Induction cooktops, temperature control questions

[Joseph Gwinn]

On May 30, 2019, Jasen Betts wrote
(in article <qcnq46$b3v$1@gonzo.revmaps.no-ip.org&gt:

On 2019-05-29, Joseph Gwinn<joegwinn@comcast.net> wrote:
On May 29, 2019, Jasen Betts wrote
(in article <qcllvt$m0m$2@gonzo.revmaps.no-ip.org&gt:

On 2019-05-28, Lasse Langwadt Christensen<langwadt@fonz.dk> wrote:
tirsdag den 28. maj 2019 kl. 20.30.19 UTC+2 skrev Jan Panteltje:
On a sunny day (Tue, 28 May 2019 10:58:48 -0700) it happened Joerg
news@analogconsultants.com> wrote in<gl5b6jFi0f5U1@mid.individual.net>:

Thanks, but not really. It is good to know that the aluminum heats up as
well. What I am more concerned about is whether, for example, instead of
1500W only 800W gets transferred because the coupling between coil and
lossy material becomes too loose. IOW the other 700W not being lost but
just not transferred and thus not taken out of the power outlet. All
minus the usual circuit losses, of course.

Nothing much seems to be transfered past the alu plate
Do I understand it right that you want a thick metal plate inside the
vessel?


From the same perspective at least some heating of your alu pot should
happen.
May even help to regulate the temperature better, warming up this alu
plate to 52 C took almost a minute!

But the same principle is used to screen IF coils in radios as I am
sure
you know.

Aluminum works quite well as a shield with real RF. Induction cookers
work in the 20-30kHz range AFAIK.

100 kHz here.
http://panteltje.com/pub/inductive_coupling_100kHz_500Vpp_IMG_6101.JPG

The wikipedia entry gives the formula for the eddy current induced power:
https://en.wikipedia.org/wiki/Eddy_current
I see f square for the power
also it is thickness square.

Anyways for a bit over 30$ you can get one from ebay and experiment,
car battery ?
This was on 15 V or so (2 x 7.5 V Meanwell in series, got those for
7euro50 each locally.

Why not use a thick steel plate under the vessel to heat it up?

then you have the same as a regular resistive heater and losses to the
surroundings

you could solder the steel plate to the base of the vessel

The temperature coefficients of Aluminum (21-24 ppm/F) and steel (11 to 12.5
ppm/F) are very different. Such a bi-metal assembly will likely warp and
tear itself apart.

I've got some stainless steel pots with aluminium heat spreaders, the
only failure mode I've seen is all the aluminium melting if it gets too hot.

The mating layer is very soft (pure) aluminum, which yields gracefully. The
stainless steel is thin, so the thick aluminum is able to keep it flat.

I have aluminum cored stainless steel cookware. All-Clad is the original
brand:<https://www.all-clad.com/About/history>. In this case the layers are
symmetric, and the aluminum welded to the steel is soft.

Anyway, there is some engineering to be done. Just soldering one metal to the
other is likely to cause problems.

..

For induction cooking you can't use a copper heat spreader because it
would reflect half of the energy. so these stainless steel pots have an
aluminium spreader and have a stainless skin on the bottom of that.

skin depth in 410 stainless is less than 0.1mm at 20KHz
skin depth in iron is even less.

There can be a copper core, but it must be after the magnetic stainless steel
layer that couples to the induction field. Then the reflection from the
copper (or pure aluminum) goes back into the magnetic stainless steel layer.

Joe Gwinn

 

[Joerg]

On 2019-05-30 08:11, Gerhard Hoffmann wrote:

Am 30.05.19 um 16:35 schrieb Joerg:

It would work but probably not efficiently because the water in the pan
underneath would constantly boil off. I'd have to keep filling with
pre-heated water.

Condensor (old car radiator), fan, water back to pan.



Pretty soon my brew place looks like the shop of Gary Gearloose

I wouldn't mind but I have to schlepp everything back and forth when
brewing.


As a byproduct to make some noodles today, I put an
still undrilled 2.5 mm aluminium 19" front panel between
the pot and the induction stove.

The stove switched completely off as if there was no
pot at all.

Dang. Thanks for the test. That pretty much ends my idea of using
induction cooktops.

... It saw nothing that took any energy from the field.

It wouldn't take energy away but could cause the coupling coefficient
between induction coil and pot bottom to become too low. So a large
chunk of the available isn't dissipated but just not being accepted. IOW
the power draw from the wall outlet would drop a lot. Which defeats my
purpose of trying to heat up beer brewing water faster than I can now.

Next up in 10 days is an American Amber Ale and a Belgian Witbier.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Gerhard Hoffmann]

Am 30.05.19 um 16:35 schrieb Joerg:

It would work but probably not efficiently because the water in the pan
underneath would constantly boil off. I'd have to keep filling with
pre-heated water.

Condensor (old car radiator), fan, water back to pan.



Pretty soon my brew place looks like the shop of Gary Gearloose

I wouldn't mind but I have to schlepp everything back and forth when
brewing.

As a byproduct to make some noodles today, I put an
still undrilled 2.5 mm aluminium 19" front panel between
the pot and the induction stove.

