Induction heating for brew kettle

[Joerg]

Currently I am using two 1000W electric burners that my very wide
13-gallon aluminum brew kettle straddles. They plug into two different
circuits. My batches are 5-gallon and to make up for boil-off I start
with slightly above 5-1/2 gallons. 70F to 155F takes a whole hour, 155F
to 207F boil takes more than another hour.

A few ideas a swirling around in my head on how to speed this up without
investing a ton of money. One of them is to buy two 120V induction
burners which come in 1800W, so more oomph. I'd probably set them to
1500W in order not to overtax a circuit. Cost is about $50 a piece. Of
course, the aluminum pot would not work by itself and here comes my
first question:

Does anyone know whether laying a big round steel disc inside the kettle
would make this work efficiently? Considering the thickness of the
aluminum bottom of the kettle the distance from the ceramic cooktop
surfaces to that plate could exceed 1/8".

Second question: If the power were the same how moch more efficient is
induction heating versus regular electric burners in your experience?

[Derek J Decker]

Post by Joerg
Currently I am using two 1000W electric burners that my very wide
13-gallon aluminum brew kettle straddles. They plug into two different
circuits. My batches are 5-gallon and to make up for boil-off I start
with slightly above 5-1/2 gallons. 70F to 155F takes a whole hour, 155F
to 207F boil takes more than another hour.
A few ideas a swirling around in my head on how to speed this up without
investing a ton of money. One of them is to buy two 120V induction
burners which come in 1800W, so more oomph. I'd probably set them to
1500W in order not to overtax a circuit. Cost is about $50 a piece. Of
course, the aluminum pot would not work by itself and here comes my
Does anyone know whether laying a big round steel disc inside the kettle
would make this work efficiently? Considering the thickness of the
aluminum bottom of the kettle the distance from the ceramic cooktop
surfaces to that plate could exceed 1/8".

I purchased an induction burner a few months ago because it was on sale
for $28 at Aldi - at that price, hey, new toy! And it works very well -
certainly boiled water faster than my electric coils.

But it didn't work with my copper-bottom Revereware pots, which limited
what I could do with it. So I bought this:

<https://www.amazon.com/gp/product/B07C2QTB3V/>

which is basically a stainless steel disk with a handle, and is built
precisely for this task. This goes under the pot you want to heat, and
not inside it - induction makes the disk hot, which makes your pot hot,
which boils the water. This is slightly less efficient than just
directly heating a compatible pot, but still works well.

My induction burner has two control methods - heat to a controlled temp,
or run at a particular power. I can run the burner at its highest power
with an induction-compatible pot of water on it.

If I use the disk with a non-compatible pot at full power, the disc will
overheat, and the burner will shut down till things cool off. The trick
when using the disk is to set the burner to maintain the highest possible
temperature (around 400°F is what I recall). This causes the burner to
modulate its power output and not overheat. 'Course, you're putting less
wattage into the pot than the burner could theoretically put out

Of course, if you're running two 1800 Watt devices at once, you'll want
them to be on separate circuits.

summary:

1) Steel disk works, is a standard product you can buy for this
application

2) Disk goes under the pot, not inside

3) Disk reduces efficiency some, overheating may result

Post by Joerg
Second question: If the power were the same how moch more efficient is
induction heating versus regular electric burners in your experience?

I could do controlled scientific experiments, but I haven't yet. I am of
the opinion that a higher percentage of the heat generated by induction
goes to the pot and not the surrounding air, etc

-Derek

[Joerg]

Post by Derek J Decker

Post by Joerg
Currently I am using two 1000W electric burners that my very wide
13-gallon aluminum brew kettle straddles. They plug into two different
circuits. My batches are 5-gallon and to make up for boil-off I start
with slightly above 5-1/2 gallons. 70F to 155F takes a whole hour, 155F
to 207F boil takes more than another hour.
A few ideas a swirling around in my head on how to speed this up without
investing a ton of money. One of them is to buy two 120V induction
burners which come in 1800W, so more oomph. I'd probably set them to
1500W in order not to overtax a circuit. Cost is about $50 a piece. Of
course, the aluminum pot would not work by itself and here comes my
Does anyone know whether laying a big round steel disc inside the kettle
would make this work efficiently? Considering the thickness of the
aluminum bottom of the kettle the distance from the ceramic cooktop
surfaces to that plate could exceed 1/8".

I purchased an induction burner a few months ago because it was on sale
for $28 at Aldi - at that price, hey, new toy! And it works very well -
certainly boiled water faster than my electric coils.

$28, wow! Unfortunately we don't have Aldi in Northern California.

Post by Derek J Decker
But it didn't work with my copper-bottom Revereware pots, which limited
<https://www.amazon.com/gp/product/B07C2QTB3V/>
which is basically a stainless steel disk with a handle, and is built
precisely for this task. This goes under the pot you want to heat, and
not inside it - induction makes the disk hot, which makes your pot hot,
which boils the water. This is slightly less efficient than just
directly heating a compatible pot, but still works well.

From what I've read on the Internet the "under the pot" transfer plates
make things less efficient than the old electric coil cooktop because
now you have two interfaces, induction coil to transfer disk, then
transfer disk to bottom of pot. It won't matter much when cooking food
in a smaller pot or pan but for the big brew kettle "watts into wort" is
all that counts.

