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Date: 20 Jun 2007 14:00:48
From: hazzmat
Subject: PID machines-does your boiler stay lit during (most of) the shot?
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On a PID equipped single boiler machine, is normal for the boiler to be on
for most of the length of an espresso shot? To people with PID'ed machines:
Is your boiler on during shot pulling? I understand the reason why it would
be turned on, but I'm curious about whether it has ever been determined by
measurements and subjective testing to be better to have the boiler on than
off for the duration of a shot.
Thanks.
--
Get Big Brother out of my email to reply
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Date: 21 Jun 2007 05:48:10
From: cpl593h
Subject: Re: PID machines-does your boiler stay lit during (most of) the shot?
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Perhaps there is already so much water out of the boiler and in the
brew path that it doesn't matter either way.
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Date: 20 Jun 2007 20:34:15
From: jggall01
Subject: Re: PID machines-does your boiler stay lit during (most of) the shot?
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On Jun 20, 8:48 pm, cpl593h <CPL5...@gmail.com > wrote:
> With a smaller boiler machine (a Silvia and similar machines have
> what, 300mL boilers?), it may be advantageous to let the PID do it's
> thing. In my case, it's unnecessary, but for you, as they say, "how
> does it taste?"
Back in January I did some thermologging of a new-style Silvia (the
current POD-capable model). Intent was to confirm that the new
machine would behave the same under PID control as the previous
models.
Along the way, I measured some shot temperature profiles, both before
and after the addition of the PID to the machine.
The profiles measured before the PID was added would not have had the
heater on at any point during the pull. The profiles measured after
adding the PID would have had the heater kick in during the shot (like
hazzmat reported).
The data shows that the shape of the temperature profile is
essentially the same for heater-on and heater-off shots of 25 second
duration (measured with a Scace device).
This makes sense because the lag time between power first going to the
heater and seeing an actual change in the boiler temperature seems to
be around 20-25 seconds on a Silvia.
So this 20-25 second lag probably means that not much effect is going
to be seen during a 25 second shot. Maybe with longer pulls ( >30
seconds) heater-on versus heater-off could start to make a difference.
Jim
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Date: 21 Jun 2007 00:48:07
From: cpl593h
Subject: Re: PID machines-does your boiler stay lit during (most of) the shot?
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My PID cycles off and on during the shot, but I think it's
unnecessary. I interrupt the DC control voltage to the SSR during the
shot to prevent the heater from coming on. The Isomac Zaffiro has an
800mL boiler so the temperature drop from the incoming water is fairly
insubstantial. Not only that, but the instability introduced by the
incoming cool water gives false boiler temperature readings, causing
the PID to overcompensate. I don't have the testing equipment to prove
that this actually raises the water temperature flowing through the
group, but taste tests generally indicate that I prefer the taste of a
shot with the PID switched off. The difference is fairly slight, and I
could probably attribute it to my own inconsistency, but I don't see a
point in keeping the heater cycling during a shot on my machine.
With a smaller boiler machine (a Silvia and similar machines have
what, 300mL boilers?), it may be advantageous to let the PID do it's
thing. In my case, it's unnecessary, but for you, as they say, "how
does it taste?"
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Date: 21 Jun 2007 00:34:29
From: cpl593h
Subject: Re: PID machines-does your boiler stay lit during (most of) the shot?
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My PID cycles off and on during the shot, but I interrupt the DC
control voltage to the SSR during the shot to prevent the heater from
coming on during the shot. For my machine, I think it's unnecessary.
The Isomac Zaffiro has an 800mL boiler so the temperature drop from
the incoming water is fairly insubstantial. Not only that, but the
instability introduced by the incoming cool water gives false boiler
temperature readings, causing the PID to overcompensate. I don't have
the testing equipment to prove that this actually raises the water
temperature flowing through the group, but taste tests generally
indicate that I prefer the taste of a shot with the PID switched off.
With a smaller boiler machine (a Silvia and similar machines have
what, 300mL boilers?), it may be advantageous to let the PID do it's
thing. In my case, it's unnecessary, but for you, as they say, "how
does it taste?"
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Date: 21 Jun 2007 10:47:46
From: I->Ian
Subject: Re: PID machines-does your boiler stay lit during (most of) the shot?
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On Thu, 21 Jun 2007 00:34:29 -0000, cpl593h <CPL593H@gmail.com > wrote:
>My PID cycles off and on during the shot, but I interrupt the DC
>control voltage to the SSR during the shot to prevent the heater from
>coming on during the shot.
Ditto
> For my machine, I think it's unnecessary.
>The Isomac Zaffiro has an 800mL boiler so the temperature drop from
>the incoming water is fairly insubstantial. Not only that, but the
>instability introduced by the incoming cool water gives false boiler
>temperature readings, causing the PID to overcompensate.
I did it more because I found the pulsing of the pump annoying than
anything else. Someday I may get around to measuring the effect at the
puck.
>I don't have
>the testing equipment to prove that this actually raises the water
>temperature flowing through the group, but taste tests generally
>indicate that I prefer the taste of a shot with the PID switched off.
>
The heater does not come on full at the end of the shot as the
Vibiemme 1.8L boiler drops only a degree or two after a shot, well
within the proportional band.The amount of heat added during a shot
with the heater active would be very small. The group temperature has
far more effect.
>With a smaller boiler machine (a Silvia and similar machines have
>what, 300mL boilers?), it may be advantageous to let the PID do it's
>thing.
>In my case, it's unnecessary, but for you, as they say, "how
>does it taste?"
Amen!
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Date: 20 Jun 2007 12:03:37
From: daveb
Subject: Re: PID machines-does your boiler stay lit during (most of) the shot?
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If the controller senses a need for heat -- it turns on the power.
that is its nature. what would be gained by suppressing that??
zero.
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Date: 20 Jun 2007 15:52:40
From: Robert Harmon
Subject: Re: PID machines-does your boiler stay lit during (most of) the shot?
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It depends. On my HX machines it doesn't come on simply because of the
larger boilers (thermal mass) & the resulting *relatively* long lag time
before the TC triggers the PID Cycle.
On Gaggia/Silvia type machines (single multi-use boilers) the element may be
active during a pull because the smaller boilers (thermal mass) result in
the lag time being shorter, resulting in a shorter period before the PID
cycle is triggered.
I imagine some PID's & TC designs result in less lag time but the ones I use
seems to adhere to the above.
So, to answer your questions;
a) yes/no
b) sometimes
c) no
Sorry for the succinctness of my answers but you're asking questions with
too many variables for one-size-fits-all type answers.
--
Robert Harmon
--
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My 'Guidelines For Newbies' - http://www.tinyurl.com/2tnv87
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"hazzmat" <hazzmatUnitedStates@Governmentbellsouth.net > wrote in message
news:kqaei.886$J9.561@bignews7.bellsouth.net...
> On a PID equipped single boiler machine, is normal for the boiler to be on
> for most of the length of an espresso shot? To people with PID'ed
> machines:
> Is your boiler on during shot pulling? I understand the reason why it
> would
> be turned on, but I'm curious about whether it has ever been determined by
> measurements and subjective testing to be better to have the boiler on
> than
> off for the duration of a shot.
>
> Thanks.
>
> --
> Get Big Brother out of my email to reply
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