Induction cooktops, temperature control questions

[Joerg]

On 2019-05-24 09:30, Lasse Langwadt Christensen wrote:

fredag den 24. maj 2019 kl. 16.43.51 UTC+2 skrev Joerg:
On 2019-05-23 17:27, Winfield Hill wrote:
Joerg wrote...

John Larkin wrote:

Inductive heating must be less efficient than resistive. Resistive
is best if you can make a good thermal connection to your kettle.

From what I heard and read so far inductiove is more efficient.
Power loss in the bridge FETs and coil is so low that a small
fan suffices but there is almost no more transfer loss.

Yes, resistive heating sends lots of heat to other places.


It does, although when I cup my hands around the bottom of the pot it's
not all that much. The main thing is that one can buy 1800W induction
cooktops but the small coil burners are never much more than 1000W. I
also can't goose those with a step-up transformer because at full bore
there aleady is a noticable red glow.

The other thing is the thermal coupling. It takes some finagling with
folded paper snippets used as shims to get the coil of both burners to
snug the bottom of the pot. I marked them so I know where they go for
the "initial coarse alignment".


add some help, https://www.ebay.com/itm/162315122285

Ah, excellent idea! Of course, then I'd have to recalculate to
centigrade

Thanks.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 2019-05-24 08:32, John Larkin wrote:

On Fri, 24 May 2019 07:59:15 -0700, Joerg <news@analogconsultants.com
wrote:

On 2019-05-23 22:24, Mikko OH2HVJ wrote:
Joerg <news@analogconsultants.com> writes:

Thinking about induction cooktops for beer brewing because the two 1kW
..
However ... for reasons that I'll never understand the temperature can
only be set in 40F increments and very occasionally there are units
with 10F steps. Way too coarse for brewing. Even for sous-vide chefs
that isn't good enough. I am talking about the usual $50 price range,
not $1k restaurant grade. The thermostats on my $12 Walmart cooktops
are nicely analog-controlled so I can set them exactly where needed.

How is the temperature measured on those ? It might be the difficulty of
doing accurate temperature sensing with the ceramic plate in
between. IIRC some InGaAs photodiodes list this as one application in
their datasheets, but I would not expect to see those in cheaper units!


From what I saw so far in tear-downs there is a thermistor wadded into
something, right under the ceramic plate in the middle of the coil.
Probably a PTC or NTC resistor.

It may not be too accurate but brewers soon get a good feel for
correction factors. The bi-metal thermostats on my cheap coil burners
should theoretically be much less accurate because they only sense the
temperature at the end of the heating coil, not the surface. Yet I was
able to mark them so I can set them to 156F (for grain steeping) and
later shortly under max but outside the numbered range for "boil-over
avoidance". Holds it to within +/-2F. Inside the house it is always
accurate, outside during summer I have to apply a minor correction
factor if it is under 70F, windy or foggy. After a few dozen brews
outside one knows. So while the grains of the first batch of the day are
steeping I can take a shower and brush my teeth, knowing that the
temperature is going to be fine. It always was.


Bricks, then an aluminum plate with big MIL resistors bolted to the
bottom. Gap-pad stuff stuck to the top, with the pot sitting on that.
Dunk a thermocouple into the brew. Design a controller or buy a cheap
Omega equivalent.

I assume with gap-pad you mean the stuff used to heatsink SMT
transistors et cetera to a nearby chassis panel. I wonder if that could
take the heat of a red-glowing spiral burner section. Then I could just
use my cooktops but have better heat coupling.

Lasse's idea of a heat jacket is a good one. I'd have to find a 3rd 120V
circuit nearby though.

Send me a case in gratitude.

I'd have to bring that, it doesn't travel well or would the need a week
of rest for the yeast residue to flocculate back down.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joseph Gwinn]

On May 24, 2019, Joerg wrote
(in article <gkqf5pF72a9U1@mid.individual.net&gt:

On 2019-05-23 22:24, Mikko OH2HVJ wrote:
Joerg <news@analogconsultants.com> writes:

Thinking about induction cooktops for beer brewing because the two 1kW
..
However ... for reasons that I'll never understand the temperature can
only be set in 40F increments and very occasionally there are units
with 10F steps. Way too coarse for brewing. Even for sous-vide chefs
that isn't good enough. I am talking about the usual $50 price range,
not $1k restaurant grade. The thermostats on my $12 Walmart cooktops
are nicely analog-controlled so I can set them exactly where needed.

How is the temperature measured on those ? It might be the difficulty of
doing accurate temperature sensing with the ceramic plate in
between. IIRC some InGaAs photodiodes list this as one application in
their datasheets, but I would not expect to see those in cheaper units!

From what I saw so far in tear-downs there is a thermistor wadded into
something, right under the ceramic plate in the middle of the coil.
Probably a PTC or NTC resistor.

I´ve read some patents. That is exactly how it works. The heat is provided
in a ring, and measured in the center, well away from the heat path. Sort of
like a 4-wire resistance measurement.

I did come across one reasonably priced induction hob that claims to have
100-step power control. I bought and tested one of their models (PIC Gold),
and the 100-step claim is plausible. It is certainly far more than ten
levels, which is maddeningly coarse even for ordinary cooking.

Confusingly, they talk of four power levels: these are selectable maximum
power draw levels, so one can use the same hob in a house (full 1800 watts),
or on a RV or a boat (far less is available), without blowing breakers.

The induction hob in question is called NuWave and is made by Hearthwave, Inc
in Libertyville, IL 60048. NuWave LLC seems to have been stood up for this
business area.

PIC Pro ($180) is 1800 watts max:
..<https://nuwavenow.com/NuWavePIC?ref_version=DIRECT7&TM=1558731410289>

..<https://nuwavenow.com/Patent>

Their patents are useful for somewhat more technical detail than user-manual
level, but are also a bit confusing.

NuWave induction cookware gets very bad reviews. European cookware rated for
induction works well.

Joe Gwinn

 

[Joerg]

On 2019-05-24 14:12, Joseph Gwinn wrote:

On May 24, 2019, Joerg wrote
(in article <gkqf5pF72a9U1@mid.individual.net&gt:

On 2019-05-23 22:24, Mikko OH2HVJ wrote:
Joerg <news@analogconsultants.com> writes:

Thinking about induction cooktops for beer brewing because the two 1kW
..
However ... for reasons that I'll never understand the temperature can
only be set in 40F increments and very occasionally there are units
with 10F steps. Way too coarse for brewing. Even for sous-vide chefs
that isn't good enough. I am talking about the usual $50 price range,
not $1k restaurant grade. The thermostats on my $12 Walmart cooktops
are nicely analog-controlled so I can set them exactly where needed.