Post by Derek J Decker
My induction burner has two control methods - heat to a controlled temp,
or run at a particular power. I can run the burner at its highest power
with an induction-compatible pot of water on it.

That would be the other issue I'd have to fix. Induction cooktops, for
whatever weird reason, cannot be brought into a mode where the
temperature can be set in 1F steps. They either have 40F steps or
ocasionally 10F steps. If you have to hold 157F that's not going to
work. Same for the fine line between rolling boil and boil-over. This is
where my old $12 Walmart work well. They have a nice old analog
thermostat knob where I put markers on the respective settings.
Amazingly, that holds 157F to +/-2F precision, measured with an external
sensor on a radio link.

So I was thinking, if the temperature sensing happens via an NTC or PTC
resistor under the ceramic layer I should be able to wire a
potentiometer in series for vernier control. Of course, nicely insulated
and all.

The engineers could do it smarter like the ones for my thermostat did.
When in normal mode it only offers five temps. Rare, medium-rare,
medium, and so on. It's a meat thermometer for barbecue. However, when
holding the temp-set button down for a few seconds it beeps, temp set
goes into blink mode and then I can increment/decrement the temperature
setting in 1F steps. Perfect to set the alarm for when I can put in my
steeping grains.

Post by Derek J Decker
If I use the disk with a non-compatible pot at full power, the disc will
overheat, and the burner will shut down till things cool off. The trick
when using the disk is to set the burner to maintain the highest possible
temperature (around 400°F is what I recall). This causes the burner to
modulate its power output and not overheat. 'Course, you're putting less
wattage into the pot than the burner could theoretically put out

That would make steeping control tough and, more importantly, require me
to be at the pot all the time later during the long initial boil.
Currently I brew outside and when it's 40mins until the first flavoring
hops go in I use that time to do some yard work, away from the pot, just
not too far away. So far I only had one boil-over, a very messy affair,
and that happened because I accidentally left the cooktops on max.

Post by Derek J Decker
Of course, if you're running two 1800 Watt devices at once, you'll want
them to be on separate circuits.

Oh yes, that's what I already do.

Post by Derek J Decker
1) Steel disk works, is a standard product you can buy for this
application
2) Disk goes under the pot, not inside

Many suggest a disk inside like here, for a more efficent heat tranfer:

https://www.ebay.com/itm/Stainless-Steel-Cookware-Thermal-Guide-Plate-Induction-Cooktop-Converter-Disk/123517389767

Yet I can't find any info on how much power you lose versus pot bottom
thickness.

I'd just need a much bigger disk and that I would have to cut myself.
I'd have to find a place in the valley that carries sheet stock of
stainless steel with enough magnetic property (IOW "the cheap stuff")
and go there with a magnet in my pocket to test. Cleaning the brew
kettle between brews would become more nasty though because first I'd
have to fish a big dripping steel plate out of the remaining sludge. I
could mount a small hook on it for that.

Post by Derek J Decker
3) Disk reduces efficiency some, overheating may result

Post by Joerg
Second question: If the power were the same how moch more efficient is
induction heating versus regular electric burners in your experience?

I could do controlled scientific experiments, but I haven't yet. I am of
the opinion that a higher percentage of the heat generated by induction
goes to the pot and not the surrounding air, etc

Just by gut feel, how much faster did it boil water that your electric
coils?

[Derek J Decker]

Post by Joerg

Post by Derek J Decker

Post by Joerg
Currently I am using two 1000W electric burners that my very wide
13-gallon aluminum brew kettle straddles. They plug into two different
circuits. My batches are 5-gallon and to make up for boil-off I start
with slightly above 5-1/2 gallons. 70F to 155F takes a whole hour,
155F to 207F boil takes more than another hour.
A few ideas a swirling around in my head on how to speed this up
without investing a ton of money. One of them is to buy two 120V
induction burners which come in 1800W, so more oomph. I'd probably set
them to 1500W in order not to overtax a circuit. Cost is about $50 a
piece. Of course, the aluminum pot would not work by itself and here
Does anyone know whether laying a big round steel disc inside the
kettle would make this work efficiently? Considering the thickness of
the aluminum bottom of the kettle the distance from the ceramic
cooktop surfaces to that plate could exceed 1/8".

I purchased an induction burner a few months ago because it was on sale
for $28 at Aldi - at that price, hey, new toy! And it works very well -
certainly boiled water faster than my electric coils.

$28, wow! Unfortunately we don't have Aldi in Northern California.

Aldi has good deals, but things that aren't food are not reliably stocked
- you'd have to catch one by chance anyway.

Post by Joerg

Post by Derek J Decker
But it didn't work with my copper-bottom Revereware pots, which limited
<https://www.amazon.com/gp/product/B07C2QTB3V/>
which is basically a stainless steel disk with a handle, and is built
precisely for this task. This goes under the pot you want to heat, and
not inside it - induction makes the disk hot, which makes your pot hot,
which boils the water. This is slightly less efficient than just
directly heating a compatible pot, but still works well.

From what I've read on the Internet the "under the pot" transfer plates
make things less efficient than the old electric coil cooktop because
now you have two interfaces, induction coil to transfer disk, then
transfer disk to bottom of pot. It won't matter much when cooking food
in a smaller pot or pan but for the big brew kettle "watts into wort" is
all that counts.

