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Date: 18 Jun 2007 15:03:24
From: Ken Fox
Subject: Boiler Fill Levels Effect PID Shot Temperature Control
I have made a post over on home-barista.com regarding testing I have done on
the impact of boiler fill levels on attempts at controlling shot
temperatures, using one of my PID'd Cimbali Junior Heat Exchanger machines
as the test machine. I have found that by reducing the water fill level in
the boiler, one can obtain tighter temperature control with a PID'd boiler.
This is a fairly obvious observation however it is one that has eluded me
over the last 2 years.

I believe that most people who have incorporated electronic temperature
control into their espresso machines will find that reducing boiler fill
level will give them tighter control over shot temperatures. Although I
have tested this on a particular model of a particular design of machine
(HX), I believe that my results will be transferable to other HX machines,
as well as some single and double boiler systems.

The summary statement is that if you have PID'd an espresso machine, boiler
fill level is an important variable that will effect both the shot
temperatures that you get, as well as the consistency of those measured
temperatures from shot to shot. My suggestion for anyone who would like to
experiment with this, would be to lower the boiler fill level (either
manually or by repositioning the autofill probe) as much as you can but
still consistent with safe operation of your machine, and evaluate the
results. I think you will be pleasantly surprised.

The home barista post can be found here:
http://www.home-barista.com/forums/boiler-fill-level-impacts-shot-temperature-stability-in-pid-d-espresso-machines-t4270.html

Dan Kehn is going to help to reformat the graphs so that the text will be
more readable, however that will not happen until this evening at the
earliest.

If you choose to comment on this post, please do so either here or at
home-barista.com , and not both.

Thank you.

ken






 
Date: 20 Jun 2007 10:32:47
From:
Subject: Re: Boiler Fill Levels Effect PID Shot Temperature Control
My suggestion for anyone who would like to
> experiment with this, would be to lower the boiler fill level (either
> manually or by repositioning the autofill probe) as much as you can but
> still consistent with safe operation of your machine, and evaluate the
> results. I think you will be pleasantly surprised.

Based on the above, i take the liberty to claim the following:

. Buy small boiler machines
. Fuel gauge is more accurate with low gas levels

Cheers!





  
Date: 22 Jun 2007 11:57:22
From: Roger Shoaf
Subject: Re: Boiler Fill Levels Effect PID Shot Temperature Control

<yuvali300@gmail.com > wrote in message
news:1182360767.988729.26890@p77g2000hsh.googlegroups.com...
> Based on the above, i take the liberty to claim the following:
>
> . Buy small boiler machines

Downside would be longer to wait between successive shots.


> . Fuel gauge is more accurate with low gas levels
>

Not necessarily, although if you are talking about a vehicle, It is far more
important to know you are almost out of fuel than knowing that you have
already expended 2 or 3 gallons.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.