How is the temperature measured on those ? It might be the difficulty of
doing accurate temperature sensing with the ceramic plate in
between. IIRC some InGaAs photodiodes list this as one application in
their datasheets, but I would not expect to see those in cheaper units!

From what I saw so far in tear-downs there is a thermistor wadded into
something, right under the ceramic plate in the middle of the coil.
Probably a PTC or NTC resistor.

I´ve read some patents. That is exactly how it works. The heat is provided
in a ring, and measured in the center, well away from the heat path. Sort of
like a 4-wire resistance measurement.

I did come across one reasonably priced induction hob that claims to have
100-step power control. I bought and tested one of their models (PIC Gold),
and the 100-step claim is plausible. It is certainly far more than ten
levels, which is maddeningly coarse even for ordinary cooking.

Confusingly, they talk of four power levels: these are selectable maximum
power draw levels, so one can use the same hob in a house (full 1800 watts),
or on a RV or a boat (far less is available), without blowing breakers.

The power levels are nice, many have six or more. This one has 10 settings:

https://www.walmart.com/ip/Midea-1500W-Induction-Cooktop-Cooker-With-Stainless-Steel-Pot-Table-Hotpot/405872121

There are two things that manufacturers generally do wrong. They do not
provide power levels in the 100W range so you can't easily use the
cooktops for slow-cooking. Then the temperature control granularity is
way too coarse which makes them less useful for brewing, pasteurization
and many industrial processes. Both could easily be provided at zero
extra cost.

The induction hob in question is called NuWave and is made by Hearthwave, Inc
in Libertyville, IL 60048. NuWave LLC seems to have been stood up for this
business area.

PIC Pro ($180) is 1800 watts max:
.<https://nuwavenow.com/NuWavePIC?ref_version=DIRECT7&TM=1558731410289

.<https://nuwavenow.com/Patent

Their patents are useful for somewhat more technical detail than user-manual
level, but are also a bit confusing.

Their temp control happens at 10F granularity which unfortunately is too
coarse for brewing.

Derek Decker in a brewing NG suggested an interesting cooktop:

https://www.tastyonetop.com/

I'd have to inquire but it seems this might be controllable in 1F
increments and even has an external sensor. The alternative would be to
hack a regular induction top and have an external loop. With some
hysteresis I could hang a FET opto-coupler across the built-in center
thermistor and fool it into believing the temerature has been exceeded,
which woud turn it off until I let go.

That still leaves the question how far the steel plate could be from the
cooktop. Jan's experiment was encouraging, he held the pan about half an
inch away in the air and it still cooked an egg. He forgot the bacon
though ...

NuWave induction cookware gets very bad reviews. ...

We've had a sort of radiant heat cooker here from a friend. It had a big
pot and the heater unit was in a thick lid. Wasn't impressed. The
quality was ok, just the general idea of cooking that way wasn't, IMHO.

... European cookware rated for induction works well.

I have relatives there so someone could bring it when visiting. It's not
a slam dunk though because most are rated 230V and our two-phase easily
goes to 255V for hours. I could use a 24V step-down but that starts to
get old.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 2019-05-24 14:59, John Larkin wrote:

On Fri, 24 May 2019 11:43:06 -0700, Joerg <news@analogconsultants.com
wrote:

On 2019-05-24 08:32, John Larkin wrote:
On Fri, 24 May 2019 07:59:15 -0700, Joerg <news@analogconsultants.com
wrote:

On 2019-05-23 22:24, Mikko OH2HVJ wrote:
Joerg <news@analogconsultants.com> writes:

Thinking about induction cooktops for beer brewing because the two 1kW
..
However ... for reasons that I'll never understand the temperature can
only be set in 40F increments and very occasionally there are units
with 10F steps. Way too coarse for brewing. Even for sous-vide chefs
that isn't good enough. I am talking about the usual $50 price range,
not $1k restaurant grade. The thermostats on my $12 Walmart cooktops
are nicely analog-controlled so I can set them exactly where needed.

How is the temperature measured on those ? It might be the difficulty of
doing accurate temperature sensing with the ceramic plate in
between. IIRC some InGaAs photodiodes list this as one application in
their datasheets, but I would not expect to see those in cheaper units!


From what I saw so far in tear-downs there is a thermistor wadded into
something, right under the ceramic plate in the middle of the coil.
Probably a PTC or NTC resistor.

It may not be too accurate but brewers soon get a good feel for
correction factors. The bi-metal thermostats on my cheap coil burners
should theoretically be much less accurate because they only sense the
temperature at the end of the heating coil, not the surface. Yet I was
able to mark them so I can set them to 156F (for grain steeping) and
later shortly under max but outside the numbered range for "boil-over
avoidance". Holds it to within +/-2F. Inside the house it is always
accurate, outside during summer I have to apply a minor correction
factor if it is under 70F, windy or foggy. After a few dozen brews
outside one knows. So while the grains of the first batch of the day are
steeping I can take a shower and brush my teeth, knowing that the
temperature is going to be fine. It always was.


Bricks, then an aluminum plate with big MIL resistors bolted to the
bottom. Gap-pad stuff stuck to the top, with the pot sitting on that.
Dunk a thermocouple into the brew. Design a controller or buy a cheap
Omega equivalent.


I assume with gap-pad you mean the stuff used to heatsink SMT
transistors et cetera to a nearby chassis panel. I wonder if that could
take the heat of a red-glowing spiral burner section. Then I could just
use my cooktops but have better heat coupling.

Lasse's idea of a heat jacket is a good one. I'd have to find a 3rd 120V
circuit nearby though.

I use a soft, gummy silicone stuff from 3G Shielding, about 6 w/mK,
pretty good heat conductor. The data sheet says 160C max.

That would be greatly exceeded at the spots where the coil glows red.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[John Larkin]

On Fri, 24 May 2019 11:43:06 -0700, Joerg <news@analogconsultants.com>
wrote:

On 2019-05-24 08:32, John Larkin wrote:
On Fri, 24 May 2019 07:59:15 -0700, Joerg <news@analogconsultants.com
wrote:

On 2019-05-23 22:24, Mikko OH2HVJ wrote:
Joerg <news@analogconsultants.com> writes:

Thinking about induction cooktops for beer brewing because the two 1kW
..
However ... for reasons that I'll never understand the temperature can
only be set in 40F increments and very occasionally there are units
with 10F steps. Way too coarse for brewing. Even for sous-vide chefs
that isn't good enough. I am talking about the usual $50 price range,
not $1k restaurant grade. The thermostats on my $12 Walmart cooktops
are nicely analog-controlled so I can set them exactly where needed.

How is the temperature measured on those ? It might be the difficulty of
doing accurate temperature sensing with the ceramic plate in
between. IIRC some InGaAs photodiodes list this as one application in
their datasheets, but I would not expect to see those in cheaper units!