Yeah, and that loss of efficiency is why the disk overheats for me. Much
better to have an induction-ready brew kettle.

Post by Joerg

Post by Derek J Decker
My induction burner has two control methods - heat to a controlled
temp, or run at a particular power. I can run the burner at its
highest power with an induction-compatible pot of water on it.

That would be the other issue I'd have to fix. Induction cooktops, for
whatever weird reason, cannot be brought into a mode where the
temperature can be set in 1F steps. They either have 40F steps or
ocasionally 10F steps. If you have to hold 157F that's not going to
work. Same for the fine line between rolling boil and boil-over. This is
where my old $12 Walmart work well. They have a nice old analog
thermostat knob where I put markers on the respective settings.
Amazingly, that holds 157F to +/-2F precision, measured with an external
sensor on a radio link.
So I was thinking, if the temperature sensing happens via an NTC or PTC
resistor under the ceramic layer I should be able to wire a
potentiometer in series for vernier control. Of course, nicely insulated
and all.
The engineers could do it smarter like the ones for my thermostat did.
When in normal mode it only offers five temps. Rare, medium-rare,
medium, and so on. It's a meat thermometer for barbecue. However, when
holding the temp-set button down for a few seconds it beeps, temp set
goes into blink mode and then I can increment/decrement the temperature
setting in 1F steps. Perfect to set the alarm for when I can put in my
steeping grains.

I think the inexpensive induction cooktops use bang-bang control. I
recall some time ago thinking about induction for temp control during the
mash, and I found a site where some guy had torn apart his induction
burner, and found where to turn the thing on and off. He then arranged an
external PID loop controller for controlling temperature.

This is what you'd have to do - you want to control the temperature of
the wort, not the burner. If you want your wort at 157°F, the burner
will have to be slightly higher so that heat flows in to replace the heat
flow off the top of the pot. How much higher would take some fiddling,
it'd depend on the external temperatures...

Also with bang-bang control the burner is either on at full power or off
- so if you're running two, you should be sure your circuitry can handle
both at full power.

Post by Joerg

Post by Derek J Decker
If I use the disk with a non-compatible pot at full power, the disc
will overheat, and the burner will shut down till things cool off. The
trick when using the disk is to set the burner to maintain the highest
possible temperature (around 400°F is what I recall). This causes the
burner to modulate its power output and not overheat. 'Course, you're
putting less wattage into the pot than the burner could theoretically
put out

That would make steeping control tough and, more importantly, require me
to be at the pot all the time later during the long initial boil.
Currently I brew outside and when it's 40mins until the first flavoring
hops go in I use that time to do some yard work, away from the pot, just
not too far away. So far I only had one boil-over, a very messy affair,
and that happened because I accidentally left the cooktops on max.

Post by Derek J Decker
Of course, if you're running two 1800 Watt devices at once, you'll want
them to be on separate circuits.

Oh yes, that's what I already do.

Post by Derek J Decker
1) Steel disk works, is a standard product you can buy for this
application
2) Disk goes under the pot, not inside

https://www.ebay.com/itm/Stainless-Steel-Cookware-Thermal-Guide-Plate-

Induction-Cooktop-Converter-Disk/123517389767
I haven't seen inside-the-pot plates, I note that the description for
that one says it goes under the pot. I wonder about attenuation of the
operating magnetic fields through the aluminum bottom.

Post by Joerg
Yet I can't find any info on how much power you lose versus pot bottom
thickness.
I'd just need a much bigger disk and that I would have to cut myself.
I'd have to find a place in the valley that carries sheet stock of
stainless steel with enough magnetic property (IOW "the cheap stuff")
and go there with a magnet in my pocket to test. Cleaning the brew
kettle between brews would become more nasty though because first I'd
have to fish a big dripping steel plate out of the remaining sludge. I
could mount a small hook on it for that.

Post by Derek J Decker
3) Disk reduces efficiency some, overheating may result

Post by Joerg
Second question: If the power were the same how moch more efficient is
induction heating versus regular electric burners in your experience?

I could do controlled scientific experiments, but I haven't yet. I am
of the opinion that a higher percentage of the heat generated by
induction goes to the pot and not the surrounding air, etc

Just by gut feel, how much faster did it boil water that your electric
coils?

I have other things to do this afternoon, but I will stage a race and let
you know later

-Derek

[Joerg]

Post by Derek J Decker

Post by Joerg

Post by Derek J Decker

Post by Joerg
Currently I am using two 1000W electric burners that my very wide
13-gallon aluminum brew kettle straddles. They plug into two different
circuits. My batches are 5-gallon and to make up for boil-off I start
with slightly above 5-1/2 gallons. 70F to 155F takes a whole hour,
155F to 207F boil takes more than another hour.
A few ideas a swirling around in my head on how to speed this up
without investing a ton of money. One of them is to buy two 120V
induction burners which come in 1800W, so more oomph. I'd probably set
them to 1500W in order not to overtax a circuit. Cost is about $50 a
piece. Of course, the aluminum pot would not work by itself and here
Does anyone know whether laying a big round steel disc inside the
kettle would make this work efficiently? Considering the thickness of
the aluminum bottom of the kettle the distance from the ceramic
cooktop surfaces to that plate could exceed 1/8".

