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Main
Date: 04 Aug 2007 14:48:26
From: Robert Harmon
Subject: Q: heating element & tstat cycles & their impact of deadband
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Clear DayI tried my hand at explaining deadband to a friend by drawing a
picture. Does this adequately explain it or should I use more examples &
detail?
http://www.coffeegeek.com/images/33705/heatingelementcycles01.gif"
--
Robert Harmon
--
http://www.tinyurl.com/mb4uj - My coffee pages.
http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page.
http://www.tinyurl.com/2cr3e2 - I have things for sale here.
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Date: 04 Aug 2007 19:21:26
From: Barry Jarrett
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
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On Sat, 4 Aug 2007 14:48:26 -0500, "Robert Harmon"
<Texas_Coffee@earthlink.net > wrote:
>Clear DayI tried my hand at explaining deadband to a friend by drawing a
>picture. Does this adequately explain it or should I use more examples &
>detail?
how about real data?
http://www.coffeeprojects.com/images/lm_steam_detail.gif
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Date: 06 Aug 2007 21:32:52
From: daveb
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
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the NERVE! REAL data!
hmpphh!
"Barry Jarrett" <barry@rileys-coffee.com > wrote in message
news:5h5ab3hnifjgohklf1rm48m48rcoojsj0d@4ax.com...
> On Sat, 4 Aug 2007 14:48:26 -0500, "Robert Harmon"
> <Texas_Coffee@earthlink.net> wrote:
>
> >Clear DayI tried my hand at explaining deadband to a friend by drawing a
> >picture. Does this adequately explain it or should I use more examples &
> >detail?
>
>
> how about real data?
>
> http://www.coffeeprojects.com/images/lm_steam_detail.gif
>
>
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Date: 04 Aug 2007 22:19:05
From: Robert Harmon
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
|
Howdy Barry!
I do appreciate your sharing of live data. Thank you! And it's very
interesting, but a bit complicated as a teaching tool. I was trying to show
how deadband adds to temperature instability from the time the pump is
turned on until the machine is ready for the next shot.
Do you have any data showing the intra shot differences for a machine pre
PID & after? I'd also be curious about the idling temps of a pre PID & post
PID install that shows how much difference a PID makes as far as maintaining
the preset temps (how tightly can it keep the temps in a zone)?
--
Robert Harmon
--
http://www.tinyurl.com/mb4uj - My coffee pages.
http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page.
http://www.tinyurl.com/2cr3e2 - I have things for sale here.
"Barry Jarrett" <barry@rileys-coffee.com > wrote in message
news:5h5ab3hnifjgohklf1rm48m48rcoojsj0d@4ax.com...
> On Sat, 4 Aug 2007 14:48:26 -0500, "Robert Harmon"
> <Texas_Coffee@earthlink.net> wrote:
>
> >Clear DayI tried my hand at explaining deadband to a friend by drawing a
> >picture. Does this adequately explain it or should I use more examples &
> >detail?
>
>
> how about real data?
>
> http://www.coffeeprojects.com/images/lm_steam_detail.gif
>
>
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Date: 05 Aug 2007 10:01:45
From: Jack Denver
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
|
This would vary somewhat depending on what the deadband of the pstat was
originally. The full size Sirai's have more deadband than the mini pstats
and there are differences among the minis as well. Also, the PID
installations vary depending on how you've programmed them and also the
placement of the thermocouple. But in general you'd expect to achieve much
tighter control on a PID - Barry's graph shows idle temp to be around +/-4F
around the center point whereas a PID would be under +/-1F.
What I like best about PID is not so much the tight control, which I think
is a little oversold, but the lack of need for maintenance. As an
electromechanical device the pstat is prone to wear - the diaphragms harden,
seals leak, etc. In my Oscar, which had a particularly poor factory
installation (pstat directly on top of boiler without a J-tube) I was
getting less than a year out of mini-pstats. As all-electronic devices, the
PID's give many years of service as long as they are installed properly
(away from heat and moisture which means NOT inside the main enclosure of
the machine).
"Robert Harmon" <Texas_Coffee@earthlink.net > wrote in message
news:13bagcce4k54412@corp.supernews.com...
> Howdy Barry!
>
> Do you have any data showing the intra shot differences for a machine pre
> PID & after? I'd also be curious about the idling temps of a pre PID &
> post PID install that shows how much difference a PID makes as far as
> maintaining the preset temps (how tightly can it keep the temps in a
> zone)?
> --
> Robert Harmon
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Date: 05 Aug 2007 10:32:52
From: Robert Harmon
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
|
Howdy Jack!