From what I saw so far in tear-downs there is a thermistor wadded into
something, right under the ceramic plate in the middle of the coil.
Probably a PTC or NTC resistor.

It may not be too accurate but brewers soon get a good feel for
correction factors. The bi-metal thermostats on my cheap coil burners
should theoretically be much less accurate because they only sense the
temperature at the end of the heating coil, not the surface. Yet I was
able to mark them so I can set them to 156F (for grain steeping) and
later shortly under max but outside the numbered range for "boil-over
avoidance". Holds it to within +/-2F. Inside the house it is always
accurate, outside during summer I have to apply a minor correction
factor if it is under 70F, windy or foggy. After a few dozen brews
outside one knows. So while the grains of the first batch of the day are
steeping I can take a shower and brush my teeth, knowing that the
temperature is going to be fine. It always was.


Bricks, then an aluminum plate with big MIL resistors bolted to the
bottom. Gap-pad stuff stuck to the top, with the pot sitting on that.
Dunk a thermocouple into the brew. Design a controller or buy a cheap
Omega equivalent.


I assume with gap-pad you mean the stuff used to heatsink SMT
transistors et cetera to a nearby chassis panel. I wonder if that could
take the heat of a red-glowing spiral burner section. Then I could just
use my cooktops but have better heat coupling.

Lasse's idea of a heat jacket is a good one. I'd have to find a 3rd 120V
circuit nearby though.

I use a soft, gummy silicone stuff from 3G Shielding, about 6 w/mK,
pretty good heat conductor. The data sheet says 160C max.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Tom Gardner]

On 24/05/19 22:42, Joerg wrote:

There are two things that manufacturers generally do wrong. They do not provide
power levels in the 100W range so you can't easily use the cooktops for
slow-cooking. Then the temperature control granularity is way too coarse which
makes them less useful for brewing, pasteurization and many industrial processes.

Yes; that gobsmacked me.

The first single "ring" portable induction hob I bought my mother
(at 95 she was worried about a gar ring setting her sleeve on fire)
had exactly that problem. IIRC it was ~400W minimum, so it couldn't
even simmer a sauce!

It went straight back for a refund.

After some homework, the next one is just fine in that respect,
although it has more controls/options than desirable for a 97yo.
Example: the manual states that on the "boil" setting, it will
boil for "a while", grrr.

 

[whit3rd]

On Thursday, May 23, 2019 at 2:27:27 PM UTC-7, John Larkin wrote:

Grolsch has a nice bottle but it's otherwise bland. Lately we like
Guinness Blonde, Purple Haze, Widmer, and Harp. Mo likes Fat Tire but
I think it tastes funny.

If Widmer Hefeweizen is on tap, that's my favorite. For bottles, though,
fresh matters more than other qualities; in SF, I go with Anchor Steam.

In taste-testing while in college, the least expensive local brew was
preferable (because in the vicinity of campus, it was always moving
off the store shelf, so was always fresh).

 

[Joseph Gwinn]

On May 24, 2019, Joerg wrote
(in article <gkr6qbFc1oaU1@mid.individual.net&gt:

On 2019-05-24 14:12, Joseph Gwinn wrote:
On May 24, 2019, Joerg wrote
(in article <gkqf5pF72a9U1@mid.individual.net&gt:

On 2019-05-23 22:24, Mikko OH2HVJ wrote:
Joerg <news@analogconsultants.com> writes:

Thinking about induction cooktops for beer brewing because the two 1kW
..
However ... for reasons that I'll never understand the temperature can
only be set in 40F increments and very occasionally there are units
with 10F steps. Way too coarse for brewing. Even for sous-vide chefs
that isn't good enough. I am talking about the usual $50 price range,
not $1k restaurant grade. The thermostats on my $12 Walmart cooktops
are nicely analog-controlled so I can set them exactly where needed.

How is the temperature measured on those ? It might be the difficulty of
doing accurate temperature sensing with the ceramic plate in
between. IIRC some InGaAs photodiodes list this as one application in
their datasheets, but I would not expect to see those in cheaper units!

From what I saw so far in tear-downs there is a thermistor wadded into
something, right under the ceramic plate in the middle of the coil.
Probably a PTC or NTC resistor.

I´ve read some patents. That is exactly how it works. The heat is provided
in a ring, and measured in the center, well away from the heat path. Sort of
like a 4-wire resistance measurement.

I did come across one reasonably priced induction hob that claims to have
100-step power control. I bought and tested one of their models (PIC Gold),
and the 100-step claim is plausible. It is certainly far more than ten
levels, which is maddeningly coarse even for ordinary cooking.

Confusingly, they talk of four power levels: these are selectable maximum
power draw levels, so one can use the same hob in a house (full 1800 watts),
or on a RV or a boat (far less is available), without blowing breakers.

The power levels are nice, many have six or more. This one has 10 settings:

https://www.walmart.com/ip/Midea-1500W-Induction-Cooktop-Cooker-With-Stainless
-Steel-Pot-Table-Hotpot/405872121

There are two things that manufacturers generally do wrong. They do not
provide power levels in the 100W range so you can't easily use the
cooktops for slow-cooking. Then the temperature control granularity is
way too coarse which makes them less useful for brewing, pasteurization
and many industrial processes. Both could easily be provided at zero
extra cost.

The Walmart unit has only ten distinct power levels, far too coarse for even
ordinary cooking.

..

The induction hob in question is called NuWave and is made by Hearthwave, In

in Libertyville, IL 60048. NuWave LLC seems to have been stood up for this
business area.

PIC Pro ($180) is 1800 watts max:
.<https://nuwavenow.com/NuWavePIC?ref_version=DIRECT7&TM=1558731410289

.<https://nuwavenow.com/Patent

Their patents are useful for somewhat more technical detail than user-manual
level, but are also a bit confusing.

Their temp control happens at 10F granularity which unfortunately is too
coarse for brewing.

Derek Decker in a brewing NG suggested an interesting cooktop:

https://www.tastyonetop.com/

I'd have to inquire but it seems this might be controllable in 1F
increments and even has an external sensor. The alternative would be to
hack a regular induction top and have an external loop. With some
hysteresis I could hang a FET opto-coupler across the built-in center
thermistor and fool it into believing the temerature has been exceeded,
which woud turn it off until I let go.

This is a kind of Sous Vide unit. I do have an older Anova unit with 1F
granularity that falls between the $50 junk and the $1000 restaurant
equipment. Here is a current offering I received in February (but the link
still works):

..<https://anovaculinary.com/anova-precision-
cooker/?utm_source=01.+Primary+Marketing+List&utm_campaign=377be49a07-
acquisition_email&utm_medium=email&utm_term=0_f33347b916-377be49a07-
99967053&goal=0_f33347b916-377be49a07-
99967053&mc_cid=377be49a07&mc_eid=682d82d06a>

The occasion was to announce that Anova is being acquired by Electrolux.