I purchased an induction burner a few months ago because it was on sale
for $28 at Aldi - at that price, hey, new toy! And it works very well -
certainly boiled water faster than my electric coils.

$28, wow! Unfortunately we don't have Aldi in Northern California.

Aldi has good deals, but things that aren't food are not reliably stocked
- you'd have to catch one by chance anyway.

Out here in the west it's either Walmart or Amazon. Ikea has one for $49.

Post by Derek J Decker

Post by Joerg

Post by Derek J Decker
But it didn't work with my copper-bottom Revereware pots, which limited
<https://www.amazon.com/gp/product/B07C2QTB3V/>
which is basically a stainless steel disk with a handle, and is built
precisely for this task. This goes under the pot you want to heat, and
not inside it - induction makes the disk hot, which makes your pot hot,
which boils the water. This is slightly less efficient than just
directly heating a compatible pot, but still works well.

From what I've read on the Internet the "under the pot" transfer plates
make things less efficient than the old electric coil cooktop because
now you have two interfaces, induction coil to transfer disk, then
transfer disk to bottom of pot. It won't matter much when cooking food
in a smaller pot or pan but for the big brew kettle "watts into wort" is
all that counts.

Yeah, and that loss of efficiency is why the disk overheats for me. Much
better to have an induction-ready brew kettle.

That gets expensive because I need a very wide kettle to straddle two
cooktops. 13-gallon tamale steamers which is what I have now are
generally aluminum.

Post by Derek J Decker

Post by Joerg

Post by Derek J Decker
My induction burner has two control methods - heat to a controlled
temp, or run at a particular power. I can run the burner at its
highest power with an induction-compatible pot of water on it.

That would be the other issue I'd have to fix. Induction cooktops, for
whatever weird reason, cannot be brought into a mode where the
temperature can be set in 1F steps. They either have 40F steps or
ocasionally 10F steps. If you have to hold 157F that's not going to
work. Same for the fine line between rolling boil and boil-over. This is
where my old $12 Walmart work well. They have a nice old analog
thermostat knob where I put markers on the respective settings.
Amazingly, that holds 157F to +/-2F precision, measured with an external
sensor on a radio link.
So I was thinking, if the temperature sensing happens via an NTC or PTC
resistor under the ceramic layer I should be able to wire a
potentiometer in series for vernier control. Of course, nicely insulated
and all.
The engineers could do it smarter like the ones for my thermostat did.
When in normal mode it only offers five temps. Rare, medium-rare,
medium, and so on. It's a meat thermometer for barbecue. However, when
holding the temp-set button down for a few seconds it beeps, temp set
goes into blink mode and then I can increment/decrement the temperature
setting in 1F steps. Perfect to set the alarm for when I can put in my
steeping grains.

I think the inexpensive induction cooktops use bang-bang control. I
recall some time ago thinking about induction for temp control during the
mash, and I found a site where some guy had torn apart his induction
burner, and found where to turn the thing on and off. He then arranged an
external PID loop controller for controlling temperature.

That is a good idea.

Post by Derek J Decker
This is what you'd have to do - you want to control the temperature of
the wort, not the burner. If you want your wort at 157°F, the burner
will have to be slightly higher so that heat flows in to replace the heat
flow off the top of the pot. How much higher would take some fiddling,
it'd depend on the external temperatures...

The old coil burner thermostats do that very nicely. I can turn one off
and set the other to my steeping marker, then walk away for 1/2h. At the
end it's usually still 156F, to within a couple of degrees. To my
surprise even on a windy day when there is a lot of heat loss on the
uninsulated aluminum pot.

Same for the boil which can almost be run unattended.

Post by Derek J Decker
Also with bang-bang control the burner is either on at full power or off
- so if you're running two, you should be sure your circuitry can handle
both at full power.

That's easy, just use opto-couplers and control both simultaneously.

[...]

Post by Derek J Decker

Post by Joerg

Post by Derek J Decker
1) Steel disk works, is a standard product you can buy for this
application
2) Disk goes under the pot, not inside

https://www.ebay.com/itm/Stainless-Steel-Cookware-Thermal-Guide-Plate-

Induction-Cooktop-Converter-Disk/123517389767
I haven't seen inside-the-pot plates, I note that the description for
that one says it goes under the pot. I wonder about attenuation of the
operating magnetic fields through the aluminum bottom.

In the picture they show it inside the pot. Finding out about the
attenuation is key, that's what I haven't figured out yet. Aluminum
doesn't attenuate the field much but the added distance does.

Post by Derek J Decker

Post by Joerg
Yet I can't find any info on how much power you lose versus pot bottom
thickness.
I'd just need a much bigger disk and that I would have to cut myself.
I'd have to find a place in the valley that carries sheet stock of
stainless steel with enough magnetic property (IOW "the cheap stuff")
and go there with a magnet in my pocket to test. Cleaning the brew
kettle between brews would become more nasty though because first I'd
have to fish a big dripping steel plate out of the remaining sludge. I
could mount a small hook on it for that.

Post by Derek J Decker
3) Disk reduces efficiency some, overheating may result

Post by Joerg
Second question: If the power were the same how moch more efficient is
induction heating versus regular electric burners in your experience?

I could do controlled scientific experiments, but I haven't yet. I am
of the opinion that a higher percentage of the heat generated by
induction goes to the pot and not the surrounding air, etc

Just by gut feel, how much faster did it boil water that your electric
coils?

