PIDing a Heat Exchanger, Part Trois

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Date: 17 Jun 2006 10:11:11
From: Ken Fox
Subject: PIDing a Heat Exchanger, Part Trois

This will be a brief, mostly graphic, illustration of a potential issue one
might encounter when PIDing a heat exchanger for purposes of shot
temperature stability. I've previously posted on the topic of PIDing my
Cimbali Junior machines and won't repeat the material that was previously
posted, other than to say that there were obvious differences in the shot
curve shapes obtained and inter-shot recovery times necessary observed in my
two machines, a 10+ year old vibratory pourover ("S") machine and a current
vintage Rotary ("D") machine.

Here are representative curves from the two machines that show the
differences in shot temperature curve shape:

http://img.photobucket.com/albums/v429/kfoxfoie/CimbaliJuniorD1PIDReprogrammed_231F.jpg

(this is the rotary machine)

http://img.photobucket.com/albums/v429/kfoxfoie/JuniorS1PID242pt5ShotSeries.jpg

(this is the vibe machine)

When you look at these curves you will see that two things: the rotary
machine was able to maintain the shot temperature (or even slightly increase
it) in the portion of the curve after the "heat exchanger hump," better than
the vibe, plus the rotary machine could make repeatable shots at a frequency
of one shot per 90 seconds whereas the vibe could only do this every 120
seconds. This pointed to reduced heating efficiency on the part of the
older machine.

I'd assumed that this was due to some differences in the materials used or
the machine HX design over the 7 years separating the manufacturing of the
two machines. I discussed this with a very capable Cimbali technician,
James from Bravo Coffee in Vancouver, Canada. He told me that there was no
difference in the materials used or design of the HX in the two machines and
that the explanation was probably in the length of the water outlet tube in
the HX, something I could "fix."

When I was recently in Vancouver I stopped by Bravo Coffee and picked up a
few parts, including a new HX and a new Water Outlet Tube (my term for the
siphon that transfers the water from the HX to the head of the group). Here
is a picture of these parts which I removed from the old vibe machine:

http://img.photobucket.com/albums/v429/kfoxfoie/HXandWaterOutlet.jpg

The heat exchanger is on the left (please no crude comments:-)); I have
since descaled it but replaced it with the new one in the machine. The
water tube shown is the one I removed; it is distorted in shape a little bit
which presumably relates to it having been used over a 10 year period. It
was taking water out of the HX higher up in the HX than it should have due
to the distortion in its shape. The price I paid for a new HX and a new
tube was approximately $40 Canadian in total, plus a couple of O-rings were
needed; the total cost of the "repair" was about $50CDN (about $45 US).

After replacing the HX and the Water tube, I did very limited Scace Device
testing on the machine; here are the 3 curves I obtained in a mini shot
series:

http://img.photobucket.com/albums/v429/kfoxfoie/243pt5FShotshapeseries.jpg

What you can see is that the CURVE SHAPE of the 10 year old vibe machine is
now more or less identical to that obtained from the newer rotary machine,
AND, a shot sequence every 90 seconds is now obtainable whereas I needed to
allow 120 seconds per shot before (when I say 1 shot per 90 seconds I mean a
30 second shot followed by a 60 second recovery period, 90 seconds in total,
the time we'd probably use to prepare for the next shot anyway).

The "take home" message from this is that if you try to PID your heat
exchanger and are unable to get the sort of results you seek, the reason
might be some minor maintenance or repair issue rather than a problem with
the design of your machine. Small issues such as those shown here can make
big differences if tight temperature control is your intent.

ken

Date: 18 Jun 2006 03:38:17
From: Marshall
Subject: Re: PIDing a Heat Exchanger, Part Trois

On Sat, 17 Jun 2006 10:11:11 -0600, "Ken Fox"
<morceaudemerdeThisMerdeGoes@hotmail.com > wrote:

