Silvia thermocouple temperature test question

[cajun_brew]

Today I did some temp test on my Silvia and am a little confused.......

I have a thermocouple on top of the boiler and I temp surf down to 107C and get a high reading of 94C in the brew basket using a different thermocouple and no coffee.

I did same test with coffee and thermocouple on shower screen and got a high reading of 83C.

Does the coffee suck that much heat from the water?-----I've read many times 94C is a good temp to start at but not sure if that is supposed to be with coffee or without coffee.

I finally got around to trying some Black Cat for the first time and have pulled some good shots but no great ones, what temp is a good starting point?

Thanks

[HB]

Does the coffee suck that much heat from the water?

Using a different medium than coffee dramatically affects the initial temperature rise. This graph below is from the Bench review of the Scace Thermofilter Temperature Device:

Blue = thermofilter with its plastic "puck", red = TC wire over the basket lip with coffee puck

The peak temperatures however are very close, certainly a lot less than the 11C difference you report. If you are using the "over the lip" approach, be aware that probe placement can make a huge difference, as noted later in the same thread:


Cimbali Junior - puck top and bottom temperatures

Placement a couple millimeters below the surface, more to the left, more to the right, touching the dispersion screen screw... all can change the reading.

I finally got around to trying some Black Cat for the first time and have pulled some good shots but no great ones, what temp is a good starting point?

I brew it at 94C with good results.

[cajun_brew]

Thanks Dan. It must be probe placement; I'm doing the over the lip placement.

[HB]

It takes a lot of measurements with that approach to convince yourself the data is accurate simply because the slightest error in placement will throw readings off. I learned to recognize the common mistakes just by the plot of the recorded data (usually caused by the probe moving off to the side while locking in the portafilter). Oddly I don't have a lot of recorded data on Silvia because I upgraded before investing in better measurement equipment (Fluke 54-II, type T thermocouples, thermofilter, etc.). The temperature profile data I did collect from Mike Walsh's PID'd Silvia was consistent with what I've read from others: Fast temperature increase, peaks around 5-7 seconds, slowly declines around 2C over the rest of the extraction.

[miKe mcKoffee]

It takes a lot of measurements with that approach to convince yourself the data is accurate simply because the slightest error in placement will throw readings off. I learned to recognize the common mistakes just by the plot of the recorded data (usually caused by the probe moving off to the side while locking in the portafilter). Oddly I don't have a lot of recorded data on Silvia because I upgraded before investing in better measurement equipment (Fluke 54-II, type T thermocouples, thermofilter, etc.). The temperature profile data I did collect from Mike Walsh's PID'd Silvia was consistent with what I've read from others: Fast temperature increase, peaks around 5-7 seconds, slowly declines around 2C over the rest of the extraction.

I'm currently struggling with inadequate test equipment to measure my PID'd Silvia.

Ran a series of 28 2oz pulls into styro cup firmly seated in grouphead just like a PF. Therapen punctured through cup to measure. (Therapen <5sec response highly accurate digital thin probe thermometer, just re-calibrated @ 32f & 212f, used by many top Chef's and the FDA inspectors)

I also recalibrated my PID PVOF setting to -15, which yields 200f on PID and 200f at grouphead from thoroughly warmed and idle Silvia. (BTW if not adjusting PVOF that -15 200f setting would equate to 215f PID setting and reading) I had it 5f lower last Saturday so idle PID shots were 5f higher at PF than read on PID, which means most shots were likely pulled too hot, my BAD. And confirmed by smoother better tasting shots since resetting...

First dozen 2oz pulls were with PID at 200f, after the 1st pull each consecutive 2oz pulled as PID reading climbed to 200f. Then I started lowering the start PID temp of the pull to attempt to compensate for too high water temp output. Here comes the actual measured water temps:
1=200f, 2=201, 3=203, 4=203, 5=203, 6=205, 7=205, 8=205, 9=206, 10=206, 11=207, 12=207, lowered PID 13/193f=207, 14/190=207, 15/185=207, 16/180=207, 17/175=206, 18/175=206, 19/175=206, 20/170=205, 20/170=206, 21/170=205, 22/170=205, 23/165=203, 24/165=203, 25/165=203, 26/160=201, 27/160=202, 28/160=201. These were all back to back approx 2oz straight water pulls, so no puck resistance and hence pulled much faster than shots would have been.
Total time for the 28 was only 13 minutes!