I have other things to do this afternoon, but I will stage a race and let
you know later

Great! This is all really longterm. The old coil burners work, it's just
that making two beers plus clean-up takes all day that way. I turn on
the cooktops when I get up at 6:30am, do some office work, put in the
steeping grains at 7:30am, take a shower and so on, remove the grains at
8:00am and then walk the dogs while the wort heats up to boil. Rinse and
repeat for the noon session.

The real pain sets in when I have large late additions, for example
another 3lbs of malt syrup. Unless I preheat that upstairs in the
kitchen this requires another 20mins or so to get back to boil. Which
can turn earlier flavoring hops partially into bittering hops.

[Derek J Decker]

Post by Joerg

Post by Derek J Decker
I have other things to do this afternoon, but I will stage a race and
let you know later

Great! This is all really longterm. The old coil burners work, it's just
that making two beers plus clean-up takes all day that way. I turn on
the cooktops when I get up at 6:30am, do some office work, put in the
steeping grains at 7:30am, take a shower and so on, remove the grains at
8:00am and then walk the dogs while the wort heats up to boil. Rinse and
repeat for the noon session.
The real pain sets in when I have large late additions, for example
another 3lbs of malt syrup. Unless I preheat that upstairs in the
kitchen this requires another 20mins or so to get back to boil. Which
can turn earlier flavoring hops partially into bittering hops.

OK, I did some experiments. All of these are times to bring 2 cups of
water to a full rolling boil:

6 inch burner, 1325 watts : 5:10
8 inch burner, 2350 watts : 3:55

1800 watt induction, compatible pot,
full power : 2:10
temp control at 464: 3:20

1800 watt induction, incompatible pot,
steel disc, control at 464: >12 minutes (I gave up)
steel disc, full power: Unit overheats and shuts down

Really, to get all the benefits of the induction burner, you need a
compatible pot.

Googling for 'induction homebrew', 'induction sous vide', and 'induction
PID' brings up a number of interesting things. Cuisinart makes an
induction burner that will pair with a bluetooth thermometer to control
the fluid temp in a pot directly:

<https://www.tastyonetop.com/>

It's controlled by a smartphone app, and I hear the app stinks, but eh.

There ya go

-Derek

[Joerg]

Post by Derek J Decker

Post by Joerg

Post by Derek J Decker
I have other things to do this afternoon, but I will stage a race and
let you know later

Great! This is all really longterm. The old coil burners work, it's just
that making two beers plus clean-up takes all day that way. I turn on
the cooktops when I get up at 6:30am, do some office work, put in the
steeping grains at 7:30am, take a shower and so on, remove the grains at
8:00am and then walk the dogs while the wort heats up to boil. Rinse and
repeat for the noon session.
The real pain sets in when I have large late additions, for example
another 3lbs of malt syrup. Unless I preheat that upstairs in the
kitchen this requires another 20mins or so to get back to boil. Which
can turn earlier flavoring hops partially into bittering hops.

OK, I did some experiments. All of these are times to bring 2 cups of
6 inch burner, 1325 watts : 5:10
8 inch burner, 2350 watts : 3:55

When interpolating that would come to about 4:30 if it was an 1800W burner.

Post by Derek J Decker
1800 watt induction, compatible pot,
full power : 2:10
temp control at 464: 3:20

This is impressive. Assuming the above interpolated value that means
about twice as fast. I wonder why it slowed down so much under temp
control. Maybe the cooktop throttles down when it gets close.

Post by Derek J Decker
1800 watt induction, incompatible pot,
steel disc, control at 464: >12 minutes (I gave up)
steel disc, full power: Unit overheats and shuts down
Really, to get all the benefits of the induction burner, you need a
compatible pot.

That's a problem because at reasonable cost there aren't any compatible
pots wide enough to straddle two cooktops, only aluminum. A large steel
dsik in there should work if the distance due to the thickness of the
aluminum bottom isn't ruining the coupling.

Post by Derek J Decker
Googling for 'induction homebrew', 'induction sous vide', and 'induction
PID' brings up a number of interesting things. Cuisinart makes an
induction burner that will pair with a bluetooth thermometer to control
<https://www.tastyonetop.com/>
It's controlled by a smartphone app, and I hear the app stinks, but eh.

That is a good solution. They don't say whether temp control is in 1F
increments but the video indicates it may be. I'd have to build a new
thermistor probe because the furnished one is too tiny for a brew
kettle. If it's just an NTC or PTC resistor probe that would be easy.

Quite pricey at $149 but an option might be to use only one Cuisinart
cooktops and then another regular one that isn't precisely controlled.
The regular cooktop would be just to pump in power during heat-up. I can
turn that off during steeping and reduce its power during the boil. One
of them would have to get a spacer underneath to bring both to the same
height but that is easy.

It does have its quirks though.

https://www.wired.com/review/tasty-one-top-smart-induction-cooktop/

Quote "... the burner LEDs started blinking in the middle of a batch and
clearly something was wrong, because the temperature started plummeting.
Reading the FAQs later, I learned that this is a safety feature that
kicks in if the cooktop is above 214 degrees Fahrenheit for more than 45
minutes; you just press the plus button on the One Top and keep
cooking". That's an inconvenience for brewers. Hmm, maybe hacking a
conventional induction cooktop is the better option.