I concur with your point about PID's being a *LITTLE* oversold for the
control of temps. Personally, I like them because they eliminate the
constant click-clack of the pstats relays opening & closing. I hadn't even
thought of the maintenance issues; glad you pointed this out.
As for mounting in or out of the machine body, I'm not inclined to agree
with you 100%. Sure, to stick an unprotected electrical box inside an
espresso machine is asking for trouble. First time the espresso machine
springs the tiniest leak (they all do eventually) there goes $50 - $200 for
a new controller. And their ambient temp limits are fairly low - ~135F if I
remember correctly.
But that's doesn't have to be the case: I mounted two PID's on the front
panels of commercial machines. I used Hammond panel mount enclosures;
http://www.hammondmfg.com/1212.htm, a 1212 in one & a 1216 in another. By
sealing the vents in the back of the enclosure & using a 60mm 110VAC fan to
ventilate them, I achieved a clean look and protected the PID at the same
time. The biggest problem in using these enclosures is their length - the
PID *JUST* barely fits inside & it's necessary to get creative in fitting
the wires. But it works & looks nice.
Out of curiosity, what's your thoughts on mounting the PID next to the brass
group as I've seen some folks doing. I'd think locating them in such
environments would expose them to too much heat (unless added ventilation is
used that's not apparent?).
--
Robert Harmon
--
http://www.tinyurl.com/mb4uj - My coffee pages.
http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page.
http://www.tinyurl.com/2cr3e2 - I have things for sale here.
"Jack Denver" <nunuvyer@netscape.net > wrote in message
news:AO2dndDNRrDXRSjbnZ2dnUVZ_oimnZ2d@comcast.com...
snipped
> What I like best about PID is not so much the tight control, which I think
> is a little oversold, but the lack of need for maintenance. As an
> electromechanical device the pstat is prone to wear - the diaphragms
> harden, seals leak, etc. In my Oscar, which had a particularly poor
> factory installation (pstat directly on top of boiler without a J-tube) I
> was getting less than a year out of mini-pstats. As all-electronic
> devices, the PID's give many years of service as long as they are
> installed properly (away from heat and moisture which means NOT inside the
> main enclosure of the machine).
>
>
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Date: 05 Aug 2007 13:26:53
From: Jack Denver
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
|
It's hard to generalize about the best mounting place because each model of
machine is different. For machines with enough clearance, under the drip
tray is a nice cool spot. The mounting box should be covered in a way that
leaks and drips do not affect it - this doesn't have to be elaborate - a
piece of alu. flashing or plastic can do the trick.
On my Oscar, the PID is mounted in a Radio Shack plastic project box and
sits on loosely on my cup tray. Having the PID on top puts it more at eye
level. I don't do much in the way of wire management but a neat
installation is to use a gooseneck from a desklamp. Once you have the PID
mounted on a gooseneck you have a lot of flexibility (literally) on where to
put it. The goosneck can enter the machine from the back or side and you
only need to drill one hole in the case which could be capped off if you
ever wanted to reverse the installation.
There's no doubt that installing the PID right in the front control panel
of the machine (usually next to the group) gives the most "factory" look but
I don't think it is really preferable because of the heat issues (and also
the need to butcher the front panel with the exact right size cutout). A
fan would only work properly if you have ducting to bring in cool outside
air. This is more fancy than I (of the "quick and dirty" school of
(non)craftsmanship) usually go for but someone who is determined to
maintain the appearance of the machine might do this - doing the cutouts
neatly, etc. would probably take more time than the whole rest of the
project.
"Robert Harmon" <Texas_Coffee@earthlink.net > wrote in message
news:13bbrc6f2iv54ec@corp.supernews.com...
> Howdy Jack!
> I concur with your point about PID's being a *LITTLE* oversold for the
> control of temps. Personally, I like them because they eliminate the
> constant click-clack of the pstats relays opening & closing. I hadn't even
> thought of the maintenance issues; glad you pointed this out.
>
> As for mounting in or out of the machine body, I'm not inclined to agree
> with you 100%. Sure, to stick an unprotected electrical box inside an
> espresso machine is asking for trouble. First time the espresso machine
> springs the tiniest leak (they all do eventually) there goes $50 - $200
> for a new controller. And their ambient temp limits are fairly low - ~135F
> if I remember correctly.
>
> But that's doesn't have to be the case: I mounted two PID's on the front
> panels of commercial machines. I used Hammond panel mount enclosures;
> http://www.hammondmfg.com/1212.htm, a 1212 in one & a 1216 in another. By
> sealing the vents in the back of the enclosure & using a 60mm 110VAC fan
> to ventilate them, I achieved a clean look and protected the PID at the
> same time. The biggest problem in using these enclosures is their length -
> the PID *JUST* barely fits inside & it's necessary to get creative in
> fitting the wires. But it works & looks nice.