Anova´s top-of-line "Pro" version is $400, and seems more suited to a
restaurant.

I´d bet that one would not immerse the immersion heater directly in the
beer mash, instead using the heater to keep a water bath at temperature, with
the beer in a pot sitting in the bath.

..

That still leaves the question how far the steel plate could be from the
cooktop. Jan's experiment was encouraging, he held the pan about half an
inch away in the air and it still cooked an egg. He forgot the bacon
though ...

NuWave induction cookware gets very bad reviews. ...

We've had a sort of radiant heat cooker here from a friend. It had a big
pot and the heater unit was in a thick lid. Wasn't impressed. The
quality was ok, just the general idea of cooking that way wasn't, IMHO.

... European cookware rated for induction works well.

I have relatives there so someone could bring it when visiting. It's not
a slam dunk though because most are rated 230V and our two-phase easily
goes to 255V for hours. I could use a 24V step-down but that starts to
get old.

I never knew that pots and pans also were rated for mains voltage ranges in
Europe.

Joe Gwinn

 

[Joerg]

On 2019-05-25 07:07, Joseph Gwinn wrote:

On May 24, 2019, Joerg wrote
(in article <gkr6qbFc1oaU1@mid.individual.net&gt:

On 2019-05-24 14:12, Joseph Gwinn wrote:
On May 24, 2019, Joerg wrote
(in article <gkqf5pF72a9U1@mid.individual.net&gt:

On 2019-05-23 22:24, Mikko OH2HVJ wrote:
Joerg <news@analogconsultants.com> writes:

Thinking about induction cooktops for beer brewing because the two 1kW
..
However ... for reasons that I'll never understand the temperature can
only be set in 40F increments and very occasionally there are units
with 10F steps. Way too coarse for brewing. Even for sous-vide chefs
that isn't good enough. I am talking about the usual $50 price range,
not $1k restaurant grade. The thermostats on my $12 Walmart cooktops
are nicely analog-controlled so I can set them exactly where needed.

How is the temperature measured on those ? It might be the difficulty of
doing accurate temperature sensing with the ceramic plate in
between. IIRC some InGaAs photodiodes list this as one application in
their datasheets, but I would not expect to see those in cheaper units!

From what I saw so far in tear-downs there is a thermistor wadded into
something, right under the ceramic plate in the middle of the coil.
Probably a PTC or NTC resistor.

I´ve read some patents. That is exactly how it works. The heat is provided
in a ring, and measured in the center, well away from the heat path. Sort of
like a 4-wire resistance measurement.

I did come across one reasonably priced induction hob that claims to have
100-step power control. I bought and tested one of their models (PIC Gold),
and the 100-step claim is plausible. It is certainly far more than ten
levels, which is maddeningly coarse even for ordinary cooking.

Confusingly, they talk of four power levels: these are selectable maximum
power draw levels, so one can use the same hob in a house (full 1800 watts),
or on a RV or a boat (far less is available), without blowing breakers.

The power levels are nice, many have six or more. This one has 10 settings:

https://www.walmart.com/ip/Midea-1500W-Induction-Cooktop-Cooker-With-Stainless
-Steel-Pot-Table-Hotpot/405872121

There are two things that manufacturers generally do wrong. They do not
provide power levels in the 100W range so you can't easily use the
cooktops for slow-cooking. Then the temperature control granularity is
way too coarse which makes them less useful for brewing, pasteurization
and many industrial processes. Both could easily be provided at zero
extra cost.

The Walmart unit has only ten distinct power levels, far too coarse for even
ordinary cooking.

The power levels would be ok if they offer some below 200W for
slow-cooking. The temperature is the problems. Standard is 40F
increments (useless) and occasionally 10F increments which is still not
ok for some jobs.

.
The induction hob in question is called NuWave and is made by Hearthwave, In

in Libertyville, IL 60048. NuWave LLC seems to have been stood up for this
business area.

PIC Pro ($180) is 1800 watts max:
.<https://nuwavenow.com/NuWavePIC?ref_version=DIRECT7&TM=1558731410289

.<https://nuwavenow.com/Patent

Their patents are useful for somewhat more technical detail than user-manual
level, but are also a bit confusing.

Their temp control happens at 10F granularity which unfortunately is too
coarse for brewing.

Derek Decker in a brewing NG suggested an interesting cooktop:

https://www.tastyonetop.com/

I'd have to inquire but it seems this might be controllable in 1F
increments and even has an external sensor. The alternative would be to
hack a regular induction top and have an external loop. With some
hysteresis I could hang a FET opto-coupler across the built-in center
thermistor and fool it into believing the temerature has been exceeded,
which woud turn it off until I let go.

This is a kind of Sous Vide unit. I do have an older Anova unit with 1F
granularity that falls between the $50 junk and the $1000 restaurant
equipment. Here is a current offering I received in February (but the link
still works):

.<https://anovaculinary.com/anova-precision-
cooker/?utm_source=01.+Primary+Marketing+List&utm_campaign=377be49a07-
acquisition_email&utm_medium=email&utm_term=0_f33347b916-377be49a07-
99967053&goal=0_f33347b916-377be49a07-
99967053&mc_cid=377be49a07&mc_eid=682d82d06a

The occasion was to announce that Anova is being acquired by Electrolux.

Anova´s top-of-line "Pro" version is $400, and seems more suited to a
restaurant.

I´d bet that one would not immerse the immersion heater directly in the
beer mash, ...

Can't because the lid must be mostly closed or you can't keep a boil at
the available power level. Also, the innards would crud up unbelievably.

... instead using the heater to keep a water bath at temperature, with
the beer in a pot sitting in the bath.

The I'd need an even bigger pot to hold my monster pot. That's not going
to work. Immersion can work and some brewers do it but the stick has do
be completely without cavities, must have easily cleanable surfaces
everywhere and unfortunately it really gets in the way when stirring.

They look like this:

https://www.amazon.com/Home-Heater-Bucket-immersion-heater/dp/B07GNTBSHQ

https://1lw1tk46gr9aum2ilzzghvk5-wpengine.netdna-ssl.com/wp-content/uploads/2016/11/Screen-Shot-2016-11-14-at-3.54.09-PM.png

Most are 240V, are in the 4000-5500W class and you have to use an
external temperature control loop:

https://www.amazon.com/Dernord-Immersion-Foldback-Brewing-Tubular/dp/B06XR8NGLP

Key is to have a good old analog thermostat or, if it must be digital,
have 1F granularity.

.
That still leaves the question how far the steel plate could be from the
cooktop. Jan's experiment was encouraging, he held the pan about half an
inch away in the air and it still cooked an egg. He forgot the bacon
though ...

NuWave induction cookware gets very bad reviews. ...