Post by Derek J Decker
There ya go

Thanks! Very helpful

[Derek J Decker]

Post by Joerg

Post by Derek J Decker
6 inch burner, 1325 watts : 5:10
8 inch burner, 2350 watts : 3:55

When interpolating that would come to about 4:30 if it was an 1800W burner.

Post by Derek J Decker
1800 watt induction, compatible pot,
full power : 2:10
temp control at 464: 3:20

This is impressive. Assuming the above interpolated value that means
about twice as fast. I wonder why it slowed down so much under temp
control. Maybe the cooktop throttles down when it gets close.

The cooktop throttles down to keep the temp at 464. The entire disk (A
steel-aluminum-steel sandwich) gets hot, but only part of it is covered
by the pot. The thermal connection between the pot and disk isn't great
- it's an older pot and a little wobbly on the very flat disk.

I could fix all those things, but I'm not sure how much it would help.

I did another experiment - I laid a sheet of aluminum foil on top of the
inductive burner, then placed a inductive-compatible pot on top with some
water. One layer of foil worked. Two layers of foil worked if I
smoothed them together.

4 layers of foil, though, made the burner complain there wasn't a
compatible pot. YMMV.

Post by Joerg

Post by Derek J Decker
1800 watt induction, incompatible pot,
steel disc, control at 464: >12 minutes (I gave up)
steel disc, full power: Unit overheats and shuts down
Really, to get all the benefits of the induction burner, you need a
compatible pot.

That's a problem because at reasonable cost there aren't any compatible
pots wide enough to straddle two cooktops, only aluminum. A large steel
dsik in there should work if the distance due to the thickness of the
aluminum bottom isn't ruining the coupling.

Granite wear, which is thin steel with a thin enamel layer, is compatible
with induction burners, comes in large sizes, and is pretty cheap. It's
usually black with white speckles.

Granite wear is what I use for brew kettles here.

Hmm, looking on their site, their biggest pot is a 33 quart crab/crawfish
cooker. maybe not

Post by Joerg

Post by Derek J Decker
Googling for 'induction homebrew', 'induction sous vide', and
'induction PID' brings up a number of interesting things. Cuisinart
makes an induction burner that will pair with a bluetooth thermometer
<https://www.tastyonetop.com/>
It's controlled by a smartphone app, and I hear the app stinks, but eh.

That is a good solution. They don't say whether temp control is in 1F
increments but the video indicates it may be. I'd have to build a new
thermistor probe because the furnished one is too tiny for a brew
kettle. If it's just an NTC or PTC resistor probe that would be easy.
Quite pricey at $149 but an option might be to use only one Cuisinart
cooktops and then another regular one that isn't precisely controlled.
The regular cooktop would be just to pump in power during heat-up. I can
turn that off during steeping and reduce its power during the boil. One
of them would have to get a spacer underneath to bring both to the same
height but that is easy.
It does have its quirks though.
https://www.wired.com/review/tasty-one-top-smart-induction-cooktop/
Quote "... the burner LEDs started blinking in the middle of a batch and
clearly something was wrong, because the temperature started plummeting.
Reading the FAQs later, I learned that this is a safety feature that
kicks in if the cooktop is above 214 degrees Fahrenheit for more than 45
minutes; you just press the plus button on the One Top and keep
cooking". That's an inconvenience for brewers. Hmm, maybe hacking a
conventional induction cooktop is the better option.

Or (for a big pot) two inductive burners for moving temperature in the
pot rapidly, and one electric with a cheap PID controller for maintaining
mash temp, possibly maintaining boil. Cheaper, reliable, but you have to
fit all those burners under there....

Post by Joerg

Post by Derek J Decker
There ya go

Thanks! Very helpful

[Joerg]

Post by Derek J Decker

Post by Joerg

Post by Derek J Decker
6 inch burner, 1325 watts : 5:10
8 inch burner, 2350 watts : 3:55

When interpolating that would come to about 4:30 if it was an 1800W burner.

Post by Derek J Decker
1800 watt induction, compatible pot,
full power : 2:10
temp control at 464: 3:20

This is impressive. Assuming the above interpolated value that means
about twice as fast. I wonder why it slowed down so much under temp
control. Maybe the cooktop throttles down when it gets close.

The cooktop throttles down to keep the temp at 464. The entire disk (A
steel-aluminum-steel sandwich) gets hot, but only part of it is covered
by the pot. The thermal connection between the pot and disk isn't great
- it's an older pot and a little wobbly on the very flat disk.
I could fix all those things, but I'm not sure how much it would help.
I did another experiment - I laid a sheet of aluminum foil on top of the
inductive burner, then placed a inductive-compatible pot on top with some
water. One layer of foil worked. Two layers of foil worked if I
smoothed them together.
4 layers of foil, though, made the burner complain there wasn't a
compatible pot. YMMV.

Oh, that's bad news. Since the bottom of my pot is way thicker than four
layers of foil it wouln't work with a disk inside.

Post by Derek J Decker

Post by Joerg

Post by Derek J Decker
1800 watt induction, incompatible pot,
steel disc, control at 464: >12 minutes (I gave up)
steel disc, full power: Unit overheats and shuts down
Really, to get all the benefits of the induction burner, you need a
compatible pot.