>
> Out of curiosity, what's your thoughts on mounting the PID next to the
> brass group as I've seen some folks doing. I'd think locating them in such
> environments would expose them to too much heat (unless added ventilation
> is used that's not apparent?).
> --
> Robert Harmon
> --
> http://www.tinyurl.com/mb4uj - My coffee pages.
>
> http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page.
>
> http://www.tinyurl.com/2cr3e2 - I have things for sale here.
>
> "Jack Denver" <nunuvyer@netscape.net> wrote in message
> news:AO2dndDNRrDXRSjbnZ2dnUVZ_oimnZ2d@comcast.com...
>
> snipped
>
>> What I like best about PID is not so much the tight control, which I
>> think is a little oversold, but the lack of need for maintenance. As an
>> electromechanical device the pstat is prone to wear - the diaphragms
>> harden, seals leak, etc. In my Oscar, which had a particularly poor
>> factory installation (pstat directly on top of boiler without a J-tube) I
>> was getting less than a year out of mini-pstats. As all-electronic
>> devices, the PID's give many years of service as long as they are
>> installed properly (away from heat and moisture which means NOT inside
>> the main enclosure of the machine).
>>
>>
>
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Date: 05 Aug 2007 14:40:06
From: Robert Harmon
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
|
Howdy Jack!
I wasn't so much generalizing about physical location as I was about the
impact of so much heat on a PID, especially if it's in an enclosure with no
ventilation. Seems like that would have to at least *shorten* the life
expectancy a *bit*. And butchering is a bit strong; modifying would better
describe my actions. The work is as neat as any factory installation & the
PID is tucked away inside the cases, over the pump, & well away from the
group. That, plus the use of a ventilating fan, keeps temps down below 90
degree Fahrenheit (measured).
Using a panel mount enclosure, if there's room for one, is a piece of cake.
Scribe the outline, drill a few holes, do a bit of Dremeling, and apply a
touch of clear silicone adhesive here & there, and voila - a pretty nice
looking job. Probably not much more time to do this than installing the
goose neck (although I do like the looks of that too). Here's a link that
shows how I used the Hammond 1216 enclosure:
http://home.earthlink.net/~cm_harmon/images/Hammond%201216%20enclosure%20modifications%2001.gif.
I'm getting ready to do a Gaggia Classic, with the an enclosure on top of
the pseudo cup warmer - it'll be mounted at a 25 degree angle and be
ventilated to reduce heat problems.
--
Robert (Sometimes an idea works, sometimes it doesn't; se la vive!) Harmon
--
http://www.tinyurl.com/mb4uj - My coffee pages.
http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page.
http://www.tinyurl.com/2cr3e2 - I have things for sale here.
"Jack Denver" <nunuvyer@netscape.net > wrote in message
news:VbOdnZ4tZfrAlSvbnZ2dnUVZ_ramnZ2d@comcast.com...
> It's hard to generalize about the best mounting place because each model
> of machine is different. For machines with enough clearance, under the
> drip tray is a nice cool spot. The mounting box should be covered in a
> way that leaks and drips do not affect it - this doesn't have to be
> elaborate - a piece of alu. flashing or plastic can do the trick.
>
> On my Oscar, the PID is mounted in a Radio Shack plastic project box and
> sits on loosely on my cup tray. Having the PID on top puts it more at eye
> level. I don't do much in the way of wire management but a neat
> installation is to use a gooseneck from a desklamp. Once you have the PID
> mounted on a gooseneck you have a lot of flexibility (literally) on where
> to put it. The goosneck can enter the machine from the back or side and
> you only need to drill one hole in the case which could be capped off if
> you ever wanted to reverse the installation.
>
> There's no doubt that installing the PID right in the front control panel
> of the machine (usually next to the group) gives the most "factory" look
> but I don't think it is really preferable because of the heat issues (and
> also the need to butcher the front panel with the exact right size
> cutout). A fan would only work properly if you have ducting to bring in
> cool outside air. This is more fancy than I (of the "quick and dirty"
> school of (non)craftsmanship) usually go for but someone who is
> determined to maintain the appearance of the machine might do this - doing
> the cutouts neatly, etc. would probably take more time than the whole rest
> of the project.
>
>
>
>
> "Robert Harmon" <Texas_Coffee@earthlink.net> wrote in message
> news:13bbrc6f2iv54ec@corp.supernews.com...
>> Howdy Jack!
>> I concur with your point about PID's being a *LITTLE* oversold for the
>> control of temps. Personally, I like them because they eliminate the
>> constant click-clack of the pstats relays opening & closing. I hadn't
>> even thought of the maintenance issues; glad you pointed this out.