How these temp increases would correlate to actual back to back shots I have no idea. I do know based on almost 4 years observation and experience that Silvia does run hotter on back to back shots. This also needs to be taken into account when traditional temp surfing BTW. I NEED one of those "Espresso Machine Thermofilter Temperature Device" that Greg Scace created and carried exclusively by EPNW, for $249.99, ouch! Anyone have one they care to loan me! (I'll gladly put up a deposit )

I tried creating something similar awhile back. I've already drilled a whole in my old stock Rancilio double basket tc fed through with failed paper towel packing attempt to emulate shot. (tried with ground coffee too but the larger hole in basket for tc cause way major gushing channeling!-) What I really need to do is get a 3/8" threaded valve to screw on spare PF to regulate flow, drill hole is said PF for tc and seal, then pack PF to emulate shot, like Greg with the EPNW marketed device. I'll just use the my old style spare Silvia PF I keep backflush blank in so drilling a hole for tc no biggy. Hmmm, on second thought not drill hole in PF itself but get a second blank to feed tc through and seal hole. That way same PF can be used for day to day backflush duty and occasional temp measurements.

After those 28 2oz water pulls let Silvia stabilize, PID temp overshot a whopping 13f before coming back down to 200f as set! Normal a couple degree overshoot after a shot. She was definitely overheated.

Again, this is with tc feeding PID mounted on the top of boiler under the stock brew tstat, the common suggested location. I want to figure out a mounting location closer to the grouphead feed from the boiler and see if it helps.

[miKe mcKoffee]

A fellow homeroaster espresso addict, I mean aficionado, who lives a few blocks from me and has an identically PID pressure mod'd Silvia recently picked up a Thermofilter. (I have to PF gauge, I got off easy!) Both our machines behave virtually the same, both currently with PVOF set -27 for first shot temp accuracy. IE after warmup of an hour or more pull a blank, fill PF etc and temp right on the money with 2f various intrashot (with heater turned on via steam switch start of pull) I just ran a 20 shot Thermofilter test.

Before 1st test Thermofilter shot placed in Silvia for 10 minutes. Then pulled a blank and set Thermofilter on counter for the approximate length of time it would take me to fill PF etc. From experience I know this time to be about 5f before PID back up to set point which is how a ran the series of shots. After first and each subsequent Thermofilter shot flushed screen and PF wiggle with blank like I always do between shots, waiting to lock Thermofilter for next shot until 5f before set point, in this case 200f. I recorded the high and low for each shot. I'd start the shot right as PF came up to 200f, turning on the steam switch then brew switch in rapid succession. All pulls timed 25sec. Should also note my Silvia is auto-filled so initially the tank water fairly warm since Silvia had been on all day but would gradually cool during the testing since constantly being refilled.

Test shot series high low temps during shot
1) 199.9-198.0
2) 203.0-201.0
3) 206.4-203.3
4) 207.5-206.0
5) 210.6-207.5
6) 210.5-208.1
7) 205.5-204.0
207.8-204.5
9) 207.3-205.5
10) 208.3-206.2
11) 209.5-207.8
12) 210.3-208.5
13) 211.1-209.4
14) 212.7-210.8
15) 212.5-210.7
16) 213.0-211.6
17) 213.2-211.8
18) 213.5-212.7
19) 213.7-212.0
20) 213.9-212.6

The good thing I noticed is relatively decent 2f intrashot stability. The bad thing I already knew, intershot all over the ball park. The temp drop shots 7 through 12 or so my guess is the auto-water fill cooling off the tank water. Then temps continued to climb and level off as grouphead heat saturated.

I had been running my offset -15, 12f lower than the test runs -27. This run does tell me that -14 or so is the correct PID offset for temp saturated grouphead during series of shots, but no good for first dozen or so shots until grouphead saturated and temp stabilized.

Obviously time to do the grouphead heater mod, or bag it and get a Brewtus or ...

Just been given the dinners ready so I'll ponder more later!