We've had a sort of radiant heat cooker here from a friend. It had a big
pot and the heater unit was in a thick lid. Wasn't impressed. The
quality was ok, just the general idea of cooking that way wasn't, IMHO.

... European cookware rated for induction works well.

I have relatives there so someone could bring it when visiting. It's not
a slam dunk though because most are rated 230V and our two-phase easily
goes to 255V for hours. I could use a 24V step-down but that starts to
get old.

I never knew that pots and pans also were rated for mains voltage ranges in
Europe.

Sometimes they have that built in. We've got wome but now all American,
after moving here from Europe.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joseph Gwinn]

On May 25, 2019, Joerg wrote
(in article <gkt2fqFo5k5U1@mid.individual.net&gt:

On 2019-05-25 07:07, Joseph Gwinn wrote:
On May 24, 2019, Joerg wrote
(in article <gkr6qbFc1oaU1@mid.individual.net&gt:

On 2019-05-24 14:12, Joseph Gwinn wrote:
On May 24, 2019, Joerg wrote
(in article <gkqf5pF72a9U1@mid.individual.net&gt:

On 2019-05-23 22:24, Mikko OH2HVJ wrote:
Joerg <news@analogconsultants.com> writes:

Thinking about induction cooktops for beer brewing because the two
1kW
..
However ... for reasons that I'll never understand the temperature
can
only be set in 40F increments and very occasionally there are unit

with 10F steps. Way too coarse for brewing. Even for sous-vide che
s
that isn't good enough. I am talking about the usual $50 price ran
e,
not $1k restaurant grade. The thermostats on my $12 Walmart cookto
s
are nicely analog-controlled so I can set them exactly where neede
..

How is the temperature measured on those ? It might be the difficult
of
doing accurate temperature sensing with the ceramic plate in
between. IIRC some InGaAs photodiodes list this as one application i

their datasheets, but I would not expect to see those in cheaper uni
s!

From what I saw so far in tear-downs there is a thermistor wadded into
something, right under the ceramic plate in the middle of the coil.
Probably a PTC or NTC resistor.

I´ve read some patents. That is exactly how it works. The heat is
provided
in a ring, and measured in the center, well away from the heat path. Sor

of
like a 4-wire resistance measurement.

I did come across one reasonably priced induction hob that claims to hav

100-step power control. I bought and tested one of their models (PIC
Gold),
and the 100-step claim is plausible. It is certainly far more than ten
levels, which is maddeningly coarse even for ordinary cooking.

Confusingly, they talk of four power levels: these are selectable maximu

power draw levels, so one can use the same hob in a house (full 1800
watts),
or on a RV or a boat (far less is available), without blowing breakers.

The power levels are nice, many have six or more. This one has 10 settings


https://www.walmart.com/ip/Midea-1500W-Induction-Cooktop-Cooker-With-Stain

ess
-Steel-Pot-Table-Hotpot/405872121

There are two things that manufacturers generally do wrong. They do not
provide power levels in the 100W range so you can't easily use the
cooktops for slow-cooking. Then the temperature control granularity is
way too coarse which makes them less useful for brewing, pasteurization
and many industrial processes. Both could easily be provided at zero
extra cost.

The Walmart unit has only ten distinct power levels, far too coarse for even
ordinary cooking.

The power levels would be ok if they offer some below 200W for
slow-cooking. The temperature is the problems. Standard is 40F
increments (useless) and occasionally 10F increments which is still not
ok for some jobs.

Even with ordinary gas or thermal electric (non induction) hobs, this is a
problem. Sellers talk only about max power out, and less about
controllability, and almost not at all about being able to simmer with any
control. It takes an expensive unit to do all these well. I recently replaced
a gas stove, and simmer was a big need. The solution was an electronic module
that turns the flame on and off periodically. This gets around the limited
dynamic range of a burner, maybe 9:1 for a very good unit.

.
The induction hob in question is called NuWave and is made by Hearthwave

In
in Libertyville, IL 60048. NuWave LLC seems to have been stood up for th
s
business area.

PIC Pro ($180) is 1800 watts max:
.<https://nuwavenow.com/NuWavePIC?ref_version=DIRECT7&TM=15587314102
9

.<https://nuwavenow.com/Patent

Their patents are useful for somewhat more technical detail than
user-manual
level, but are also a bit confusing.

Their temp control happens at 10F granularity which unfortunately is too
coarse for brewing.

Derek Decker in a brewing NG suggested an interesting cooktop:

https://www.tastyonetop.com/

I'd have to inquire but it seems this might be controllable in 1F
increments and even has an external sensor. The alternative would be to
hack a regular induction top and have an external loop. With some
hysteresis I could hang a FET opto-coupler across the built-in center
thermistor and fool it into believing the temerature has been exceeded,
which woud turn it off until I let go.

This is a kind of Sous Vide unit. I do have an older Anova unit with 1F
granularity that falls between the $50 junk and the $1000 restaurant
equipment. Here is a current offering I received in February (but the link
still works):

.<https://anovaculinary.com/anova-precision-
cooker/?utm_source=01.+Primary+Marketing+List&utm_campaign=377be49a07-
acquisition_email&utm_medium=email&utm_term=0_f33347b916-377be49a07-
99967053&goal=0_f33347b916-377be49a07-
99967053&mc_cid=377be49a07&mc_eid=682d82d06a

The occasion was to announce that Anova is being acquired by Electrolux.

Anova´s top-of-line "Pro" version is $400, and seems more suited to a
restaurant.

I´d bet that one would not immerse the immersion heater directly in the
beer mash, ...

Can't because the lid must be mostly closed or you can't keep a boil at
the available power level. Also, the innards would crud up unbelievably.

... instead using the heater to keep a water bath at temperature, with
the beer in a pot sitting in the bath.

The I'd need an even bigger pot to hold my monster pot. That's not going
to work. Immersion can work and some brewers do it but the stick has do
be completely without cavities, must have easily cleanable surfaces
everywhere and unfortunately it really gets in the way when stirring.

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

.
They look like this:

https://www.amazon.com/Home-Heater-Bucket-immersion-heater/dp/B07GNTBSHQ

https://1lw1tk46gr9aum2ilzzghvk5-wpengine.netdna-ssl.com/wp-content/uploads/20
16/11/Screen-Shot-2016-11-14-at-3.54.09-PM.png

Most are 240V, are in the 4000-5500W class and you have to use an
external temperature control loop:

https://www.amazon.com/Dernord-Immersion-Foldback-Brewing-Tubular/dp/B06XR8NG

P

Key is to have a good old analog thermostat or, if it must be digital,
have 1F granularity.

.
That still leaves the question how far the steel plate could be from the
cooktop. Jan's experiment was encouraging, he held the pan about half an
inch away in the air and it still cooked an egg. He forgot the bacon
though ...