>This will be a brief, mostly graphic, illustration of a potential issue one
>might encounter when PIDing a heat exchanger for purposes of shot
>temperature stability. I've previously posted on the topic of PIDing my
>Cimbali Junior machines and won't repeat the material that was previously
>posted, other than to say that there were obvious differences in the shot
>curve shapes obtained and inter-shot recovery times necessary observed in my
>two machines, a 10+ year old vibratory pourover ("S") machine and a current
>vintage Rotary ("D") machine.<snip>

Ken,

Your heroic efforts this past year to turn your heat exchanger into a
single boiler have helped push me to the following conclusion:
whatever the advantages of the HX in a commercial environment, they do
not translate to the long idle periods inherent in home use.

Using them means playing "flush-and-pray," instead of having a
reliable temperature. At home, I think the HX is an economic
compromise (and a sensible one). But, if double boilers and heat
exchangers of the same quality were produced at the same price, I can
not imagine why any home user would buy an HX.

I said this to Michael Teahan at lunch recently, and he did not argue
with me. Of course, that could simply have been because he was too
polite to tell me how stupid I am. But, I chose to take as a sign that
I had at least had an arguable case. :-)

Marshall

Date: 17 Jun 2006 22:10:48
From: Ken Fox
Subject: Re: PIDing a Heat Exchanger, Part Trois

"Marshall" <mrfuss@ihatespamearthlink.net > wrote in message
news:8jh992phqskllikcs40baiki4ibil767ua@4ax.com...
> > Ken,
>
> Your heroic efforts this past year to turn your heat exchanger into a
> single boiler have helped push me to the following conclusion:
> whatever the advantages of the HX in a commercial environment, they do
> not translate to the long idle periods inherent in home use.
>
> Using them means playing "flush-and-pray," instead of having a
> reliable temperature. At home, I think the HX is an economic
> compromise (and a sensible one). But, if double boilers and heat
> exchangers of the same quality were produced at the same price, I can
> not imagine why any home user would buy an HX.
>
> I said this to Michael Teahan at lunch recently, and he did not argue
> with me. Of course, that could simply have been because he was too
> polite to tell me how stupid I am. But, I chose to take as a sign that
> I had at least had an arguable case. :-)
>
> Marshall

Marshall,

If i were convinced that double boiler technology was as advanced today as
you seem to think it is, I'd be in full agreement with you.

Here's the condensed crystallized down set of issues to ponder in this
discussion of, and choice of, machine types:

(1) Are actually delivered temps as advertized --- yet to be proven

(2) Are most people capable of tasting differences in brew temp small enough
that it matters -- unclear

(3) Are there maintenance, durability, and longeivity realities that would
push one's choice in one direction or another -- arguably this favors old,
reliable, easily fixed machines for whom there is a large number of dealers,
and choice of knockoff vs. OEM parts.

(4) Cognitive dissonance; is there a likelihood that after having plunked
down beaucoup thousands of dollars that one will be inclined to justify such
expenditure by convincing ones self of the wisdom of said purchase -- highly
likely.

(5) If one already owns a competent espresso machine, one has attained
competent barista skills, and one uses high grade fresh coffee; what is the
likelihood that if blindfolded one could sense obvious improvement when
going from said former competent machine to a dual boiler machine? --
unknown.

ken

Date: 18 Jun 2006 04:06:14
From: Andy Schecter
Subject: Re: PIDing a Heat Exchanger, Part Trois

Marshall wrote:
> Your heroic efforts this past year to turn your heat exchanger into a
> single boiler have helped push me to the following conclusion:
> whatever the advantages of the HX in a commercial environment, they do
> not translate to the long idle periods inherent in home use.
>
> Using them means playing "flush-and-pray," instead of having a
> reliable temperature. At home, I think the HX is an economic
> compromise (and a sensible one). But, if double boilers and heat
> exchangers of the same quality were produced at the same price, I can
> not imagine why any home user would buy an HX.
>
> I said this to Michael Teahan at lunch recently, and he did not argue
> with me. Of course, that could simply have been because he was too
> polite to tell me how stupid I am. But, I chose to take as a sign that
> I had at least had an arguable case. :-)

Hi Marshall:

1. Unfortunately, many of the double boiler machines, save perhaps the Synesso
and the newest LMs, also require a flushing procedure if you want accurate
temps. (It's built into the Barista Competition tech standards, Ted!)
2. Teahan says the Italians seem to get better extractions using a temp
profile that is a few degrees hotter at the beginning of the shot, then cools
down. This is tough to achieve with a double boiler setup, but is relatively
simple with a HX.