The stove switched completely off as if there was no
pot at all. It saw nothing that took any energy
from the field.

cheers,
Gerhard

 

[Joerg]

On 2019-05-29 18:53, Joseph Gwinn wrote:

On May 29, 2019, Joerg wrote
(in article <gl7msiF3204U1@mid.individual.net&gt:

On 2019-05-29 06:11, Joseph Gwinn wrote:
On May 28, 2019, Joerg wrote
(in article <gl51d5FftnrU1@mid.individual.net&gt:

On 2019-05-27 10:47, Joseph Gwinn wrote:
On May 27, 2019, Joerg wrote
(in article <gl2aggFsd7tU1@mid.individual.net&gt:

On 2019-05-26 12:40, Joseph Gwinn wrote:
On May 26, 2019, Joerg wrote
(in article <gl06onFeclbU1@mid.individual.net&gt:

On 2019-05-26 09:14, Joseph Gwinn wrote:

[...]

Attach thermostat plate to pot using silicon rubber adhesive.

If I had a material that would improve the coupling between electric
coil and the never 100% even pot bottom that would help a lot. Not for
the thermostats in the cooktops because they are already sufficiently
accurate but for heat transfer.

A sheet of silicon rubber is traditional. Such things are sold in kitchen
stores for various purposes.

Attaching the thermostat with silicon rubber adhesive serves to thermally
connect it to the pot.

This will prevent wind disturbances.

With my cheap Walmart burners I just set the thermostat slightly higher.
Worked every single time so far.

.
[snip]
How big is this monster pot? There are pots big enough to cook
missionaries.

It's got 16-1/2" or 42cm diameter. It could not be half an inch sh
rter
or it woudn't straddle my two cooktops.

How deep? I have some dutch ovens that large, but no stockpots.

Total volume is 13 gallons, it's pretty deep.

And 15-3/8" or 39cm deep, from the other email.

This is 108 pounds if full to the top.

I bought it for two reasons. Mainly to straddle two cooktops and then to
reduce the chance of a boil-over. Those are very messy in brewing.

It's filled with a little over 5-1/2 gallons of filtered water at the
beginning, then malt extract, dry malt extract and other stuff is added
but at least 1/2 gallon of water boils off as steam.

However, yes, the two cooktops underneath must be able to support a
combined weight of up to 50lbs. I was considering brewing a double-batch
a few times and then it would be almost 100lbs but so far haven't done
it. Mostly because the cooktops lack heating power.

Need a jib crane for loading and unloading as well.

Nah, due to lower back issues I always siphon it into the fermenter. It
sits on a foldable dolly for the trip to the temperature-controlled chamber.

.<https://www.northerntool.com/shop/tools/product_200651805_200651805

May exceed the budget, but the back is safe.

That would result in discussions with SWMBO. However, the siphoning
technique works very well and requires no lifting. When I remove the pot
for cleaning it's empty and light.

Ok, here I meant the cooktops, of course. The pot presents another
problem as mine isn't induction-suited.

Yep. Most of my pots aren´t either, but some do very well.

That's my issue, the brew kettle is not induction-suited so if I can't
make that compatible with a steel plate in there induction isn't going
to work. Mainly because it is tough and probably very expensive to fin

an induction-suited stainless pot with such a large diameter so it can
straddle two cooktops.

As has been discussed, one can sit the pot atop a piece of mild steel th
t
is heated by the induction heater. But that´s way more complex than an
electric coil, a thermocouple, and an industrial temperature controller.

It also nixes all the advantages of induction, and then some. You'd
incur roughly the same amount of contact losses plus the power losses in
the electronics of the induction driver. If a steel plate must be put
under the pot instead of inside I will stay with traditional electric
cooktops.

Yep. KISS. Fixed thermostat and coil heater, discussed earlier. Maybe 220
Vac, for sufficient power for a double batch. No electronics.

Oh, if I could get a large diameter 240 Vac heater at high power and
reasonable cost I'd be happy. It would need to be 3500W or more to yield
an advantage versus my current setup.

I bet you do not require anything like 3500 watts with good thermal contact
between pot and heater.

For heatup of brew water nothing beat kilowatts. Except more kilowatts.
But yes, good thermal contact would improve things. That isn't easy with
electric coil burners and an aluminum pot. Even with stainless pots it
isn't easy unless you have a $300+ version with a thick bottom.

By heater coil, I meant a coil intended for an electric stove; these are
readily available as spares in Home Depot et al for a few tens of dollars.
But use multiple coils connected in series, so they don´t get red hot and
burn the silicon rubber.

The problem is, this can only work if the contact is intimate and for
that you'd almost have to screw ech coil to the bottom of the pot in
several places.

The other thing that´s needed is a safety thermostat, that will trip and
cut the power if things get too hot. Or, design it to be self limiting,
stabilizing at a safe temperature even if the thermostat is stuck in the
heat-on position.

That is the least of worries.

Do not depend on your personal vigilance for such things. Unless you use a
one-legged
stool:<http://lateralscience.blogspot.com/2014/10/scottish-nitroglycerin-one-
legged-stools.html

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Gerhard Hoffmann]

Am 30.05.19 um 17:21 schrieb Joerg:

On 2019-05-30 08:11, Gerhard Hoffmann wrote:

As a byproduct to make some noodles today, I put an
still undrilled 2.5 mm aluminium 19" front panel between
the pot and the induction stove.

The stove switched completely off as if there was no
pot at all.