NuWave induction cookware gets very bad reviews. ...

We've had a sort of radiant heat cooker here from a friend. It had a big
pot and the heater unit was in a thick lid. Wasn't impressed. The
quality was ok, just the general idea of cooking that way wasn't, IMHO.

... European cookware rated for induction works well.

I have relatives there so someone could bring it when visiting. It's not
a slam dunk though because most are rated 230V and our two-phase easily
goes to 255V for hours. I could use a 24V step-down but that starts to
get old.

I never knew that pots and pans also were rated for mains voltage ranges in
Europe.

Sometimes they have that built in. We've got some but now all American,
after moving here from Europe.

The difference is between cooktops (with hobs) and cookware (pots and pans,
only some of which can be heated by an induction hob).

 

[Joerg]

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

On May 25, 2019, Joerg wrote
(in article <gkt2fqFo5k5U1@mid.individual.net&gt:

On 2019-05-25 07:07, Joseph Gwinn wrote:
On May 24, 2019, Joerg wrote
(in article <gkr6qbFc1oaU1@mid.individual.net&gt:

On 2019-05-24 14:12, Joseph Gwinn wrote:
On May 24, 2019, Joerg wrote
(in article <gkqf5pF72a9U1@mid.individual.net&gt:

On 2019-05-23 22:24, Mikko OH2HVJ wrote:
Joerg <news@analogconsultants.com> writes:

Thinking about induction cooktops for beer brewing because the two
1kW
..
However ... for reasons that I'll never understand the temperature
can
only be set in 40F increments and very occasionally there are unit

with 10F steps. Way too coarse for brewing. Even for sous-vide che
s
that isn't good enough. I am talking about the usual $50 price ran
e,
not $1k restaurant grade. The thermostats on my $12 Walmart cookto
s
are nicely analog-controlled so I can set them exactly where neede
.

How is the temperature measured on those ? It might be the difficult
of
doing accurate temperature sensing with the ceramic plate in
between. IIRC some InGaAs photodiodes list this as one application i

their datasheets, but I would not expect to see those in cheaper uni
s!

From what I saw so far in tear-downs there is a thermistor wadded into
something, right under the ceramic plate in the middle of the coil.
Probably a PTC or NTC resistor.

I´ve read some patents. That is exactly how it works. The heat is
provided
in a ring, and measured in the center, well away from the heat path. Sor

of
like a 4-wire resistance measurement.

I did come across one reasonably priced induction hob that claims to hav

100-step power control. I bought and tested one of their models (PIC
Gold),
and the 100-step claim is plausible. It is certainly far more than ten
levels, which is maddeningly coarse even for ordinary cooking.

Confusingly, they talk of four power levels: these are selectable maximu

power draw levels, so one can use the same hob in a house (full 1800
watts),
or on a RV or a boat (far less is available), without blowing breakers.

The power levels are nice, many have six or more. This one has 10 settings


https://www.walmart.com/ip/Midea-1500W-Induction-Cooktop-Cooker-With-Stain

ess
-Steel-Pot-Table-Hotpot/405872121

There are two things that manufacturers generally do wrong. They do not
provide power levels in the 100W range so you can't easily use the
cooktops for slow-cooking. Then the temperature control granularity is
way too coarse which makes them less useful for brewing, pasteurization
and many industrial processes. Both could easily be provided at zero
extra cost.

The Walmart unit has only ten distinct power levels, far too coarse for even
ordinary cooking.

The power levels would be ok if they offer some below 200W for
slow-cooking. The temperature is the problems. Standard is 40F
increments (useless) and occasionally 10F increments which is still not
ok for some jobs.

Even with ordinary gas or thermal electric (non induction) hobs, this is a
problem. Sellers talk only about max power out, and less about
controllability, and almost not at all about being able to simmer with any
control. It takes an expensive unit to do all these well. I recently replaced
a gas stove, and simmer was a big need. The solution was an electronic module
that turns the flame on and off periodically. This gets around the limited
dynamic range of a burner, maybe 9:1 for a very good unit.

To my surprise this works very well on the $10-12 Walmart electric coil
cooktops. I can set one to slightly above "1" and it'll hold 156F to
within +/-2F, good enough.

.
The induction hob in question is called NuWave and is made by Hearthwave

In
in Libertyville, IL 60048. NuWave LLC seems to have been stood up for th
s
business area.

PIC Pro ($180) is 1800 watts max:
.<https://nuwavenow.com/NuWavePIC?ref_version=DIRECT7&TM=15587314102
9

.<https://nuwavenow.com/Patent

Their patents are useful for somewhat more technical detail than
user-manual
level, but are also a bit confusing.

Their temp control happens at 10F granularity which unfortunately is too
coarse for brewing.

Derek Decker in a brewing NG suggested an interesting cooktop:

https://www.tastyonetop.com/

I'd have to inquire but it seems this might be controllable in 1F
increments and even has an external sensor. The alternative would be to
hack a regular induction top and have an external loop. With some
hysteresis I could hang a FET opto-coupler across the built-in center
thermistor and fool it into believing the temerature has been exceeded,
which woud turn it off until I let go.

This is a kind of Sous Vide unit. I do have an older Anova unit with 1F
granularity that falls between the $50 junk and the $1000 restaurant
equipment. Here is a current offering I received in February (but the link
still works):

.<https://anovaculinary.com/anova-precision-
cooker/?utm_source=01.+Primary+Marketing+List&utm_campaign=377be49a07-
acquisition_email&utm_medium=email&utm_term=0_f33347b916-377be49a07-
99967053&goal=0_f33347b916-377be49a07-
99967053&mc_cid=377be49a07&mc_eid=682d82d06a

The occasion was to announce that Anova is being acquired by Electrolux.

Anova´s top-of-line "Pro" version is $400, and seems more suited to a
restaurant.

I´d bet that one would not immerse the immersion heater directly in the
beer mash, ...

Can't because the lid must be mostly closed or you can't keep a boil at
the available power level. Also, the innards would crud up unbelievably.

... instead using the heater to keep a water bath at temperature, with
the beer in a pot sitting in the bath.

The I'd need an even bigger pot to hold my monster pot. That's not going
to work. Immersion can work and some brewers do it but the stick has do
be completely without cavities, must have easily cleanable surfaces
everywhere and unfortunately it really gets in the way when stirring.

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 shorter
or it woudn't straddle my two cooktops.

.
They look like this:

https://www.amazon.com/Home-Heater-Bucket-immersion-heater/dp/B07GNTBSHQ

https://1lw1tk46gr9aum2ilzzghvk5-wpengine.netdna-ssl.com/wp-content/uploads/20
16/11/Screen-Shot-2016-11-14-at-3.54.09-PM.png

Most are 240V, are in the 4000-5500W class and you have to use an
external temperature control loop:

https://www.amazon.com/Dernord-Immersion-Foldback-Brewing-Tubular/dp/B06XR8NG

P

Key is to have a good old analog thermostat or, if it must be digital,
have 1F granularity.