[AndyS]

I'd start the shot right as PF came up to 200f, turning on the steam switch then brew switch in rapid succession.

Why are you turning on the steam switch?

[miKe mcKoffee]

Why are you turning on the steam switch?

Better intrashot temp stability and eliminates the shot pulsing caused by PID cycling heater.

The first I don't have much data to back it up, only had the Thermofilter since yesterday! However, on today's series of 20 shots intrashot the temp would drop about 2f the first half of the shot, stabilize and actually raise back up a couple tenths by the end of 25sec pull. Behavior was consistent all 20 shots. The lowest temp observed was never at the end of the shot.

Whether eliminating the PID heater cycling pulse actual improves the shot I can't say. Without temp stability I can't pull a series of shots to compare AND my espresso palate likely isn't refined enough for a reliable time spaced tasting test. But also simply because the pulsing caused by heater cycling bugs me!

[AndyS]

Better intrashot temp stability and eliminates the shot pulsing caused by PID cycling heater.

Yeah, but you end up extracting at 210F after a few shots.

[miKe mcKoffee]

Yeah, but you end up extracting at 210F after a few shots. As I said in another reply to you, it seems likely to me that the your "creep up" problem is due to your habit of keeping the steam switch on.

Whether turning the steam switch on or not before shot get about the same PF shot temp increase 1st shot versus down the series, only about 1f lower total increase. I just pulled 20 Thermofilter shots, same procedure as earlier minus turning on steam switch, with gradual increase in shot temp stabilizing about 12f higher than 1st shot by shot 14, while using steam switch overall higher 13f. Somewhat surprising was intrashot stability virtually the same about 2f once group temp saturated. First half dozen shots running more like 2.5f drop. Another difference lowest temp of shots was always at the end of shot without steam switch rather than bottoming out then rising a couple tenths. Also after ending the series of shots without using steam switch PID still overshot over 12f, didn't record the final high before it started coming back down. The reality is even when entertaining I seldom pull more than a half dozen shots back to back. But without stabilizing group to boiler first even that results in about a 8f rise between 1st to 6th shot, not good to say the least.

All this does in my mind is confirm the reasoning and value behind the grouphead heater mod. Get and keep the grouphead at proper temp without needing to run a dozen or so shots for better intershot temp stablize...

[AndyS]

Whether turning the steam switch on or not before shot get about the same PF shot temp increase 1st shot versus down the series, only about 1f lower total increase. I just pulled 20 Thermofilter shots, same procedure as earlier minus turning on steam switch, with gradual increase in shot temp stabilizing about 12f higher than 1st shot by shot 14, while using steam switch overall higher 13f. Somewhat surprising was intrashot stability virtually the same about 2f once group temp saturated. First half dozen shots running more like 2.5f drop. Another difference lowest temp of shots was always at the end of shot without steam switch rather than bottoming out then rising a couple tenths. Also after ending the series of shots without using steam switch PID still overshot over 12f, didn't record the final high before it started coming back down. The reality is even when entertaining I seldom pull more than a half dozen shots back to back. But without stabilizing group to boiler first even that results in about a 8f rise between 1st to 6th shot, not good to say the least.

All this does in my mind is confirm the reasoning and value behind the grouphead heater mod. Get and keep the grouphead at proper temp without needing to run a dozen or so shots for better intershot temp stablize...

This is interesting, I'm surprised that laying off the steam switch was of so little benefit. Thanks for doing the experiment and proving me wrong.

As you probably know, I've often babbled on about how Silvia IS a heat exchanger machine: the heat normally flows from the 230F boiler water to the 170F group as the water makes it way to the PF. You've obviously shown that there's only a limited amount of heat that the group can absorb.

Hmmm...I guess you could always put a cheap thermometer on the group and lower the boiler PID one degree for every degree the group heated up...or something like that!

[miKe mcKoffee]

Hmmm...I guess you could always put a cheap thermometer on the group and lower the boiler PID one degree for every degree the group heated up...or something like that!