>>
>> As for mounting in or out of the machine body, I'm not inclined to agree
>> with you 100%. Sure, to stick an unprotected electrical box inside an
>> espresso machine is asking for trouble. First time the espresso machine
>> springs the tiniest leak (they all do eventually) there goes $50 - $200
>> for a new controller. And their ambient temp limits are fairly low -
>> ~135F if I remember correctly.
>>
>> But that's doesn't have to be the case: I mounted two PID's on the front
>> panels of commercial machines. I used Hammond panel mount enclosures;
>> http://www.hammondmfg.com/1212.htm, a 1212 in one & a 1216 in another. By
>> sealing the vents in the back of the enclosure & using a 60mm 110VAC fan
>> to ventilate them, I achieved a clean look and protected the PID at the
>> same time. The biggest problem in using these enclosures is their
>> length - the PID *JUST* barely fits inside & it's necessary to get
>> creative in fitting the wires. But it works & looks nice.
>>
>> Out of curiosity, what's your thoughts on mounting the PID next to the
>> brass group as I've seen some folks doing. I'd think locating them in
>> such environments would expose them to too much heat (unless added
>> ventilation is used that's not apparent?).
>> --
>> Robert Harmon
>> --
>> http://www.tinyurl.com/mb4uj - My coffee pages.
>>
>> http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page.
>>
>> http://www.tinyurl.com/2cr3e2 - I have things for sale here.
>>
>> "Jack Denver" <nunuvyer@netscape.net> wrote in message
>> news:AO2dndDNRrDXRSjbnZ2dnUVZ_oimnZ2d@comcast.com...
>>
>> snipped
>>
>>> What I like best about PID is not so much the tight control, which I
>>> think is a little oversold, but the lack of need for maintenance. As an
>>> electromechanical device the pstat is prone to wear - the diaphragms
>>> harden, seals leak, etc. In my Oscar, which had a particularly poor
>>> factory installation (pstat directly on top of boiler without a J-tube)
>>> I was getting less than a year out of mini-pstats. As all-electronic
>>> devices, the PID's give many years of service as long as they are
>>> installed properly (away from heat and moisture which means NOT inside
>>> the main enclosure of the machine).
>>>
>>>
>>
>
>
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Date: 04 Aug 2007 22:51:14
From: Barry Jarrett
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
|
On Sat, 4 Aug 2007 22:19:05 -0500, "Robert Harmon"
<Texas_Coffee@earthlink.net > wrote:
>I was trying to show
>how deadband adds to temperature instability from the time the pump is
>turned on until the machine is ready for the next shot.
>
except your graph shows nothing to do with instability due to pump
activity...
>Do you have any data showing the intra shot differences for a machine pre
>PID & after? I'd also be curious about the idling temps of a pre PID & post
>PID install that shows how much difference a PID makes as far as maintaining
>the preset temps (how tightly can it keep the temps in a zone)?
i've got lots of data, but perhaps not useful for your purposes as
most of it is LM and not heat exchanger.
let me root around the directory a bit....
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Date: 04 Aug 2007 13:20:41
From: jggall01
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
|
On Aug 4, 3:48 pm, "Robert Harmon" <Texas_Cof...@earthlink.net > wrote:
> Clear DayI tried my hand at explaining deadband to a friend by drawing a
> picture. Does this adequately explain it or should I use more examples &
> detail?
>
> http://www.coffeegeek.com/images/33705/heatingelementcycles01.gif"
On a real machine the cycles will be highly unsymmetrical, with the
cooling phases being drawn out 5X-10X longer than the heating phases.
Jim
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Date: 04 Aug 2007 20:23:58
From: Robert Harmon
Subject: Re: Q: heating element & tstat cycles & their impact of deadband
|
jggall01 <jggall01@yahoo.com > wrote in news:1186258841.445623.98760
@b79g2000hse.googlegroups.com:
> On Aug 4, 3:48 pm, "Robert Harmon" <Texas_Cof...@earthlink.net> wrote:
>> Clear DayI tried my hand at explaining deadband to a friend by drawing a
>> picture. Does this adequately explain it or should I use more examples &
>> detail?
>>
>> http://www.coffeegeek.com/images/33705/heatingelementcycles01.gif"
>
> On a real machine the cycles will be highly unsymmetrical, with the
> cooling phases being drawn out 5X-10X longer than the heating phases.
>
> Jim
>
>
Also the tstat/pstat operating range would be narrower than I've made it in
this much-simplified drawing.
Robert Harmon
--
http://www.tinyurl.com/mb4uj - My coffee pages.
http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page.
http://www.tinyurl.com/2cr3e2 - I have things for sale here.
Remove "ZED" from address if replying by email.
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