Dang. Thanks for the test. That pretty much ends my idea of using
induction cooktops.


 ... It saw nothing that took any energy from the field.


It wouldn't take energy away but could cause the coupling coefficient
between induction coil and pot bottom to become too low. So a large
chunk of the available isn't dissipated but just not being accepted. IOW
the power draw from the wall outlet would drop a lot. Which defeats my
purpose of trying to heat up beer brewing water faster than I can now.

You still could bolt the active area of an induction frying pan
to the bottom of your beer kettle, including thermal paste.
The thermal resistance might be quite small, just 2mm additional alu
way with a huge cross section.

 

[Jan Panteltje]

On a sunny day (Thu, 30 May 2019 17:11:32 +0200) it happened Gerhard Hoffmann
<dk4xp@arcor.de> wrote in <qcorr4$m48$1@solani.org>:

Am 30.05.19 um 16:35 schrieb Joerg:

It would work but probably not efficiently because the water in the pan
underneath would constantly boil off. I'd have to keep filling with
pre-heated water.

Condensor (old car radiator), fan, water back to pan.



Pretty soon my brew place looks like the shop of Gary Gearloose

I wouldn't mind but I have to schlepp everything back and forth when
brewing.


As a byproduct to make some noodles today, I put an
still undrilled 2.5 mm aluminium 19" front panel between
the pot and the induction stove.

The stove switched completely off as if there was no
pot at all. It saw nothing that took any energy
from the field.

cheers,
Gerhard

Some induction heaters have a metal sensor, a microswitch with magnet.
If the object is too far away, for example with some alu in between
that microswitch will not activate.

 

[Gerhard Hoffmann]

Am 30.05.19 um 19:21 schrieb Jan Panteltje:

Some induction heaters have a metal sensor, a microswitch with magnet.
If the object is too far away, for example with some alu in between
that microswitch will not activate.

A sheet of kitchen aluminium foil still works.
It even gets somewhat warm.

Putting the pot on some wooden chopsticks works also,
so it cannot be the distance.

 

[Joerg]

On 2019-05-30 10:02, Gerhard Hoffmann wrote:

Am 30.05.19 um 17:21 schrieb Joerg:
On 2019-05-30 08:11, Gerhard Hoffmann wrote:

[...]

... It saw nothing that took any energy from the field.


It wouldn't take energy away but could cause the coupling coefficient
between induction coil and pot bottom to become too low. So a large
chunk of the available isn't dissipated but just not being accepted.
IOW the power draw from the wall outlet would drop a lot. Which
defeats my purpose of trying to heat up beer brewing water faster than
I can now.

You still could bolt the active area of an induction frying pan
to the bottom of your beer kettle, including thermal paste.
The thermal resistance might be quite small, just 2mm additional alu
way with a huge cross section.

Drilling holes in my brew kettle? Nah. That big thing must be schlepped
into an unused shower for scrubbing and cleaning. Also, a leak in that
area would be really messy. Wort has a gooeiness similar to molasses.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Phil Hobbs]

On 5/30/19 10:35 AM, Joerg wrote:

On 2019-05-29 10:29, Jan Panteltje wrote:
On a sunny day (Wed, 29 May 2019 09:27:03 -0700) it happened Joerg
news@analogconsultants.com> wrote in <gl7q6hF3nt4U1@mid.individual.net>:

On 2019-05-29 09:07, Jan Panteltje wrote:
On a sunny day (Wed, 29 May 2019 08:30:33 -0700) it happened Joerg
news@analogconsultants.com> wrote in
gl7msiF3204U1@mid.individual.net>:

That's exactly what I have now and the cheap electric burners even
have
an adjustable thermostat. Which is needed because later I must avoid
boil-over and that requires a setting in the 210F region, adjustable
depending on wind and outside temperature.

I was wondering, I have a big steel induction cooking pan (thick
bottom),
just fill it with water and put the vessel in it?
Can never overheat (100C it boils), automatic temperature control!


It would work but probably not efficiently because the water in the pan
underneath would constantly boil off. I'd have to keep filling with
pre-heated water.

Condensor (old car radiator), fan, water back to pan.



Pretty soon my brew place looks like the shop of Gary Gearloose

_Gyro_ Gearloose, please. A gem among the second-tier comics.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Lasse Langwadt Christense]

torsdag den 30. maj 2019 kl. 22.55.28 UTC+2 skrev Phil Hobbs:

On 5/30/19 10:35 AM, Joerg wrote:
On 2019-05-29 10:29, Jan Panteltje wrote:
On a sunny day (Wed, 29 May 2019 09:27:03 -0700) it happened Joerg
news@analogconsultants.com> wrote in <gl7q6hF3nt4U1@mid.individual.net>:

On 2019-05-29 09:07, Jan Panteltje wrote:
On a sunny day (Wed, 29 May 2019 08:30:33 -0700) it happened Joerg
news@analogconsultants.com> wrote in
gl7msiF3204U1@mid.individual.net>:

That's exactly what I have now and the cheap electric burners even
have
an adjustable thermostat. Which is needed because later I must avoid
boil-over and that requires a setting in the 210F region, adjustable
depending on wind and outside temperature.

I was wondering, I have a big steel induction cooking pan (thick
bottom),
just fill it with water and put the vessel in it?
Can never overheat (100C it boils), automatic temperature control!