That would be nice and I'm sure you know that is the problem with PID boiler only, you can't reliably or quickly during a series of shots! Even two back to back shots the second one will be 3 or 4f higher temp if start of shot at same PID temp reading. Since this year I've been delving into caps and machiattos I may not do the the group heater mod but give in to upgrade for better steam convenience. Waiting to see how the rest of the HB Christmas deals shake out, just wish Chris's dual boiler PID Quick Mill had come out to add to the confusion! Been re-reading and re-reading HX threads etc. but still not so sure I want to HX surf. The Vetrano keeps talking to me with it's rotary pump, if only I can accept and "learn to love" HX! The idea of surfing irks me yet it would only be on the first shot of a series. And the ability to tweak the brew profile by varying the pause is intriguing... The majority of my pulls are either Americano or ristretto with caps & machiatto now and then. Except when entertaining then milk demand higher. And would probably make more caps for Debi & I if steaming wasn't such a PIA with the espresso sitting there crema going flat or milk sitting there while changing brew to steam or steam to brew... Or forgo rotary and maybe the Brewtus II if a decent Christmas sale offered, like back to $1499. (would pull PID from Silvia and install in Brewtus even better temp control ) Sure a LM GS3 would be the ideal not in my near future...

Ignorance is indeed bliss, I should just stay off this site!

[Kristi]

Just my 2 cents... (see sig)

[miKe mcKoffee]

Today I did some temp test on my Silvia and am a little confused.......

I have a thermocouple on top of the boiler and I temp surf down to 107C and get a high reading of 94C in the brew basket using a different thermocouple and no coffee.

I did same test with coffee and thermocouple on shower screen and got a high reading of 83C.

Does the coffee suck that much heat from the water?-----I've read many times 94C is a good temp to start at but not sure if that is supposed to be with coffee or without coffee.

Your with versus without coffee temp difference is very similar to what I've observed styro cup method versus Thermofilter. I believe the huge temp difference observed has less to do with the coffee puck pulling down the shot temp or even tc placement but rather caused by Silvia design of passively heating grouphead. Idle this means grouphead around 25 to 30f lower temp than boiler. Without puck (or simulated puck) 2oz of water flows very fast and the water isn't affected as much by heatsink effect lowering the temp and hence gives a temp reading closer to boiler temp. During shot water flow much slower so more affected by lower temp water path and grouphead. Do a dozen back to back either method and the differential closes because the group becomes heated closer to boiler temp, at least that's been my observations.

And hence why parts coming for PID grouphead heater mod...

[Kristi]

Idle this means grouphead around 25 to 30f lower temp than boiler. Without puck (or simulated puck) 2oz of water flows very fast and the water isn't affected as much by heatsink effect lowering the temp and hence gives a temp reading closer to boiler temp. During shot water flow much slower so more affected by lower temp water path and grouphead. Do a dozen back to back either method and the differential closes because the group becomes heated closer to boiler temp, at least that's been my observations.

And hence why parts coming for PID grouphead heater mod...

Yup. I notice the same. Was very surprised to see it. How hot do you pid your boiler to?

[miKe mcKoffee]

Yup. I notice the same. Was very surprised to see it. How hot do you pid your boiler to?

Currently running 25f offset, tc mounted left screw of boiler tstat. (PID display of 200=225 boiler PID setting) My normal shot procedure is to pull a couple ounces through empty PF into demi, dry & fill PF etc, and pull shot just as PID comes back up to temp. That offset yields approx correct offset for first shot from fully warmed and idle only! (Fully warmed = 1hr or more, I use a timer. If doing Silvia speed warmup all bets are off for any consistent temp 1st shot!) When doing a series of shots, with screen flush and PF w/blank wiggle between shots, 2nd shot will be about 3f higher, third shot in series 6 to 7f higher etc until peaking about 12 to 13f higher than PID reading which was good for 1st shot. I'm looking forward to and (impatiently) waiting for the parts to PID heat control the grouphead and see how much it'll help intershot stability! With grouphead PID pre-heated to desired shot temp I anticipate a 10 to 15f boiler offset will work for fairly consistent temps 1st shot or series of shots.

