Scace Thermofilter Temperature Device - Page 6

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Abe Carmeli
Team HB

#51: Post by Abe Carmeli »

barry wrote:my point is it is very likely the .8F temp variation isn't. it's very likely you're getting the same 1.6F variation, only attenuated by thermal losses to the <cold> instrument.
Indeed so. But how would the results differ if I had cold P/F and coffee there, instead of the thermofilter puck? Greg says his puck and coffee share a similar heat index. So, wouldn't I get the same results?
Abe Carmeli

Abe Carmeli
Team HB

#52: Post by Abe Carmeli »

HB wrote:Abe, are you saying the portafilter AND the thermofilter were cold?
Yes. I use the Thermofiter (entire unit) cold - at room temperature. If the thermofilter puck has the same heat index as real coffee, shouldn't it behave like it when it is cold as well?
Abe Carmeli

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HB
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#53: Post by HB »

Greg or Barry can answer your question authoritatively, but my first blush measurements suggested that a cold thermofilter profile doesn't accurately model a genuine cold basket + puck. However, it correlated nicely with what I expected once the thermofilter and portafilter were at brew temperature, including an allowance for the normal interval for preparing a real puck. These results make sense to me since the heat index of coffee is pretty much zilch (and presumably the thermofilter's puck substitute), but the brass filter and flow rate valve fittings would draw off a lot of heat.
Dan Kehn

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barry

#54: Post by barry »

Abe Carmeli wrote:Indeed so. But how would the results differ if I had cold P/F and coffee there, instead of the thermofilter puck? Greg says his puck and coffee share a similar heat index. So, wouldn't I get the same results?
i don't think it's the plastic which is causing the results you're seeing; rather it's the heat loss to the probe itself, and to the exposed upper circumference of the portafilter basket.

also, i think you're trying to infer more to this device than was intended. it was meant to provide a uniform means for measuring the water temperature at the upper water/coffee boundary. it was not intended to simulate the thermodynamics of a coffee puck during brewing. the coffee does attenuate fluctuations in water temperature; this device was designed to minimize that attenuation to better reflect machine brew water performance, not the whole machine/pf/puck dynamic.

fwiw, the standardized testing protocol for this device calls for the espresso machine to be at operating temperature for at least an hour before the test, with the thermofilter in the brewhead during this warmup period.

--barry "hoping greg writes some instructions for this thing"

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Walter

#55: Post by Walter »

barry wrote:it was not intended to simulate the thermodynamics of a coffee puck during brewing.
...and I venture to say it couldn't do that. Not even if it were intended to do it...

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Walter

#56: Post by Walter »

What Abe noticed here is IMHO quite a normal - buffering - effect of his brewing environment. And if e.g. setting the temperature 1.5F higher and having the PF at room temperature does the trick of improving his espresso (though I am not sure it will), so be it...

After all coffee brewing is not - yet - considered an exact science, it's only that chemistry and physics apply ... as usual...

It's all about the espresso in the cup! Is it? ;)

Abe Carmeli
Team HB

#57: Post by Abe Carmeli »

barry wrote: i think you're trying to infer more to this device than was intended. it was meant to provide a uniform means for measuring the water temperature at the upper water/coffee boundary. it was not intended to simulate the thermodynamics of a coffee puck during brewing. the coffee does attenuate fluctuations in water temperature; this device was designed to minimize that attenuation to better reflect machine brew water performance, not the whole machine/pf/puck dynamic.

--barry "hoping Greg writes some instructions for this thing"
Ok. I see the error of my ways. I need to re-evaluate the practical usage of this device.
Abe Carmeli

gscace

#58: Post by gscace »

barry wrote:
my point is it is very likely the .8F temp variation isn't. it's very likely you're getting the same 1.6F variation, only attenuated by thermal losses to the <cold> instrument.


--barry "rose-colored glasses"
The cold portafilter isn't how you would normally produce the second and third shot if your preference is to keep the pf out of the machine, so I wouldn't do that. My understanding is that you installed the thermofilter into a cold pf, which is a different heat transfer situation than installing the thermofilter in a hot pf. Should attenuate temperature differences during the shot, so the result is not surprising.

-Greg

gscace

#59: Post by gscace »

barry wrote:
i don't think it's the plastic which is causing the results you're seeing; rather it's the heat loss to the probe itself, and to the exposed upper circumference of the portafilter basket.

also, i think you're trying to infer more to this device than was intended. it was meant to provide a uniform means for measuring the water temperature at the upper water/coffee boundary. it was not intended to simulate the thermodynamics of a coffee puck during brewing. the coffee does attenuate fluctuations in water temperature; this device was designed to minimize that attenuation to better reflect machine brew water performance, not the whole machine/pf/puck dynamic.

fwiw, the standardized testing protocol for this device calls for the espresso machine to be at operating temperature for at least an hour before the test, with the thermofilter in the brewhead during this warmup period.

--barry "hoping greg writes some instructions for this thing"
Yeah, I'm working on them. The device is intended to be installed into a hot portafilter and left in the machine to warm up. The reason is as has been described, which is to say that there is significant heat transfer to the brass filter and flowmeter. It's not a perfect heat transfer substitute for a coffee cake, but once heated it is a reasonable and very repeatable substitute. Remember that the object is to learn about the temperature dynamics of your machine in a way that is very reproducible, then make adjustments consistent with what you know is good practice.

I'm working on the instruction set. I'll get a good set out there real soon, like maybe this weekend, as long as the punkin doesn't throw up on her daddy too much. I'm thinking about including the WBC measurement standard as well because it specifies a systematic measurement protocol that works pretty well. Downside of the WBC standard is that the technical justification for the test protocol is included and perhaps pithy reading, although it clarifies a lot of decisions for why the thermofilter is done the way it is. At any rate, the WBC standard is a good piece of work that can be very helpful because it allows all of us to discuss machine performance in response to a standardized set of tests that test a machine from intermittent usage to full-on line out the door panic.

-Greg

gscace

#60: Post by gscace »

Walter wrote: ...and I venture to say it couldn't do that. Not even if it were intended to do it...
This is correct. The thermofilter is a decent first order approximation that isn't too egregiously out of step, once the brass bits are heated up.

-Greg