It would work but probably not efficiently because the water in the pan
underneath would constantly boil off. I'd have to keep filling with
pre-heated water.

Condensor (old car radiator), fan, water back to pan.



Pretty soon my brew place looks like the shop of Gary Gearloose


_Gyro_ Gearloose, please. A gem among the second-tier comics.

here he is called Georg

 

[Clifford Heath]

On 31/5/19 9:11 am, Joerg wrote:

On 2019-05-30 15:46, Lasse Langwadt Christensen wrote:
torsdag den 30. maj 2019 kl. 03.53.43 UTC+2 skrev Joseph Gwinn:
On May 29, 2019, Joerg wrote
(in article <gl7msiF3204U1@mid.individual.net&gt:

On 2019-05-29 06:11, Joseph Gwinn wrote:
On May 28, 2019, Joerg wrote
(in article <gl51d5FftnrU1@mid.individual.net&gt:

On 2019-05-27 10:47, Joseph Gwinn wrote:
On May 27, 2019, Joerg wrote
(in article <gl2aggFsd7tU1@mid.individual.net&gt:

On 2019-05-26 12:40, Joseph Gwinn wrote:
On May 26, 2019, Joerg wrote
(in article <gl06onFeclbU1@mid.individual.net&gt:


[...]


Ok, here I meant the cooktops, of course. The pot presents
another
problem as mine isn't induction-suited.

Yep. Most of my pots aren´t either, but some do very well.

That's my issue, the brew kettle is not induction-suited so if I
can't
make that compatible with a steel plate in there induction isn't
going
to work. Mainly because it is tough and probably very expensive
to fin

an induction-suited stainless pot with such a large diameter so
it can
straddle two cooktops.

As has been discussed, one can sit the pot atop a piece of mild
steel th
t
is heated by the induction heater. But that´s way more complex
than an
electric coil, a thermocouple, and an industrial temperature
controller.

It also nixes all the advantages of induction, and then some. You'd
incur roughly the same amount of contact losses plus the power
losses in
the electronics of the induction driver. If a steel plate must be put
under the pot instead of inside I will stay with traditional electric
cooktops.

Yep. KISS. Fixed thermostat and coil heater, discussed earlier.
Maybe 220
Vac, for sufficient power for a double batch. No electronics.

Oh, if I could get a large diameter 240 Vac heater at high power and
reasonable cost I'd be happy. It would need to be 3500W or more to
yield
an advantage versus my current setup.

I bet you do not require anything like 3500 watts with good thermal
contact
between pot and heater.

heating 50liters of water from say 5'C to 100'C is going to take

(50000*4,186*95) ~= 20MJ, at 3500W that is roughly 1.5 hour


5C? While we are missing our fair share of global warming it isn't quite
that cold out here

If I could get to 1.5h I'd jump for joy.

Does it have to be all-electric? You can get ginornous gas burners...

 

[Joerg]

On 2019-05-30 16:18, Lasse Langwadt Christensen wrote:

fredag den 31. maj 2019 kl. 01.11.08 UTC+2 skrev Joerg:
On 2019-05-30 15:46, Lasse Langwadt Christensen wrote:
torsdag den 30. maj 2019 kl. 03.53.43 UTC+2 skrev Joseph Gwinn:
On May 29, 2019, Joerg wrote
(in article <gl7msiF3204U1@mid.individual.net&gt:

On 2019-05-29 06:11, Joseph Gwinn wrote:
On May 28, 2019, Joerg wrote
(in article <gl51d5FftnrU1@mid.individual.net&gt:

On 2019-05-27 10:47, Joseph Gwinn wrote:
On May 27, 2019, Joerg wrote
(in article <gl2aggFsd7tU1@mid.individual.net&gt:

On 2019-05-26 12:40, Joseph Gwinn wrote:
On May 26, 2019, Joerg wrote
(in article <gl06onFeclbU1@mid.individual.net&gt:


[...]


Ok, here I meant the cooktops, of course. The pot presents another
problem as mine isn't induction-suited.

Yep. Most of my pots aren´t either, but some do very well.

That's my issue, the brew kettle is not induction-suited so if I can't
make that compatible with a steel plate in there induction isn't going
to work. Mainly because it is tough and probably very expensive to fin

an induction-suited stainless pot with such a large diameter so it can
straddle two cooktops.

As has been discussed, one can sit the pot atop a piece of mild steel th
t
is heated by the induction heater. But that´s way more complex than an
electric coil, a thermocouple, and an industrial temperature controller.

It also nixes all the advantages of induction, and then some. You'd
incur roughly the same amount of contact losses plus the power losses in
the electronics of the induction driver. If a steel plate must be put
under the pot instead of inside I will stay with traditional electric
cooktops.

Yep. KISS. Fixed thermostat and coil heater, discussed earlier. Maybe 220
Vac, for sufficient power for a double batch. No electronics.

Oh, if I could get a large diameter 240 Vac heater at high power and
reasonable cost I'd be happy. It would need to be 3500W or more to yield
an advantage versus my current setup.

