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Topic: PID Preference (6 msgs / 203 lines)
1) From: Douglas Shetler
Everyone,
I've been lurking for some time and I enjoy what I read.  Here is my history
and question.  I had been making espresso with a machine I bought off ebay
for a year or so and then began getting a little more serious.  First I
PID's my Gaggia Classic, then did a Stir Fry/Convention Oven off
of instructions on this list.    My question to the group is, what brand of
PID is  preferred.  I bought one off of ebay from Hong Kong  to put  on my
Gaggia Classic just to see if I could do it.  However, I don't think it is
quite up to snuff.  It stabilizes at a temp within 20 minutes of turning on
the gaggia at a temp that I set.  However, when I pull a shot it takes 3
minutes to return to the stabilized temp.  Something tells me that the
Gaggia can do better than this and the return speed is a result of the cheap
PID.  Am I right?
-- 
Doug

2) From: Dan Bollinger
This is a multi-part message in MIME format.
Doug,   It is probably due to poor programming of the PID, the P,I,D =
values in particular.  Dan

3) From: Howellite
This is a multi-part message in MIME format.
I have a Fuji PXR PID on my Gaggia classic and it takes a max of a
minute for it to get back up to temp
 
Paul Andres

4) From: raymanowen
Question: can the pumps in these machines stand to pump pre-heated water-
say 15 to 20 above ambient- into the boiler or HX? A crude pre-heater=
 in
the reservoir could accomplish the job, and it wouldn't need to be accurate=
-
with a PID controller on the main heater.
The main heater would have to supply that much less heat, which would make
it relatively that much more powerful. PID controllers can only control
excess heater power, not compensate for inadequate horsepower.
A properly adjusted PID controller will never allow the process temperature
to deviate from the setpoint more than a fraction of a degree, so there wil=
l
never be any perceptible "recovery" time. Otherwise, you are using heat
faster than the heater can supply the energy. Shot temperature suffers, PID
or no.
The easy way to add heater capacity would be a quick and easy reservoir
pre-heater.
Cheers -RayO, aka Opa!
If 100% isn't enough, it's the Archimedes Spiral all over again...
On 9/16/06, Howellite  wrote:
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5) From: miKe mcKoffee
Close, but not quite and it's already been/being done on a Sivlia. Not
pre-heating the reservoir, but adding a thermoblock from an old Krups =
after
the pump before PID'd boiler. Of course also has PID controlled group =
rope
heater with net result one the most temp stable espresso machines on =
earth
at any price. 
Kona Konnaisseur miKe mcKoffee
URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I =
must
first not know. And in knowing know I know not. Each Personal =
enlightenment
found exploring the many divergent foot steps of Those who have gone =
before.
	From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of
raymanowen
	Sent: Saturday, September 16, 2006 9:11 PM
	
	Question: can the pumps in these machines stand to pump pre-heated
water- say 15 to 20 above ambient- into the boiler or HX? A crude
pre-heater in the reservoir could accomplish the job, and it wouldn't =
need
to be accurate- with a PID controller on the main heater. 
	
	The main heater would have to supply that much less heat, which
would make it relatively that much more powerful. PID controllers can =
only
control excess heater power, not compensate for inadequate horsepower.
	
	A properly adjusted PID controller will never allow the process
temperature to deviate from the setpoint more than a fraction of a =
degree,
so there will never be any perceptible "recovery" time. Otherwise, you =
are
using heat faster than the heater can supply the energy. Shot =
temperature
suffers, PID or no. 
	
	The easy way to add heater capacity would be a quick and easy
reservoir pre-heater.
	
	Cheers -RayO, aka Opa!
	
	If 100% isn't enough, it's the Archimedes Spiral all over again...

6) From: PecanJim
<Snip>
   My question to
   .>cut some text<
<Snip>
Doug,
    The PID sends a weak current to a solid state relay that then opens
and closes the main heating circuit.  If you can check to see if the
relay is providing a constant current when the temperature is
recovering then the PID should be OK, you may have a heater coil
problem.  Have you descaled the pot?
    Jim Gundlach


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