.
That still leaves the question how far the steel plate could be from the
cooktop. Jan's experiment was encouraging, he held the pan about half an
inch away in the air and it still cooked an egg. He forgot the bacon
though ...

NuWave induction cookware gets very bad reviews. ...

We've had a sort of radiant heat cooker here from a friend. It had a big
pot and the heater unit was in a thick lid. Wasn't impressed. The
quality was ok, just the general idea of cooking that way wasn't, IMHO.

... European cookware rated for induction works well.

I have relatives there so someone could bring it when visiting. It's not
a slam dunk though because most are rated 230V and our two-phase easily
goes to 255V for hours. I could use a 24V step-down but that starts to
get old.

I never knew that pots and pans also were rated for mains voltage ranges in
Europe.

Sometimes they have that built in. We've got some but now all American,
after moving here from Europe.

The difference is between cooktops (with hobs) and cookware (pots and pans,
only some of which can be heated by an induction hob).

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

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joseph Gwinn]

On May 26, 2019, Joerg wrote
(in article <gl06onFeclbU1@mid.individual.net&gt:

On 2019-05-26 09:14, Joseph Gwinn wrote:
On May 25, 2019, Joerg wrote
(in article <gkt2fqFo5k5U1@mid.individual.net&gt:

[snip]
The power levels would be ok if they offer some below 200W for
slow-cooking. The temperature is the problems. Standard is 40F
increments (useless) and occasionally 10F increments which is still not
ok for some jobs.

Even with ordinary gas or thermal electric (non induction) hobs, this is a
problem. Sellers talk only about max power out, and less about
controllability, and almost not at all about being able to simmer with any
control. It takes an expensive unit to do all these well. I recently
replaced
a gas stove, and simmer was a big need. The solution was an electronic
module
that turns the flame on and off periodically. This gets around the limited
dynamic range of a burner, maybe 9:1 for a very good unit.

To my surprise this works very well on the $10-12 Walmart electric coil
cooktops. I can set one to slightly above "1" and it'll hold 156F to
within +/-2F, good enough.

KISS wins. That electric-coil unit must have a control with more than ten
steps, but with only ten levels marked.

What I did in the old days, when electric-coil hobs had four settings
(including off), was to use such a hob set to full power, but driven from a
variac. Now days, one would use a solid-state variable power control intended
for a hot tub.

..

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 shorter
or it woudn't straddle my two cooktops.

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

..

I never knew that pots and pans also were rated for mains voltage ranges
in Europe.

Sometimes they have that built in. We've got some but now all American,
after moving here from Europe.

The difference is between cooktops (with hobs) and cookware (pots and pans,
only some of which can be heated by an induction hob).

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.

Joe Gwinn

 

[Joerg]

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:
On May 25, 2019, Joerg wrote
(in article <gkt2fqFo5k5U1@mid.individual.net&gt:

[snip]
The power levels would be ok if they offer some below 200W for
slow-cooking. The temperature is the problems. Standard is 40F
increments (useless) and occasionally 10F increments which is still not
ok for some jobs.

Even with ordinary gas or thermal electric (non induction) hobs, this is a
problem. Sellers talk only about max power out, and less about
controllability, and almost not at all about being able to simmer with any
control. It takes an expensive unit to do all these well. I recently
replaced
a gas stove, and simmer was a big need. The solution was an electronic
module
that turns the flame on and off periodically. This gets around the limited
dynamic range of a burner, maybe 9:1 for a very good unit.

To my surprise this works very well on the $10-12 Walmart electric coil
cooktops. I can set one to slightly above "1" and it'll hold 156F to
within +/-2F, good enough.

KISS wins. That electric-coil unit must have a control with more than ten
steps, but with only ten levels marked.

No steps and that's just the trick. It's totally analog, a bi-metal
thermostat with a worm gear and a knob. In digital that could easily be
emulated at zero cost but they don't do it.

What I did in the old days, when electric-coil hobs had four settings
(including off), was to use such a hob set to full power, but driven from 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 not
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.

.
[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 shorter
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.

.
[snip]
I never knew that pots and pans also were rated for mains voltage ranges
in Europe.

Sometimes they have that built in. We've got some but now all American,
after moving here from Europe.

The difference is between cooktops (with hobs) and cookware (pots and pans,
only some of which can be heated by an induction hob).

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

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 2019-05-27 07:28, Joerg wrote:

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:
On May 25, 2019, Joerg wrote
(in article <gkt2fqFo5k5U1@mid.individual.net&gt:

[snip]
The power levels would be ok if they offer some below 200W for
slow-cooking. The temperature is the problems. Standard is 40F
increments (useless) and occasionally 10F increments which is still
not
ok for some jobs.

Even with ordinary gas or thermal electric (non induction) hobs,
this is a
problem. Sellers talk only about max power out, and less about
controllability, and almost not at all about being able to simmer
with any
control. It takes an expensive unit to do all these well. I recently
replaced
a gas stove, and simmer was a big need. The solution was an electronic
module
that turns the flame on and off periodically. This gets around the
limited
dynamic range of a burner, maybe 9:1 for a very good unit.

To my surprise this works very well on the $10-12 Walmart electric coil
cooktops. I can set one to slightly above "1" and it'll hold 156F to
within +/-2F, good enough.

KISS wins. That electric-coil unit must have a control with more than ten
steps, but with only ten levels marked.


No steps and that's just the trick. It's totally analog, a bi-metal
thermostat with a worm gear and a knob. In digital that could easily be
emulated at zero cost but they don't do it.


What I did in the old days, when electric-coil hobs had four settings
(including off), was to use such a hob set to full power, but driven
from 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 not
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.

.
[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 shorter
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.

Just measured it, it is 15-3/8" or 39cm deep. I am brewing an Irish Red
Ale right now and currently the steeping grains are in. As usual, one of
the cheap Walmart burners is holding it at exactly 156F. It just took 1h
10mins to get there. Since it's cold right now it'll be well over
another hour to get from there to a rolling boil. Meaning I can't brew
the 2nd beer today because I am also Mr.Barbecue later and it's a more
time consuming meal.

.
[snip]
I never knew that pots and pans also were rated for mains voltage
ranges
in Europe.

Sometimes they have that built in. We've got some but now all
American,
after moving here from Europe.

The difference is between cooktops (with hobs) and cookware (pots
and pans,
only some of which can be heated by an induction hob).