I bet you do not require anything like 3500 watts with good thermal contact
between pot and heater.

heating 50liters of water from say 5'C to 100'C is going to take

(50000*4,186*95) ~= 20MJ, at 3500W that is roughly 1.5 hour


5C? While we are missing our fair share of global warming it isn't quite
that cold out here

I was guessing the water was straight from the tap

That's typically not so cold. Except maybe during a very hard winter.
Hwoever, to avoid such issues I fill up the pot before I brew and for
the 2nd batch in the afternoon I have plastic gallon bottles to fill the
kettle again. Brew equipment doesn't get much of a break here.

If I could get to 1.5h I'd jump for joy.

get a big water heater and preheat the water?

Can't do because it must be run through the big charcoal filter to
remove chlorine and stuff. I could plumb such a filter into the hot
water but that gets involved. Ours isn't that hot to begin with, you can
shower on hot-only without risking scalding. It would also nix the
evening pre-fill. When I get up in the morning I find a pre-filled brew
kettle, everything is wired up, radio thermostat at the ready, and I
just turn it all on. Then brushing teeth, breakfast, a shower, walking
the dogs.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Lasse Langwadt Christense]

fredag den 31. maj 2019 kl. 01.11.08 UTC+2 skrev Joerg:

On 2019-05-30 15:46, Lasse Langwadt Christensen wrote:
torsdag den 30. maj 2019 kl. 03.53.43 UTC+2 skrev Joseph Gwinn:
On May 29, 2019, Joerg wrote
(in article <gl7msiF3204U1@mid.individual.net&gt:

On 2019-05-29 06:11, Joseph Gwinn wrote:
On May 28, 2019, Joerg wrote
(in article <gl51d5FftnrU1@mid.individual.net&gt:

On 2019-05-27 10:47, Joseph Gwinn wrote:
On May 27, 2019, Joerg wrote
(in article <gl2aggFsd7tU1@mid.individual.net&gt:

On 2019-05-26 12:40, Joseph Gwinn wrote:
On May 26, 2019, Joerg wrote
(in article <gl06onFeclbU1@mid.individual.net&gt:


[...]


Ok, here I meant the cooktops, of course. The pot presents another
problem as mine isn't induction-suited.

Yep. Most of my pots aren´t either, but some do very well.

That's my issue, the brew kettle is not induction-suited so if I can't
make that compatible with a steel plate in there induction isn't going
to work. Mainly because it is tough and probably very expensive to fin

an induction-suited stainless pot with such a large diameter so it can
straddle two cooktops.

As has been discussed, one can sit the pot atop a piece of mild steel th
t
is heated by the induction heater. But that´s way more complex than an
electric coil, a thermocouple, and an industrial temperature controller.

It also nixes all the advantages of induction, and then some. You'd
incur roughly the same amount of contact losses plus the power losses in
the electronics of the induction driver. If a steel plate must be put
under the pot instead of inside I will stay with traditional electric
cooktops.

Yep. KISS. Fixed thermostat and coil heater, discussed earlier. Maybe 220
Vac, for sufficient power for a double batch. No electronics.

Oh, if I could get a large diameter 240 Vac heater at high power and
reasonable cost I'd be happy. It would need to be 3500W or more to yield
an advantage versus my current setup.

I bet you do not require anything like 3500 watts with good thermal contact
between pot and heater.

heating 50liters of water from say 5'C to 100'C is going to take

(50000*4,186*95) ~= 20MJ, at 3500W that is roughly 1.5 hour


5C? While we are missing our fair share of global warming it isn't quite
that cold out here

I was guessing the water was straight from the tap

If I could get to 1.5h I'd jump for joy.

get a big water heater and preheat the water?

 

[Joerg]

On 2019-05-30 15:46, Lasse Langwadt Christensen wrote:

torsdag den 30. maj 2019 kl. 03.53.43 UTC+2 skrev Joseph Gwinn:
On May 29, 2019, Joerg wrote
(in article <gl7msiF3204U1@mid.individual.net&gt:

On 2019-05-29 06:11, Joseph Gwinn wrote:
On May 28, 2019, Joerg wrote
(in article <gl51d5FftnrU1@mid.individual.net&gt:

On 2019-05-27 10:47, Joseph Gwinn wrote:
On May 27, 2019, Joerg wrote
(in article <gl2aggFsd7tU1@mid.individual.net&gt:

On 2019-05-26 12:40, Joseph Gwinn wrote:
On May 26, 2019, Joerg wrote
(in article <gl06onFeclbU1@mid.individual.net&gt:

[...]

Ok, here I meant the cooktops, of course. The pot presents another
problem as mine isn't induction-suited.

Yep. Most of my pots aren´t either, but some do very well.

That's my issue, the brew kettle is not induction-suited so if I can't
make that compatible with a steel plate in there induction isn't going
to work. Mainly because it is tough and probably very expensive to fin

an induction-suited stainless pot with such a large diameter so it can
straddle two cooktops.

As has been discussed, one can sit the pot atop a piece of mild steel th
t
is heated by the induction heater. But that´s way more complex than an
electric coil, a thermocouple, and an industrial temperature controller.

It also nixes all the advantages of induction, and then some. You'd
incur roughly the same amount of contact losses plus the power losses in
the electronics of the induction driver. If a steel plate must be put
under the pot instead of inside I will stay with traditional electric
cooktops.

Yep. KISS. Fixed thermostat and coil heater, discussed earlier. Maybe 220
Vac, for sufficient power for a double batch. No electronics.

Oh, if I could get a large diameter 240 Vac heater at high power and
reasonable cost I'd be happy. It would need to be 3500W or more to yield
an advantage versus my current setup.