Maybe MT isn't suffering from politeness, just fatigue....
--

-Andy S.

http://www.flickr.com/photos/andy_s/sets/
http://tinyurl.com/eh0x

Date: 18 Jun 2006 08:26:55
From: Simpson
Subject: Re: PIDing a Heat Exchanger, Part Trois

In article <Wi4lg.17938$W97.4922@twister.nyroc.rr.com >,
schecter@remove.me.rochester.rr.com says...
snip
> Hi Marshall:
>
> 1. Unfortunately, many of the double boiler machines, save perhaps the Synesso
> and the newest LMs, also require a flushing procedure if you want accurate
> temps. (It's built into the Barista Competition tech standards, Ted!)
snip

Sigh. It shouldn't be. If not doing it results in worse coffee and doing
it results in better coffee, and the judging is only about the coffee,
then people will do it (and beat the snot out of the manufacturers until
they get it right so the hard working baristas don't have to flush
anymore) since it is only about the coffee.

Ted
--
email me at:
tee en jay ess eye em pee ess oh en one-the-number (at) cee oh em cee a
ess tee (dot) en ee tee

ANY other email addie will probably mean I spam-killed your message
unread, by accident, really.

Date: 18 Jun 2006 14:06:50
From: jim schulman
Subject: Re: PIDing a Heat Exchanger, Part Trois

On Sun, 18 Jun 2006 03:38:17 GMT, Marshall
<mrfuss@ihatespamearthlink.net > wrote:

> But, if double boilers and heat
>exchangers of the same quality were produced at the same price, I can
>not imagine why any home user would buy an HX.

Given:

1.Advanced HX machines like the Aurelia
2. the less than Schomeresque curves posted for most double boilers
(the winner there is still Sean Lennon's heavily modded Brewtus),
3. the lack of data concerning which temperature profile is best
(given they are all equally repeatable)

the match isn't over yet.

For regular home use, I can vary the temperature on mine for the first
shot by varying the flush, which is quite convenient for private use.
The main advantage of double boilers is that one can change the
temperature on the front panel, and get **repeated** shots at the
changed shot temperature (after flushing on most DB machines). This
makes double boilers a lot more convenient for testing out new blends,
new tamping techniques, or anything else where one wants to make
before and after comparisons.

Date: 17 Jun 2006 20:24:27
From: jim schulman
Subject: Re: PIDing a Heat Exchanger, Part Trois

On Sat, 17 Jun 2006 10:11:11 -0600, "Ken Fox"
<morceaudemerdeThisMerdeGoes@hotmail.com > wrote:

> The
>water tube shown is the one I removed; it is distorted in shape a little bit
>which presumably relates to it having been used over a 10 year period. It
>was taking water out of the HX higher up in the HX than it should have due
>to the distortion in its shape.

I'm guessing the cold water enters at the top, so shortening the tube
will drop the temperature.

Micheal Teahan said that HX machines are desighned to be tweaked for
shot profiles in various ways; I guess one can do it on the Cimbali's
by adjusting the tube length and the boiler temp simultaneously.

