# Gaggia Classic PID question



## greymda (Oct 6, 2016)

hi,

wanted to hear some thought from the fellows who have a PID installed on their Gaggia Classic.

i've moded mine today with one (XMT7100, PT100) and here's a video from a shot after auto-tune:






as you can see, it starts at 102.5C and after ~17seconds temperature drops to 98.5C and it starts going up.

can someone share their experience with PID? maybe it must be tuned more "aggressively" to respond to temperature drop?


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## GCGlasgow (Jul 27, 2014)

Not sure i'm understanding what your asking but as water is drawn from the boiler its replaced by cold water from the tank hence the temperature drop. It drops on mine also by about the same.


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## greymda (Oct 6, 2016)

yes, exactly.

now reading this (using GC as a pseudo-HX) and this sounds pretty interesting point of view. any thoughts on this?


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## MartinB (May 8, 2011)

It's temperature drop, may I ask what you would have expected to see?


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## greymda (Oct 6, 2016)

MartinB said:


> It's temperature drop, may I ask what you would have expected to see?


well,i thought it would try to actively compensate the drop...


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## MartinB (May 8, 2011)

What is the hysteresis set to?


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## greymda (Oct 6, 2016)

my current values are:

P - 4.5

I - 83

D - 20

souf - 0.2

ot - 2

filt - 0


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## dbeckett (Jan 11, 2016)

Just wondering what the current price is for all of the individual components for pid as you seem to have built yours yourself? Trying to decide between buying a kit or building it myself


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## greymda (Oct 6, 2016)

20USD for the PID + 2 for the PT100 sensor + 4 for the SSR and ~2 for the cables and connectors.

so total about 28$.


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