I bet you do not require anything like 3500 watts with good thermal contact
between pot and heater.

heating 50liters of water from say 5'C to 100'C is going to take

(50000*4,186*95) ~= 20MJ, at 3500W that is roughly 1.5 hour

5C? While we are missing our fair share of global warming it isn't quite
that cold out here

If I could get to 1.5h I'd jump for joy.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 2019-05-30 15:53, Lasse Langwadt Christensen wrote:

torsdag den 30. maj 2019 kl. 03.09.35 UTC+2 skrev Clifford Heath:
On 30/5/19 1:30 am, Joerg wrote:
On 2019-05-29 06:11, Joseph Gwinn wrote:
Yep. KISS. Fixed thermostat and coil heater, discussed earlier.
Maybe 220 Vac, for sufficient power for a double batch. No
electronics.
Oh, if I could get a large diameter 240W heater at high power
and reasonable cost I'd be happy. It would need to be 3500W or
more to yield an advantage versus my current setup.

What about a replacement heating coil for a 240V electric range?
There'd have to be some available at 3500W, I think?

I suspect it gets real hard to effective transfer that much power
through conduction with out things getting red hot, probably why the
high powers are only easily available as induction

It's a matter of diameter. The 1kW burners do become red hot in sections
of the coil but they are small. You just need a larger one to do 3500W.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 2019-05-30 15:39, Lasse Langwadt Christensen wrote:

torsdag den 30. maj 2019 kl. 22.55.28 UTC+2 skrev Phil Hobbs:
On 5/30/19 10:35 AM, Joerg wrote:
On 2019-05-29 10:29, Jan Panteltje wrote:
On a sunny day (Wed, 29 May 2019 09:27:03 -0700) it happened Joerg
news@analogconsultants.com> wrote in <gl7q6hF3nt4U1@mid.individual.net>:

On 2019-05-29 09:07, Jan Panteltje wrote:
On a sunny day (Wed, 29 May 2019 08:30:33 -0700) it happened Joerg
news@analogconsultants.com> wrote in
gl7msiF3204U1@mid.individual.net>:

That's exactly what I have now and the cheap electric burners even
have
an adjustable thermostat. Which is needed because later I must avoid
boil-over and that requires a setting in the 210F region, adjustable
depending on wind and outside temperature.

I was wondering, I have a big steel induction cooking pan (thick
bottom),
just fill it with water and put the vessel in it?
Can never overheat (100C it boils), automatic temperature control!


It would work but probably not efficiently because the water in the pan
underneath would constantly boil off. I'd have to keep filling with
pre-heated water.

Condensor (old car radiator), fan, water back to pan.



Pretty soon my brew place looks like the shop of Gary Gearloose


_Gyro_ Gearloose, please. A gem among the second-tier comics.


here he is called Georg

In Germany "Daniel Duesentrieb", referring to the old term
Duesentriebwerk for jet engine. Whenever a new comic book about them
came out during my childhood I had to have it.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Lasse Langwadt Christense]

torsdag den 30. maj 2019 kl. 03.09.35 UTC+2 skrev Clifford Heath:

On 30/5/19 1:30 am, Joerg wrote:
On 2019-05-29 06:11, Joseph Gwinn wrote:
Yep. KISS. Fixed thermostat and coil heater, discussed earlier. Maybe 220
Vac, for sufficient power for a double batch. No electronics.
Oh, if I could get a large diameter 240W heater at high power and
reasonable cost I'd be happy. It would need to be 3500W or more to yield
an advantage versus my current setup.

What about a replacement heating coil for a 240V electric range?
There'd have to be some available at 3500W, I think?

I suspect it gets real hard to effective transfer that much power through conduction with out things getting red hot, probably why the high powers
are only easily available as induction

 

[Lasse Langwadt Christense]

torsdag den 30. maj 2019 kl. 03.53.43 UTC+2 skrev Joseph Gwinn:

On May 29, 2019, Joerg wrote
(in article <gl7msiF3204U1@mid.individual.net&gt:

On 2019-05-29 06:11, Joseph Gwinn wrote:
On May 28, 2019, Joerg wrote
(in article <gl51d5FftnrU1@mid.individual.net&gt:

On 2019-05-27 10:47, Joseph Gwinn wrote:
On May 27, 2019, Joerg wrote
(in article <gl2aggFsd7tU1@mid.individual.net&gt:

On 2019-05-26 12:40, Joseph Gwinn wrote:
On May 26, 2019, Joerg wrote
(in article <gl06onFeclbU1@mid.individual.net&gt:

On 2019-05-26 09:14, Joseph Gwinn wrote:

[...]

What I did in the old days, when electric-coil hobs had four setting

(including off), was to use such a hob set to full power, but driven
fro

a
variac. Now days, one would use a solid-state variable power control
intended
for a hot tub.

A big dimmer would suffice. With electric burners it's not needed
because even the cheap ones have nice analog controls. That's still no

as good as a thermostat though because these cheap cooktops really
regulate the coil temperature and thus (indirectly) the temperature at
the bottom of the pot. On cold and windy days outside I have to set it
slightly higher and it still works.