Date: 17 Jun 2006 19:58:29
From: Ken Fox
Subject: Re: PIDing a Heat Exchanger, Part Trois

"jim schulman" <jim_schulman@ameritech.net > wrote in message
news:ema992h20naf92moe1ls58gmobb83shq2u@4ax.com...
> On Sat, 17 Jun 2006 10:11:11 -0600, "Ken Fox"
> <morceaudemerdeThisMerdeGoes@hotmail.com> wrote:
>
>> The
>>water tube shown is the one I removed; it is distorted in shape a little
>>bit
>>which presumably relates to it having been used over a 10 year period. It
>>was taking water out of the HX higher up in the HX than it should have due
>>to the distortion in its shape.
>
> I'm guessing the cold water enters at the top, so shortening the tube
> will drop the temperature.
>
> Micheal Teahan said that HX machines are desighned to be tweaked for
> shot profiles in various ways; I guess one can do it on the Cimbali's
> by adjusting the tube length and the boiler temp simultaneously.

Hi Jim,

I think that most HEX machines have some "secret" adjustments or repairs
that can be made to make them more temperature stable; I was only trying to
show THIS one from my own experience. What one would have to do with a
Nuova Simonelli or a Faema could be entirely different, but a discussion
with a tech knowledgeable in working with them might give clues.

Personally speaking, I think that too much is being made of absolute
temperature control in espresso machines and that most people would find
that they cannot taste the difference when brew temperature differences are
small, say under 2 degrees F. Nonetheless, if one IS interested in fine
temperature control, one might well find that it can be attained with the
equipment one already has sitting on the kitchen counter. It is also my
opinion that hacking old machines is way more fun than just "buying"
something that purports to be this solution in search of a problem.

My own opinion, for what it is worth, is that there is more to be gained
cheaply by playing around with pressure than with temperature. The delay
timer now installed on my rotary machine, which you have had the opportunity
to play around with, is an incredible upgrade available for less than $30
USD. Of course, Michael Teahan thought of THAT also, being as he was the
guy who told me to do the mod in the first place:-)

On to my total heresay for today; the easier way to get this is simply not
to upgrade from a vibe to a rotary machine in the first place; vibe machines
have slow pressure ramp ups inherent in their design, so no monkeying around
is required to get the sort of pressure profile one has to tweak a rotary
pump to deliver with such macchinations as installing delay timers:-)

ken

Date: 18 Jun 2006 08:23:04
From: Simpson
Subject: Re: PIDing a Heat Exchanger, Part Trois

In article <4fjq7vF1dohq6U1@individual.net >,
morceaudemerdeThisMerdeGoes@hotmail.com says...
snip
> My own opinion, for what it is worth, is that there is more to be gained
> cheaply by playing around with pressure than with temperature. The delay
> timer now installed on my rotary machine, which you have had the opportunity
> to play around with, is an incredible upgrade available for less than $30
> USD. Of course, Michael Teahan thought of THAT also, being as he was the
> guy who told me to do the mod in the first place:-)
snip

Ken, I don't know if Teahan thought of it or not, but I'd never heard of
him about six years ago when Al suggested it to me and Andy told me how
to do it. I've had this on several machines for years now. I still can't
decide if it matters, but it is fun to play with.

Ted
--
email me at:
tee en jay ess eye em pee ess oh en one-the-number (at) cee oh em cee a
ess tee (dot) en ee tee

ANY other email addie will probably mean I spam-killed your message
unread, by accident, really.

Date: 18 Jun 2006 08:23:20
From: Ken Fox
Subject: Re: PIDing a Heat Exchanger, Part Trois

"Simpson" <nospam@nospam.spam > wrote in message
news:MPG.1eff0fb616f88be98973c@newsgroups.comcast.net...
> In article <4fjq7vF1dohq6U1@individual.net>,
> morceaudemerdeThisMerdeGoes@hotmail.com says...
> snip
>> My own opinion, for what it is worth, is that there is more to be gained
>> cheaply by playing around with pressure than with temperature. The delay
>> timer now installed on my rotary machine, which you have had the
>> opportunity
>> to play around with, is an incredible upgrade available for less than $30
>> USD. Of course, Michael Teahan thought of THAT also, being as he was the
>> guy who told me to do the mod in the first place:-)
> snip
>
> Ken, I don't know if Teahan thought of it or not, but I'd never heard of
> him about six years ago when Al suggested it to me and Andy told me how
> to do it. I've had this on several machines for years now. I still can't
> decide if it matters, but it is fun to play with.
>
> Ted
> --

Ted,

I was referring to Michael T. as having suggested it to ME in THIS case.
However, Michael wrote a technical article about this in a journal
approximately 10 years ago, when he used to work designing espresso machines
for Brasilia.