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

--
Regards, Joerg

http://www.analogconsultants.com/

 

[John Larkin]

On Mon, 27 May 2019 08:19:51 -0700, Joerg <news@analogconsultants.com>
wrote:

On 2019-05-27 07:28, Joerg wrote:
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:
On May 25, 2019, Joerg wrote
(in article <gkt2fqFo5k5U1@mid.individual.net&gt:

[snip]
The power levels would be ok if they offer some below 200W for
slow-cooking. The temperature is the problems. Standard is 40F
increments (useless) and occasionally 10F increments which is still
not
ok for some jobs.

Even with ordinary gas or thermal electric (non induction) hobs,
this is a
problem. Sellers talk only about max power out, and less about
controllability, and almost not at all about being able to simmer
with any
control. It takes an expensive unit to do all these well. I recently
replaced
a gas stove, and simmer was a big need. The solution was an electronic
module
that turns the flame on and off periodically. This gets around the
limited
dynamic range of a burner, maybe 9:1 for a very good unit.

To my surprise this works very well on the $10-12 Walmart electric coil
cooktops. I can set one to slightly above "1" and it'll hold 156F to
within +/-2F, good enough.

KISS wins. That electric-coil unit must have a control with more than ten
steps, but with only ten levels marked.


No steps and that's just the trick. It's totally analog, a bi-metal
thermostat with a worm gear and a knob. In digital that could easily be
emulated at zero cost but they don't do it.


What I did in the old days, when electric-coil hobs had four settings
(including off), was to use such a hob set to full power, but driven
from 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 not
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.

.
[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 shorter
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.


Just measured it, it is 15-3/8" or 39cm deep. I am brewing an Irish Red
Ale right now and currently the steeping grains are in. As usual, one of
the cheap Walmart burners is holding it at exactly 156F. It just took 1h
10mins to get there. Since it's cold right now it'll be well over
another hour to get from there to a rolling boil.

It's snowing now a bit uphill from you.


--

John Larkin Highland Technology, Inc trk

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Joseph Gwinn]

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:
On May 25, 2019, Joerg wrote
(in article <gkt2fqFo5k5U1@mid.individual.net&gt:

[snip]
The power levels would be ok if they offer some below 200W for
slow-cooking. The temperature is the problems. Standard is 40F
increments (useless) and occasionally 10F increments which is still no

ok for some jobs.

Even with ordinary gas or thermal electric (non induction) hobs, this is
a
problem. Sellers talk only about max power out, and less about
controllability, and almost not at all about being able to simmer with a
y
control. It takes an expensive unit to do all these well. I recently
replaced
a gas stove, and simmer was a big need. The solution was an electronic
module
that turns the flame on and off periodically. This gets around the limit
d
dynamic range of a burner, maybe 9:1 for a very good unit.

To my surprise this works very well on the $10-12 Walmart electric coil
cooktops. I can set one to slightly above "1" and it'll hold 156F to
within +/-2F, good enough.

KISS wins. That electric-coil unit must have a control with more than ten
steps, but with only ten levels marked.

No steps and that's just the trick. It's totally analog, a bi-metal
thermostat with a worm gear and a knob. In digital that could easily be
emulated at zero cost but they don't do it.

What I did in the old days, when electric-coil hobs had four settings
(including off), was to use such a hob set to full power, but driven from 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 not
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 controller
plus a 12-volt DC relay to turn the hob AC power on and off, replacing the
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).

.
[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 shorter
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.

.
[snip]
I never knew that pots and pans also were rated for mains voltage ra
ges
in Europe.

Sometimes they have that built in. We've got some but now all American

after moving here from Europe.

The difference is between cooktops (with hobs) and cookware (pots and
pans,
only some of which can be heated by an induction hob).

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 find
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 that is
heated by the induction heater. But that´s way more complex than an
electric coil, a thermocouple, and an industrial temperature controller.

Joe Gwinn

 

Ebay/ Amazon is your friend on this one. Large amounts of OEM Induction Cooker driver modules for sale. Some have already been hacked, except the hacking is documented in blog posts, not wen sites, so a little difficult to find.


If you want to make your heated region an extension pipe off the main tank, we've had really good luck at the university playing with the 48V 1 KW Royer Oscillator modules from Ebay. You cant tune them much, so you have to tune the load design. Easily heats the right diameter pipe, silicon nitride tube, or screwdriver to glowing red. They are cheap enough to be throwaways in the lab.


If you are really cleaver, you can design the induction heater as an inverted / reentrant finger "Into" the tank. Some form of forced circulation would be a must.

I've had a 1KW induction hob for 4 years ago, paid 75$ for it, and love it for heating dishes at parties/meetings at work, and in the local park, where they provide 110VAC. Not allowed to have propane stoves / charcoal grilles on the quad at the university unless you are Department Chair or above.... Induction and an extension cord got me a wink from Health and Safety.

Steve

 

[Jan Panteltje]

On a sunny day (Mon, 27 May 2019 11:05:13 -0700 (PDT)) it happened
sroberts6328@gmail.com wrote in
<55e4bca7-e269-4ba4-8f70-2e1157dd9968@googlegroups.com>:

Ebay/ Amazon is your friend on this one. Large amounts of OEM Induction Cooker
driver modules for sale. Some have already been hacked, except the hacking
is documented in blog posts, not wen sites, so a little difficult to find.


If
you want to make your heated region an extension pipe off the main tank,
we've had really good luck at the university playing with the 48V 1 KW Royer
Oscillator modules from Ebay. You cant tune them much, so you have to tune
the load design. Easily heats the right diameter pipe, silicon nitride
tube, or screwdriver to glowing red. They are cheap enough to be throwaways
in the lab.


If you are really cleaver, you can design the induction heater as an inverted
/ reentrant finger "Into" the tank. Some form of forced circulation would
be a must.

I've had a 1KW induction hob for 4 years ago, paid 75$ for it, and love it for
heating dishes at parties/meetings at work, and in the local park, where
they provide 110VAC. Not allowed to have propane stoves / charcoal grilles
on the quad at the university unless you are Department Chair or above...
Induction and an extension cord got me a wink from Health and Safety.

Steve

If you ever need some voltage and have no transformer at hand,
then this works fine:
http://panteltje.com/pub/inductive_coupling_real_power_300Vpp_IMG_6092.JPG

Use your induction heater!

The normal kitchen ones need a piece of iron, have a micro switch with magnet
to detect if there is something on it I think.

 

[Joerg]

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 settings
(including off), was to use such a hob set to full power, but driven from 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 not
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 controller
plus a 12-volt DC relay to turn the hob AC power on and off, replacing the
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.

.
[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 shorter
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 change 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.

.
[snip]
I never knew that pots and pans also were rated for mains voltage ra
ges
in Europe.

Sometimes they have that built in. We've got some but now all American

after moving here from Europe.

The difference is between cooktops (with hobs) and cookware (pots and
pans,
only some of which can be heated by an induction hob).

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 find
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 that 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.

--
Regards, Joerg

http://www.analogconsultants.com/