That's a problem because at reasonable cost there aren't any compatible
pots wide enough to straddle two cooktops, only aluminum. A large steel
dsik in there should work if the distance due to the thickness of the
aluminum bottom isn't ruining the coupling.

Granite wear, which is thin steel with a thin enamel layer, is compatible
with induction burners, comes in large sizes, and is pretty cheap. It's
usually black with white speckles.

Ah, the pots I saw in my grandparent's homes.

Post by Derek J Decker
Granite wear is what I use for brew kettles here.
Hmm, looking on their site, their biggest pot is a 33 quart crab/crawfish
cooker. maybe not

That would not likely be wide enough. Width is the key to straddle two
burners and just about the only way to brew with electrical power in the
US. Unless you are willing to shell out big bucks for a restaurant grade
240V cooktop and run a cable or install an immersion heater element in
the brew pot. The latter would make it nearly impossible to stir in DME
and is hard to clean. If DME clumps up on there it can make the beer
taste funky.

Post by Derek J Decker

Post by Joerg

Post by Derek J Decker
Googling for 'induction homebrew', 'induction sous vide', and
'induction PID' brings up a number of interesting things. Cuisinart
makes an induction burner that will pair with a bluetooth thermometer
<https://www.tastyonetop.com/>
It's controlled by a smartphone app, and I hear the app stinks, but eh.

That is a good solution. They don't say whether temp control is in 1F
increments but the video indicates it may be. I'd have to build a new
thermistor probe because the furnished one is too tiny for a brew
kettle. If it's just an NTC or PTC resistor probe that would be easy.
Quite pricey at $149 but an option might be to use only one Cuisinart
cooktops and then another regular one that isn't precisely controlled.
The regular cooktop would be just to pump in power during heat-up. I can
turn that off during steeping and reduce its power during the boil. One
of them would have to get a spacer underneath to bring both to the same
height but that is easy.
It does have its quirks though.
https://www.wired.com/review/tasty-one-top-smart-induction-cooktop/
Quote "... the burner LEDs started blinking in the middle of a batch and
clearly something was wrong, because the temperature started plummeting.
Reading the FAQs later, I learned that this is a safety feature that
kicks in if the cooktop is above 214 degrees Fahrenheit for more than 45
minutes; you just press the plus button on the One Top and keep
cooking". That's an inconvenience for brewers. Hmm, maybe hacking a
conventional induction cooktop is the better option.

Or (for a big pot) two inductive burners for moving temperature in the
pot rapidly, and one electric with a cheap PID controller for maintaining
mash temp, possibly maintaining boil. Cheaper, reliable, but you have to
fit all those burners under there....

Induction burners are generally large. Even the regular ones are big and
three won't fit. Of course, I could try to find a large ceramic plate
from a discarded induction range (hard to find), cut it down and mount
all the induction coils underneath in close proximity. That becomes a
larger project though.

[Baloonon]

Post by Joerg
That would make steeping control tough and, more importantly, require
me to be at the pot all the time later during the long initial boil.
Currently I brew outside and when it's 40mins until the first
flavoring hops go in I use that time to do some yard work, away from
the pot, just not too far away. So far I only had one boil-over, a
very messy affair, and that happened because I accidentally left the
cooktops on max.

If you're talking about steeping stuff like crystal malt, that typically
can be done in a fraction of the water in something like a cooler or large
thermos. If you're heating a lot of water, it ought to be possible to pull
off, say, a couple of quarts at the lower steeping/mashing temperature,
keep the grain/water mix in a thermos or cooler to maintain temperature,
and by the time the water has come to a boil just add it back in to the
main pot. Ovens are good for maintaining temps too if you're just talking
about a half gallon or so.

Post by Joerg
I'd have to find a place in the valley that carries sheet stock of
stainless steel with enough magnetic property (IOW "the cheap stuff")
and go there with a magnet in my pocket to test.

You'd just want to make sure it's food grade if it's going inside the pot.

[Joerg]

Post by Baloonon

Post by Joerg
That would make steeping control tough and, more importantly, require
me to be at the pot all the time later during the long initial boil.
Currently I brew outside and when it's 40mins until the first
flavoring hops go in I use that time to do some yard work, away from
the pot, just not too far away. So far I only had one boil-over, a
very messy affair, and that happened because I accidentally left the
cooktops on max.

If you're talking about steeping stuff like crystal malt, that typically
can be done in a fraction of the water in something like a cooler or large
thermos. If you're heating a lot of water, it ought to be possible to pull
off, say, a couple of quarts at the lower steeping/mashing temperature,
keep the grain/water mix in a thermos or cooler to maintain temperature,
and by the time the water has come to a boil just add it back in to the
main pot. Ovens are good for maintaining temps too if you're just talking
about a half gallon or so.

I am a lowly extract brewer, mostly due to time constraints and even
more so for lack of space. For many beers I have to steep in special
grains, usually between 1/2lbs and 2lbs.

My main thing is boil control though. The simple bi-metal thermostats on
the cheap electric coil burners do that quite well. I'd just like to
have more oomph than 2000W.

Post by Baloonon

Post by Joerg
I'd have to find a place in the valley that carries sheet stock of
stainless steel with enough magnetic property (IOW "the cheap stuff")
and go there with a magnet in my pocket to test.