Here's a link to a bio he posted on home-barista.com in January:

******
"I will be giving a technical presentation on European and American
standards for espresso machines and processes with Mark Crawford from ESI.
We will also be on the floor as exhibitors.

For those that don't know my background:

I started working with espresso machines as a distributor of equipment in
Portland in 1987. We designed out own line of espresso carts and doing
technical seminars for the US importer of Brasilia espresso machines.
Several coffee bars and restaurants later, I left Portland for Los Angeles
to eventually become the technical director Rosito Bisani (Brasilia). I
wrote for Fresh Cup Magazine delivering technical articles on espresso
machines for about a year and a half when the debate centered on the size of
boilers and how much steam a machine could deliver. I was against the
mainstream then, too.

I had a hand in designing many of the machines many prototypical espresso
machines for the U.S., but the heavy lifting was done by the engineers in
Italy. I designed and built prototype machines as 'proof of concept'
projects and shipped them to Italy for evaluation. Simple ideas like
automatic backflush programs came from my discussions with engineers at
Brasilia back in the 90's.

Most of my work through 2002 centered on automated espresso machine systems,
trying to develop hardware that was reliable and yet still deliver espresso
in keeping with traditional machines. It's possible, but difficult. The
importance of the operator, even in automated machines, is still more
important than manufacturers would like to admit.

After nearly 20 years, I work for no particular company and am able to say
whatever I wish. My only concern is what is in the cup and I don't have any
agenda on how to get there. The reality is that there are several. It is the
notion that there exists one machine, or one technology, that is superior to
all others (the one ring to rule them all??) that undermines the debate. Old
San Marco Levers in Naples make some of the best coffee on the planet. Maybe
it's because they hold the cups in boiling water before use. Interesting,
considering that most machines in the US don't even have cup warmers.

There are so many factors that play in the equation to make good espresso,
and though I have been chest high in the technology for most of my adult
life, I still believe it is the art that prevails. I am dismayed by baristas
who obsess about the technology instead of perfecting the process with the
technology they have. A bad mechanic always blames his tools, and thinks
that better tools are the solution.

Long enough? Seems I have to do this every so often.

Michael
_________________
Michael Teahan
Espresso Part Source"

**************

Whether Michael was the first person to think of this idea I do not know.

I'd be interested to know how you have executed the idea; in my case, I have
a pressure regulator set at about 3.5 bar on the mains pressure, which ends
up being the preinfusion pressure when the shot is begun but before the
delay timer tells the pump to turn on (6 second delay as I now have it set).
Jim and I tested this in our blind tested rotary with and without
(preinfusion) vs. vibe post a few months ago. Having now used it for a
couple of months I can say without doubt that using it reduces sink shots to
almost nothing with the rotary pump when I used to pitch maybe 10% of my
shots due to channelling (the bottomless PF of course makes this easy to
detect). It is doubtful in my opinion that a good shot, a "non-sink shot"
is demonstrably different with or without this sort of timed preinfusion.
It's worth nothing however that the Cimbali Junior rotary has a near
instantaneous pressure ramp up to preset values (9 bar in my case) without
the delay timer in place. Other machines with rotary pumps may have
different pressure profiles.

ken

Date: 18 Jun 2006 23:32:56
From: Andy Schecter
Subject: Re: PIDing a Heat Exchanger, Part Trois

Ken Fox wrote:
> Having now used it for a couple of months I can say without doubt that
> using it reduces sink shots to almost nothing

That's a shame, your sink must be suffering through a painful bout of caffeine
withdrawal.

