats!
Jim
www.PIDKits.com
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Date: 27 Dec 2006 20:36:02
From:
Subject: Re: PID to Puck temp spread
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jggall01 wrote:
> stan.shire@gmail.com wrote:
>
> > Finally the question: Is this close spread from PID temp to measured at
> > the puck normal?
> >
>
> Not in my experience. I would expect more along the lines of
> approximately 25F drop from top of boiler to puck (assuming your sensor
> is very near the old brew tstat). Within the group alone, there is
> somewhere around 6F drop.
>
> The temp you measure in the basket will be dependent on flow rate. One
> of the reasons the Scace device is successful is that Greg calibrated
> the orifice to yield a flow rate of approx. 2.5 oz in 25 seconds.
>
> If you just put a t/c in the basket with no coffee, or if you embed the
> t/c in the puck but the shot goes fast, then you will probably measure
> a higher temperature. You will also measure a higher temperature right
> at the screen as opposed to within the puck itself.
>
> In addition, one of the characteristics of Silvia is to release a short
> burst of very hot water at the outset of your shot. Very quickly
> thereafter, with a normal flow rate, the temperature should stabilize
> to the 200-204F range we are after.
>
> I'm very interested in your data. Please provide some additional
> information about how you are measuring puck temps, and where your PID
> sensor is mounted.
>
> Jim
> www.PIDKits.com
Greg and Jim
The pressure was measured "crudely" with a liquid gauge screwed onto
the portafilter with an adapter (but no basket)
I did notice an immediate visual improvement in the pours (i.e. less
"foaming",fewer blowouts, significant delay in blonding) plus better
overall "look" from the naked pf when I reduced the pressure.
The pid was installed on a new Silvia by daveb and appears to be stable
(4-7 degrees overshoot), but pretty slow return to setpoint (4-6 min).
I checked the Extech against a just-calibrated Fluke at work and they
did agree.
My temp measurement (again seat-of-the pants) was done by laying the
thermocouple bead both on top of the puck and embedding it in the
packed coffee.
The scientist in me sez "not scientific enuf" but the shots are much,
much better.
Should I try putting the thermocouple probe on top of the boiler to see
if that reading agrees with the pid display? My differential between
the PID display of boiler temp and the reading in the PF basket seems
way closer than anyone else here.
Thanks
Stan
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Date: 27 Dec 2006 19:38:49
From: jggall01
Subject: Re: PID to Puck temp spread
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stan.shire@gmail.com wrote:
> Finally the question: Is this close spread from PID temp to measured at
> the puck normal?
>
Not in my experience. I would expect more along the lines of
approximately 25F drop from top of boiler to puck (assuming your sensor
is very near the old brew tstat). Within the group alone, there is
somewhere around 6F drop.
The temp you measure in the basket will be dependent on flow rate. One
of the reasons the Scace device is successful is that Greg calibrated
the orifice to yield a flow rate of approx. 2.5 oz in 25 seconds.
If you just put a t/c in the basket with no coffee, or if you embed the
t/c in the puck but the shot goes fast, then you will probably measure
a higher temperature. You will also measure a higher temperature right
at the screen as opposed to within the puck itself.
In addition, one of the characteristics of Silvia is to release a short
burst of very hot water at the outset of your shot. Very quickly
thereafter, with a normal flow rate, the temperature should stabilize
to the 200-204F range we are after.
I'm very interested in your data. Please provide some additional
information about how you are measuring puck temps, and where your PID
sensor is mounted.
Jim
www.PIDKits.com
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Date: 27 Dec 2006 19:31:45
From: gscace
Subject: Re: PID to Puck temp spread
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Check to make sure that your PID controller or your Extech is properly
configured for the thermocouple type you use. Silvias like mine (2001)
need around 230 in the boiler for 200 at the coffee. The 8.5 to 9 bar
pressure value is too low if you are measuring using the current crop
of portafilter pressure gauges that measure stagnation pressure. I
dunno what the correct stagnation value is, but I bet it's at least 10
bars.
-Greg
stan.shire@gmail.com wrote:
> Just got my Extech and really like it. I had no real idea what the
> water temp at the puck was but Silvia wasn't performing as I expected
> and suspected that it was temp, pressure, lousy technique, etc.
> After adjusting the OPV from 11 bar to 8.5-9.0 big improvement in the
> pour, slightly better shot but not great.
> Comes the Extech...PID was set at 224 (dunno why but that seemed as
> good a number as any)
> temp at the puck during the shot was 213! Lowered PID, let Silvia
> stabilize for 30 min..measured again. Rinse and Repeat, Rinse and
> repeat.
> Now the PID is set at 205 and temp at the puck is 199-200. Major
> improvement in the shots. Actually tasting stuff like citrus,
> chocolate, etc. Nice!
> Finally the question: Is this close spread from PID temp to measured at
> the puck normal?
>
> Stan
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