You'd just want to make sure it's food grade if it's going inside the pot.

Good point. Though I am wondering whether my American but Made-in-China
stainless steel fermenters are 100% kosher. There were the occasional
rust spots and in the beginning I had to scrub out black polishing paste
until no more came off. Though that also goes for lots of not very
high-falutin pots and pans.

[Baloonon]

Post by Joerg

Post by Baloonon

Post by Joerg
That would make steeping control tough and, more importantly,
require me to be at the pot all the time later during the long
initial boil. Currently I brew outside and when it's 40mins until
the first flavoring hops go in I use that time to do some yard work,
away from the pot, just not too far away. So far I only had one
boil-over, a very messy affair, and that happened because I
accidentally left the cooktops on max.

If you're talking about steeping stuff like crystal malt, that
typically can be done in a fraction of the water in something like a
cooler or large thermos. If you're heating a lot of water, it ought
to be possible to pull off, say, a couple of quarts at the lower
steeping/mashing temperature, keep the grain/water mix in a thermos
or cooler to maintain temperature, and by the time the water has come
to a boil just add it back in to the main pot. Ovens are good for
maintaining temps too if you're just talking about a half gallon or
so.

I am a lowly extract brewer, mostly due to time constraints and even
more so for lack of space. For many beers I have to steep in special
grains, usually between 1/2lbs and 2lbs.
My main thing is boil control though. The simple bi-metal thermostats
on the cheap electric coil burners do that quite well. I'd just like
to have more oomph than 2000W.

For what it's worth, to save some time and effort on brew day, steeping
can be done in advance and the liquid can be stored in the fridge or
even freezer. Obviously adding cold liquid will slow down the boil a
bit, but if you're only talking 10% or less of the total amount of
liquid, it shouldn't be too much.

Post by Joerg

Post by Baloonon

Post by Joerg
I'd have to find a place in the valley that carries sheet stock of
stainless steel with enough magnetic property (IOW "the cheap
stuff") and go there with a magnet in my pocket to test.

You'd just want to make sure it's food grade if it's going inside the pot.

Good point. Though I am wondering whether my American but
Made-in-China stainless steel fermenters are 100% kosher. There were
the occasional rust spots and in the beginning I had to scrub out
black polishing paste until no more came off. Though that also goes
for lots of not very high-falutin pots and pans.

This looks like a pretty solid study on metals leaching out of stainless
steel cookware, although I am definitely not qualified to interpret it
in any detail.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284091/

One thing I noticed though is that leaching tends to go down over time,
so it's possible it's not something to worry about any longer....

[Joerg]

Post by Baloonon

Post by Joerg

Post by Baloonon

Post by Joerg
That would make steeping control tough and, more importantly,
require me to be at the pot all the time later during the long
initial boil. Currently I brew outside and when it's 40mins until
the first flavoring hops go in I use that time to do some yard work,
away from the pot, just not too far away. So far I only had one
boil-over, a very messy affair, and that happened because I
accidentally left the cooktops on max.

If you're talking about steeping stuff like crystal malt, that
typically can be done in a fraction of the water in something like a
cooler or large thermos. If you're heating a lot of water, it ought
to be possible to pull off, say, a couple of quarts at the lower
steeping/mashing temperature, keep the grain/water mix in a thermos
or cooler to maintain temperature, and by the time the water has come
to a boil just add it back in to the main pot. Ovens are good for
maintaining temps too if you're just talking about a half gallon or
so.

I am a lowly extract brewer, mostly due to time constraints and even
more so for lack of space. For many beers I have to steep in special
grains, usually between 1/2lbs and 2lbs.
My main thing is boil control though. The simple bi-metal thermostats
on the cheap electric coil burners do that quite well. I'd just like
to have more oomph than 2000W.

For what it's worth, to save some time and effort on brew day, steeping
can be done in advance and the liquid can be stored in the fridge or
even freezer. Obviously adding cold liquid will slow down the boil a
bit, but if you're only talking 10% or less of the total amount of
liquid, it shouldn't be too much.

I could do that but it wouldn't save time, just move it to another day.
Mostly I do not have that previous day available. I am trying to work
other chores into brew day so the wait times can be occupied. Ok,
occasionally watching a Western :-)

Post by Baloonon

Post by Joerg

Post by Baloonon

Post by Joerg
I'd have to find a place in the valley that carries sheet stock of
stainless steel with enough magnetic property (IOW "the cheap
stuff") and go there with a magnet in my pocket to test.

You'd just want to make sure it's food grade if it's going inside the pot.

Good point. Though I am wondering whether my American but
Made-in-China stainless steel fermenters are 100% kosher. There were
the occasional rust spots and in the beginning I had to scrub out
black polishing paste until no more came off. Though that also goes
for lots of not very high-falutin pots and pans.

This looks like a pretty solid study on metals leaching out of stainless
steel cookware, although I am definitely not qualified to interpret it
in any detail.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284091/
One thing I noticed though is that leaching tends to go down over time,
so it's possible it's not something to worry about any longer....

Oh, oh, I should be dead by now ...

I don't boil in the fermenters even though they are rated for that. Each
has seen north of 40 brews so I guess it's all stabilized by now. I
cleaned them very well before first use. The fermenters never get much
rest, maximum one day.