--

-Andy S.

http://www.flickr.com/photos/andy_s/sets/
http://tinyurl.com/eh0x

Date: 18 Jun 2006 11:59:36
From: CoffeeGreek
Subject: Re: PIDing a Heat Exchanger, Part Trois

Andy Schecter wrote:
> 2. Teahan says the Italians seem to get better extractions using a temp
> profile that is a few degrees hotter at the beginning of the shot, then cools
> down. This is tough to achieve with a double boiler setup, but is relatively
> simple with a HX.

This could be an argument in favour of stable extraction temperatures
rather than against it. Since the coffee puck is at a low temperature,
the initial high-temperature water from the HX will cool down a bit as
it infuses the cold coffee grounds, while the water coming later in the
shot will stay hot. This could actually lead to a steady temperature
throughout the extraction. With a single boiler setup one will probably
get increasing temperature of extraction in the puck during the shot.
Schomer's graphs showing stable temperature were done, IIRC, with a
temp probe siting on top of the puck rather than buried inside it. The
latter setup would probably lead to various problems, like chaneling,
but maybe one could use a basket with a probe attached to the bottom.
This (coupled to a blindfolded Jim Schulman for taste comparisons)
could provide an answer.

George
? haven't we been through this before?

Date: 18 Jun 2006 10:53:13
From: daveb
Subject: Re: PIDing a Heat Exchanger, Part Trois

the short answer?

If it is NOT a cimbali Jr, well, then kenny does NOT like it!

easy.

Dave
www.hitechespresso.com
877 286 2833

Ken Fox wrote:
> "Marshall" <mrfuss@ihatespamearthlink.net> wrote in message
> news:8jh992phqskllikcs40baiki4ibil767ua@4ax.com...
> > > Ken,
> >
> > Your heroic efforts this past year to turn your heat exchanger into a
> > single boiler have helped push me to the following conclusion:
> > whatever the advantages of the HX in a commercial environment, they do
> > not translate to the long idle periods inherent in home use.
> >
> > Using them means playing "flush-and-pray," instead of having a
> > reliable temperature. At home, I think the HX is an economic
> > compromise (and a sensible one). But, if double boilers and heat
> > exchangers of the same quality were produced at the same price, I can
> > not imagine why any home user would buy an HX.
> >
> > I said this to Michael Teahan at lunch recently, and he did not argue
> > with me. Of course, that could simply have been because he was too
> > polite to tell me how stupid I am. But, I chose to take as a sign that
> > I had at least had an arguable case. :-)
> >
> > Marshall
>
> Marshall,
>
> If i were convinced that double boiler technology was as advanced today as
> you seem to think it is, I'd be in full agreement with you.
>
> Here's the condensed crystallized down set of issues to ponder in this
> discussion of, and choice of, machine types:
>
> (1) Are actually delivered temps as advertized --- yet to be proven
>
> (2) Are most people capable of tasting differences in brew temp small enough
> that it matters -- unclear
>
> (3) Are there maintenance, durability, and longeivity realities that would
> push one's choice in one direction or another -- arguably this favors old,
> reliable, easily fixed machines for whom there is a large number of dealers,
> and choice of knockoff vs. OEM parts.
>
> (4) Cognitive dissonance; is there a likelihood that after having plunked
> down beaucoup thousands of dollars that one will be inclined to justify such
> expenditure by convincing ones self of the wisdom of said purchase -- highly
> likely.
>
> (5) If one already owns a competent espresso machine, one has attained
> competent barista skills, and one uses high grade fresh coffee; what is the
> likelihood that if blindfolded one could sense obvious improvement when
> going from said former competent machine to a dual boiler machine? --
> unknown.
>
> ken

Date: 18 Jun 2006 10:51:59
From: daveb
Subject: Re: PIDing a Heat Exchanger, Part Trois

Date: 19 Jun 2006 03:36:59
From: daveb
Subject: Re: PIDing a Heat Exchanger, Part Trois

"Using them means playing "flush-and-pray," instead of having a
reliable temperature. At home, I think the HX is an economic
compromise (and a sensible one). But, if double boilers and heat
exchangers of the same quality were produced at the same price, I can
not imagine why any home user would buy an HX. "

Glad to see that the many deficits of an HX are now being acknowledged,
by more all the time.

