HomeRoast Digest


Topic: ? for Tom B > Re: +PID boiler temp to PF calibration (3 msgs / 76 lines)
1) From: miKe mcKoffee
From: "Tom Bellerue" 
Sent: Thursday, June 02, 2005 12:23 PM
<Snip>
It's finally all "starting" to make sense! If just measuring water temp 
flowing out of PF spout that's not the brew temp I want. Tom (SM Tom) 
mentioned about a 20f temp drop from grouphead to pulled shot, duh I 
forgot. So seems for 200f "shot" water temp at grouphead should be about 
220f, correct?
What do your 232f etc PID set temps correlate to your actual grouphead temp 
measurements? Also, have you measured your actual shot temps? If for 
instance 228f "stock" PID set point yields actual 200f shot temp then 
setting PVOF offset -28 would yield 200f set point giving 200f shot and 
displaying 200f. That's what I'm trying to dial in, display correlating to 
actual shot temp not boiler temp.
Kona Kurmudgeon miKe mcKoffee
3rd Annual Pacific Northwest Sweet Maria's Home Roasters Gathering infohttp://mdmint.home.comcast.net/pnwgIII.htmURL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htm

2) From: Tom Bellerue
Hi miKe..:) For me, 228f makes for good taste pulling 'start of 2nd crack' 
roasts, IIRC it'll correspond to 204 at the puck, dropping 6-8 degrees and 
rising again to 1-4 deg below the start temp over a 30 second pull with the 
steam button on. TC is under the left t-stat screw. Start temp should be 
higher for shots in a series, or if just down from steam temp. SV changes 
should be 1 for 1 with brew temp in the effective range. These numbers are 
based on limited testing, someone with a low-error datalogging thermometer 
could give more solid values.
When I PIDed, I got styro test settings around 219-223, then got advice on a 
good range for mid-range roasts: 226-229, got a good thermometer & results 
above, then went on taste and crema color. Love it. >>:)

3) From: miKe mcKoffee
Thanks for the input Tom. Seems no choice if I want the PV offset temp 
display to accurately be the puck temp I need to get a fine guage TC and do 
what you did. Tried measuring the temp of a shot leaving the single spout PF 
with Thermapen, yeah right, just try when you're pulling a ristretto! Shot 
tasted very good too, even licking off the Thermapen;-) Based on your input 
of SV 228 = 204 puck I had PVOF -24 which would if mine the same be 200f 
with SV 200 and nicely temp display 200. With that I set SV to 204 (would 
correspond to stock 232 and 208 puck if you recalled correctly) for another 
Panama LaBerlina ristretto (City+, well pre-2nd). This shot was better than 
the previous two Pan LaBerlina earlier today... I really like the SV and 
displayed temp to being relatively close to actual start of shot temp via 
PVOF setting, glad I called TTIGlobal tech support! Once I get some accurate 
in the puck temp measurements it will be not relatively but will be 
accurate.
miKe


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