[Kristi]

Currently running 25f offset, tc mounted left screw of boiler tstat. (PID display of 200=225 boiler PID setting)

is that a form of calibration? set to 200 to get 225? (mine is 7 off but PID has internal offset I can set)

My normal shot procedure is to pull a couple ounces through empty PF into demi,

enough to trigger boiler?

dry & fill PF etc, and pull shot just as PID comes back up to temp. That offset yields approx correct offset for first shot from fully warmed and idle only! (Fully warmed = 1hr or more, I use a timer... If doing Silvia speed warmup all bets are off for any consistent temp 1st shot!)

Yes, it's a bit of a giggle - I've stopped doing it...

When doing a series of shots, with screen flush and PF w/blank wiggle between shots, 2nd shot will be about 3f higher, third shot in series 6 to 7f higher etc until peaking about 12 to 13f higher than PID reading which was good for 1st shot. I'm looking forward to and (impatiently) waiting for the parts to PID heat control the grouphead and see how much it'll help intershot stability! With grouphead PID pre-heated to desired shot temp I anticipate a 10 to 15f boiler offset will work for fairly consistent temps 1st shot or series of shots.

Yes, that is the -thing- and I will be interested to see you post after putting the rope in. Is does make sense... darn it!

Thanks!

[miKe mcKoffee]

is that a form of calibration? set to 200 to get 225? (mine is 7 off but PID has internal offset I can set)

I'm using FUJI PXR3. PVOF setting determines displayed temp versus actual setting, default is zero or no offset. PVOF -25 for 200 displayed with 225f boiler set point.

enough to trigger boiler?

Yes, blasting 2oz or so water through empty PF pulls PID (displayed) down from 200 to about 180f and triggers heater full on initially then quickly going to pulsing. (mine set 1sec cycle time)

Yes, that is the -thing- and I will be interested to see you post after putting the rope in. Is does make sense... darn it!

Thanks!

Yeah, another two bill Silvia upgrade! But I've played with all kinds of scenarios that didn't include changing PID setting during series of shots. Works ok for up to maybe three shots but then heater ramp on too hard combined with grouphead temp saturated just not doable. For instance if first shot 200, pull second shot as PID comes up to 196 yields about 200 shot, third shot in series pull the trigger about 191. But even by third shot the PID heater is in higher ramp rate so harder to hit. By 12th shot of series took starting way down around 160 displayed (185 at boiler) to hit 200f in PF! Entire boiler to grouphead too overheated. And this was with normal my normal flush between shot timing etc procedures and Thermofilter. Basically totally nuts when entertaining. Entertaining seems only solution without active grouphead heating is to lower boiler setting and pull 10 or 12 blanks letting it come up to temp inbetween before starting series of shots for people. Doable but obviously I decided worth $200 to try and eliminate!

[Kristi]

Yeah, another two bill Silvia upgrade! But I've played with all kinds of scenarios that didn't include changing PID setting during series of shots. Works ok for up to maybe three shots but then heater ramp on too hard combined with grouphead temp saturated just not doable. For instance if first shot 200, pull second shot as PID comes up to 196 yields about 200 shot, third shot in series pull the trigger about 191. But even by third shot the PID heater is in higher ramp rate so harder to hit. By 12th shot of series took starting way down around 160 displayed (185 at boiler) to hit 200f in PF! Entire boiler to grouphead too overheated. And this was with normal my normal flush between shot timing etc procedures and Thermofilter. Basically totally nuts when entertaining. Entertaining seems only solution without active grouphead heating is to lower boiler setting and pull 10 or 12 blanks letting it come up to temp inbetween before starting series of shots for people. Doable but obviously I decided worth $200 to try and eliminate!

Don't entertain! )))))))))

Yeah, that's nuts, either way. I am looking to lower the boiler, and I usually only pull 1-2 shots, ... uh-oh - thinking upgrade... No way to sink 200 into the Silvia... which machine would be better? uh-oh - guess I'll go look at ebay commercial. Groan... Damn! But that gradient in the Silvia IS a fact! No ignoring it. Unless you always pull only one shot. Is an E61 really that much better in terms of gradient between boiler and brewscreen?
No way I can afford a killobuk for an Anita.

See why I read these posts! Great stuff!

[miKe mcKoffee]

Don't entertain! )))))))))

It's really bad when those other people happen to be a bunch of fellow homeroasters espresso fiends (I mean friends)!