IMO, an HX exists primarily to produce steam, not coffee.

I have a great idea for a money saving replacement for HX -- get a
single boiler machine -- one of the brand new PID silvias I sell, or
similar and a steamer on the side for about $75.00 voila! Solid
coffee BREW TEMPS and convenient steaming at HALF THE PRICE!

BTW -- no pressurestats!!

Dave
877 286 2833

Marshall wrote:
> On Sat, 17 Jun 2006 10:11:11 -0600, "Ken Fox"
> <morceaudemerdeThisMerdeGoes@hotmail.com> wrote:
>
> >This will be a brief, mostly graphic, illustration of a potential issue one
> >might encounter when PIDing a heat exchanger for purposes of shot
> >temperature stability. I've previously posted on the topic of PIDing my
> >Cimbali Junior machines and won't repeat the material that was previously
> >posted, other than to say that there were obvious differences in the shot
> >curve shapes obtained and inter-shot recovery times necessary observed in my
> >two machines, a 10+ year old vibratory pourover ("S") machine and a current
> >vintage Rotary ("D") machine.<snip>
>
> Ken,
>
> Your heroic efforts this past year to turn your heat exchanger into a
> single boiler have helped push me to the following conclusion:
> whatever the advantages of the HX in a commercial environment, they do
> not translate to the long idle periods inherent in home use.
>
> Using them means playing "flush-and-pray," instead of having a
> reliable temperature. At home, I think the HX is an economic
> compromise (and a sensible one). But, if double boilers and heat
> exchangers of the same quality were produced at the same price, I can
> not imagine why any home user would buy an HX.
>
> I said this to Michael Teahan at lunch recently, and he did not argue
> with me. Of course, that could simply have been because he was too
> polite to tell me how stupid I am. But, I chose to take as a sign that
> I had at least had an arguable case. :-)
>
> Marshall

Date: 18 Oct 2006 23:28:45
From: T. Swings
Subject: Re: PIDing a Heat Exchanger, Part Trois

"daveb" dave "crotchless" blane wrote in message

> "Using them means playing "flush-and-pray," instead of having a
> reliable temperature. At home, I think the HX is an economic
> compromise (and a sensible one). But, if double boilers and heat
> exchangers of the same quality were produced at the same price, I can
> not imagine why any home user would buy an HX. "
>
> Glad to see that the many deficits of an HX are now being acknowledged,
> by more all the time.
>
> IMO, an HX exists primarily to produce steam, not coffee.
>
> I have a great idea for a money saving replacement for HX -- get a
> single boiler machine -- one of the brand new PID silvias I sell, or
> similar and a steamer on the side for about $75.00 voila! Solid
> coffee BREW TEMPS and convenient steaming at HALF THE PRICE!
>
> BTW -- no pressurestats!!
>
> Dave
> 877 286 2833
>

first you snipe at the technical benefits of the bottomless p/f and now the
HX machine gets a bashing ............... is nothing safe??

Tarzan

Date: 19 Jun 2006 19:39:37
From: dadvocate
Subject: Re: PIDing a Heat Exchanger, Part Trois

daveb wrote:
> Glad to see that the many deficits of an HX are now being acknowledged,
> by more all the time.

Yep, Ken is providing the evidence step by step. Thanks Ken.

> IMO, an HX exists primarily to produce steam, not coffee.

No, it's to save money by requiring only a single heating element and
control system (at the expense of the kludgy plumbing complication plus
unstable temperatures).