It sounds like what you need is acommon industrial temperature controlle

plus a 12-volt DC relay to turn the hob AC power on and off, replacing t
e
internal coil-temp thermostat. Attach thermocouple to bottom of pot away
from
the heating coils, in a bit of aluminum pressed up against the bottom of
the
pot. Or have it dip into the mash fluid.

Here is a suitable unit. I buy stuff from Automation Direct, and it all
has
worked.

.<https://www.automationdirect.com/adc/shopping/catalog/process_control_
a
-
_measurement/temperature_-z-
_process_controllers/solo_basic_temperature_controllers

The unit in question is a "SOLO Basic Temperature Controller", and costs
$40 (not including power relay and thermocouple).

I already have this controller:

https://www.amazon.com/dp/B00V4TJR00

Currently used whenever I brew too much and need to use our old
downstairs fridge as a fermentation chamber. You can even set the
hysteresis on these controllers. For some reason mine came with a UK
outlet so I use my homemade UK travel adapter.

For brewing a simple bi-metal thermostat suffices, you can get those to
hold to within +/-2F.

If it´s always 156 F, one can buy fixed-temperature thermostats plus an AC
power relay. Attach thermostat to center bottom of the pot and a concentric
ring heater coil also to the pot. Use thermostat to control ring heater.

That's exactly what I have now and the cheap electric burners even have
an adjustable thermostat. Which is needed because later I must avoid
boil-over and that requires a setting in the 210F region, adjustable
depending on wind and outside temperature.

Attach thermostat plate to pot using silicon rubber adhesive.

If I had a material that would improve the coupling between electric
coil and the never 100% even pot bottom that would help a lot. Not for
the thermostats in the cooktops because they are already sufficiently
accurate but for heat transfer.

A sheet of silicon rubber is traditional. Such things are sold in kitchen
stores for various purposes.

Attaching the thermostat with silicon rubber adhesive serves to thermally
connect it to the pot.

This will prevent wind disturbances.



.
[snip]
How big is this monster pot? There are pots big enough to cook
missionaries.

It's got 16-1/2" or 42cm diameter. It could not be half an inch sh
rter
or it woudn't straddle my two cooktops.

How deep? I have some dutch ovens that large, but no stockpots.

Total volume is 13 gallons, it's pretty deep.

And 15-3/8" or 39cm deep, from the other email.

This is 108 pounds if full to the top.

I bought it for two reasons. Mainly to straddle two cooktops and then to
reduce the chance of a boil-over. Those are very messy in brewing.

It's filled with a little over 5-1/2 gallons of filtered water at the
beginning, then malt extract, dry malt extract and other stuff is added
but at least 1/2 gallon of water boils off as steam.

However, yes, the two cooktops underneath must be able to support a
combined weight of up to 50lbs. I was considering brewing a double-batch
a few times and then it would be almost 100lbs but so far haven't done
it. Mostly because the cooktops lack heating power.

Need a jib crane for loading and unloading as well.

Nah, due to lower back issues I always siphon it into the fermenter. It
sits on a foldable dolly for the trip to the temperature-controlled chamber.

.<https://www.northerntool.com/shop/tools/product_200651805_200651805

May exceed the budget, but the back is safe.

[snip]
Ok, here I meant the cooktops, of course. The pot presents another
problem as mine isn't induction-suited.

Yep. Most of my pots aren´t either, but some do very well.

That's my issue, the brew kettle is not induction-suited so if I can't
make that compatible with a steel plate in there induction isn't going
to work. Mainly because it is tough and probably very expensive to fin

an induction-suited stainless pot with such a large diameter so it can
straddle two cooktops.

As has been discussed, one can sit the pot atop a piece of mild steel th
t
is heated by the induction heater. But that´s way more complex than an
electric coil, a thermocouple, and an industrial temperature controller.

It also nixes all the advantages of induction, and then some. You'd
incur roughly the same amount of contact losses plus the power losses in
the electronics of the induction driver. If a steel plate must be put
under the pot instead of inside I will stay with traditional electric
cooktops.

Yep. KISS. Fixed thermostat and coil heater, discussed earlier. Maybe 220
Vac, for sufficient power for a double batch. No electronics.

Oh, if I could get a large diameter 240 Vac heater at high power and
reasonable cost I'd be happy. It would need to be 3500W or more to yield
an advantage versus my current setup.

I bet you do not require anything like 3500 watts with good thermal contact
between pot and heater.

heating 50liters of water from say 5'C to 100'C is going to take

(50000*4,186*95) ~= 20MJ, at 3500W that is roughly 1.5 hour

 

[Joerg]

On 2019-05-30 16:28, Clifford Heath wrote:

On 31/5/19 9:11 am, Joerg wrote:
On 2019-05-30 15:46, Lasse Langwadt Christensen wrote:
torsdag den 30. maj 2019 kl. 03.53.43 UTC+2 skrev Joseph Gwinn:
On May 29, 2019, Joerg wrote
(in article <gl7msiF3204U1@mid.individual.net&gt:

On 2019-05-29 06:11, Joseph Gwinn wrote:
On May 28, 2019, Joerg wrote
(in article <gl51d5FftnrU1@mid.individual.net&gt:

On 2019-05-27 10:47, Joseph Gwinn wrote:
On May 27, 2019, Joerg wrote
(in article <gl2aggFsd7tU1@mid.individual.net&gt:

On 2019-05-26 12:40, Joseph Gwinn wrote:
On May 26, 2019, Joerg wrote
(in article <gl06onFeclbU1@mid.individual.net&gt:


[...]


Ok, here I meant the cooktops, of course. The pot presents
another
problem as mine isn't induction-suited.

Yep. Most of my pots aren´t either, but some do very well.

That's my issue, the brew kettle is not induction-suited so if
I can't
make that compatible with a steel plate in there induction
isn't going
to work. Mainly because it is tough and probably very expensive
to fin

an induction-suited stainless pot with such a large diameter so
it can
straddle two cooktops.

As has been discussed, one can sit the pot atop a piece of mild
steel th
t
is heated by the induction heater. But that´s way more complex
than an
electric coil, a thermocouple, and an industrial temperature
controller.

It also nixes all the advantages of induction, and then some. You'd
incur roughly the same amount of contact losses plus the power
losses in
the electronics of the induction driver. If a steel plate must be
put
under the pot instead of inside I will stay with traditional
electric
cooktops.

Yep. KISS. Fixed thermostat and coil heater, discussed earlier.
Maybe 220
Vac, for sufficient power for a double batch. No electronics.

Oh, if I could get a large diameter 240 Vac heater at high power and
reasonable cost I'd be happy. It would need to be 3500W or more to
yield
an advantage versus my current setup.

I bet you do not require anything like 3500 watts with good thermal
contact
between pot and heater.

heating 50liters of water from say 5'C to 100'C is going to take

(50000*4,186*95) ~= 20MJ, at 3500W that is roughly 1.5 hour


5C? While we are missing our fair share of global warming it isn't
quite that cold out here

If I could get to 1.5h I'd jump for joy.

Does it have to be all-electric? You can get ginornous gas burners...

I know. However, the downstairs can't easily be vented safely so CO is
an issue. Also, then you have to always store two large gas bottles.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Lasse Langwadt Christense]

fredag den 31. maj 2019 kl. 01.29.07 UTC+2 skrev Joerg:

On 2019-05-30 16:18, Lasse Langwadt Christensen wrote:
fredag den 31. maj 2019 kl. 01.11.08 UTC+2 skrev Joerg:
On 2019-05-30 15:46, Lasse Langwadt Christensen wrote:
torsdag den 30. maj 2019 kl. 03.53.43 UTC+2 skrev Joseph Gwinn:
On May 29, 2019, Joerg wrote
(in article <gl7msiF3204U1@mid.individual.net&gt:

On 2019-05-29 06:11, Joseph Gwinn wrote:
On May 28, 2019, Joerg wrote
(in article <gl51d5FftnrU1@mid.individual.net&gt:

On 2019-05-27 10:47, Joseph Gwinn wrote:
On May 27, 2019, Joerg wrote
(in article <gl2aggFsd7tU1@mid.individual.net&gt:

On 2019-05-26 12:40, Joseph Gwinn wrote:
On May 26, 2019, Joerg wrote
(in article <gl06onFeclbU1@mid.individual.net&gt:


[...]


Ok, here I meant the cooktops, of course. The pot presents another
problem as mine isn't induction-suited.

Yep. Most of my pots aren´t either, but some do very well..

That's my issue, the brew kettle is not induction-suited so if I can't
make that compatible with a steel plate in there induction isn't going
to work. Mainly because it is tough and probably very expensive to fin

an induction-suited stainless pot with such a large diameter so it can
straddle two cooktops.

As has been discussed, one can sit the pot atop a piece of mild steel th
t
is heated by the induction heater. But that´s way more complex than an
electric coil, a thermocouple, and an industrial temperature controller.

It also nixes all the advantages of induction, and then some. You'd
incur roughly the same amount of contact losses plus the power losses in
the electronics of the induction driver. If a steel plate must be put
under the pot instead of inside I will stay with traditional electric
cooktops.

Yep. KISS. Fixed thermostat and coil heater, discussed earlier. Maybe 220
Vac, for sufficient power for a double batch. No electronics.

Oh, if I could get a large diameter 240 Vac heater at high power and
reasonable cost I'd be happy. It would need to be 3500W or more to yield
an advantage versus my current setup.

I bet you do not require anything like 3500 watts with good thermal contact
between pot and heater.

heating 50liters of water from say 5'C to 100'C is going to take

(50000*4,186*95) ~= 20MJ, at 3500W that is roughly 1.5 hour


5C? While we are missing our fair share of global warming it isn't quite
that cold out here

I was guessing the water was straight from the tap


That's typically not so cold. Except maybe during a very hard winter.
Hwoever, to avoid such issues I fill up the pot before I brew and for
the 2nd batch in the afternoon I have plastic gallon bottles to fill the
kettle again. Brew equipment doesn't get much of a break here.


If I could get to 1.5h I'd jump for joy.

get a big water heater and preheat the water?


Can't do because it must be run through the big charcoal filter to
remove chlorine and stuff. I could plumb such a filter into the hot
water but that gets involved. Ours isn't that hot to begin with, you can
shower on hot-only without risking scalding. It would also nix the
evening pre-fill. When I get up in the morning I find a pre-filled brew
kettle, everything is wired up, radio thermostat at the ready, and I
just turn it all on. Then brushing teeth, breakfast, a shower, walking
the dogs.

I was thinking an extra water heater just for the brewing, you can get
tankless ones with 10s of kW