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Stovetop Temperature Controller Hack

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This is a Zero Delta T cooking breakthrough. You've seen other Sous Vide stories, but you've never seen anything like this. Because there is so very little to see: Almost all of the gadgetry is eliminated.

To do this yourself, you will need a love of fine food and a sound understanding of electrical wiring. Materials needed are an old-fashioned non-computerized electric range, a temperature controller, a scrap electric cord with plug, and household electrical kit. 
 
 
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Step 2: Identify The Right Wires

It would probably be best to continue by cleaning the stovetop. You know it needs it. Your mother will be proud of you. And you certainly don't want to look like a slob taking pictures of this hack.

Now, lift the stove deck and identify the unique color of the wires feeding the target burner. These happen to be blue. That's it: Close it up, you're done here. The burner should not be modified in any way.


Step 3: Access The Infinity Switch

The burner controls can usually be accessed by disconnecting the panel they are mounted on. Mine was held with 5 screws. Infinity switches do fail on occasion. They are standardized and designed to be easily replaced. Wiring diagrams and diagnostic guides are available online if your stove documentation is missing.

My object was not to replace the switch, but completely disconnect it from the stove power supply. I also disconnected the switch from the indicator light, which was tied to the adjacent switch. The blue wire electrical connections between the burner and switch stay put.



how do you make yogurt with it? I have tried once to make yogurt and failed.
flavrt (author)  PyromaniacDaniel11 months ago
Got you covered, Daniel. Head over to the Yogurt Department.

And stay safe out there.
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lperkins1 year ago
With a bit more effort, you could add a switch and a socket to the stove and be able to use the burner in either mode whenever you wanted.


flavrt (author)  lperkins1 year ago
Yes! I could have added an iPod jack, sound sound speakers, a flat panel TV, and wifi to be able to use my stove in entertainment mode too. With a bit more effort. But trying to switch circuits with different voltages on a burner sounds difficult, costly, dangerous, irreversible, and unnecessary.

None the less, you may have a great idea. I will keep an open mind until you publish an Instructable that shows how you did it.
I may well be doing something like this as part of another project once the budget allows me to continue working on it. I'll be sure to take plenty of pictures for you.

The 240 volts used by the stove burner is made up of two 120 volt feeds. How safe and easy a switch would be depends on whether the stove has any 120 volt components. If it does, then you find a 3 pole switch capable of running the burner and set it to swap one of those feeds for the neutral wire used by the 120 volt stuff. Presto, your burner is switchable and it's only one switch so you won't short anything. You'll even be able to change it while the burner is running if you like. Use the high voltage to get your stuff up to temperature and then turn it down to let is simmer. If your stove doesn't have 120 volt components then you might need to hunt around a bit to find the neutral wire (if there even is one.)

The connection for the external thermostat uses another 3-pole switch and an electrical socket (I recommend getting one of the varieties that doesn't match common appliances so nobody has any accidents.) Switch one way goes straight to the burner, switch the other way goes to the socket where you can attach whatever kind of switching mechanism you like from a thermostat to a push-button. The advantage here is that you can easily disconnect all the trailing wires when you're not using it so nobody accidentally turns on the wrong burner and melts anything (and, if they do, you don't have to take the stove apart again to replace it.) And, again, you can switch between the two at will, while it's running.

I wouldn't recommend turning your stove into an entertainment center. Distractions while cooking usually have bad results in my experience. ;)
cody3051 year ago
1. I'm not sure what I'm looking at. Is the heating element and the temp sensor both inserted into the water bath? Could the temp sensor fall out or conk out and cause runaway heating of the water?
2. I agree with you about the temperature consistency of the water. As we all know, heat rises, so there will automatically be circulation from the heated water to the unheated water, which will rapidly equalize and maintain the temperature.
flavrt (author)  cody3051 year ago
"I'm not sure what I'm looking at."

That's a key problem with this Instructable: There isn't much to see. It is a method for converting a stove back burner to a builtin hot plate. Now we can have the control options that are commonly available for 120v countertop appliances, plus the safety, convenience, durability, and efficiency of a stovetop platform.

"Is the heating element and the temp sensor both inserted into the water bath?"

No, but I can see how the 1st image may be misleading. That was my trial run, and does not represent typical operation with a closed pot. Heat come only from the stove burner beneath the pot. One temperature probe from the controller goes into the water bath. Sometimes I put another directly into the food -- a jug of milk for example.

"Could the temp sensor fall out or conk out and cause runaway heating of the water? "

Since this is an unattended heating process, it's good to look at every failure mode with can find. The worst case scenario is an overnight run where the failure occurs right after bedtime. The range infinity switch and the temperature controller are both designed to fail safely.

- If there is a blackout, or the range fails, or the controller fails, I wake up to a cold water bath and throw out the food.

- If the power blinks, the controls keep their original setting. The process continues as though it were never interrupted.

- If the power fails before the food is pasteurized, and lasts long enough to grow dangerous amounts of pathogens, and then comes back on for less time than needed to pasteurize the food again, there could be trouble. So it may be prudent to plug a timer into the same outlet as the controller to measure the actual processing time. Or just toss any food that has been subjected to a power failure during an overnight process.

It is also possible for the temperature probe to fall out of the pot. Since the wire is stiff and the hole is small and there is no movement, this is very unlikely. But it certainly could cause runaway heating. This is why I incorporated the stove infinity switch into the circuit. By using 120v power and dialing down the current into the burner for long controlled heating cycles, the pot can not boil dry with continuous uncontrolled 30 watt heating overnight .

I'm going to amend the Instructable to highlight your point about runaway heating. Thank you.
While this is an elegant solution, it won't produce true sous vide cooking control because it still relies purely on convection to move the heat from the bottom of the pot to the top. That means considerable differences in heat and cooking in different parts of the pot.

Temperature control is only part of the sous vide. The other part is pumped circulation that makes the temperature near perfectly even in all parts of the cooking vessel. This in turn means fewer temperature gradients inside the food.




flavrt (author)  shannonlove1 year ago
Thank you very much for a thought provoking comment. Let's look at your complaint about "true sous vide" from several perspectives.

1) Zero Delta T cooking is the cornerstone of Modernist Cuisine. Widely heralded as a great break with culinary tradition, I am amused to view the sanctification Moderist dogma. As The Who taught us with We Won't Be Fooled Again, hypocrisy is baked into all revolutions.

2) There is no mention of vacuum in this Instructable. The only place I used the phrase "sous vide" is in the very 1st paragraph. This was to highlight my process as something different from sous vide.

I wrote: "This is a Zero Delta T cooking breakthrough." So you are objecting to a literary object that only occurred in your mind.

3) "... it still relies purely on convection to move the heat from the bottom of the pot to the top. That means considerable differences in heat and cooking in different parts of the pot."

This is false in every way. At cooking temperature. 99% of the heat flux occurs with *conduction* through the sides of the pot to the surrounding air. As the water bath approaches the target temperature, the pot behaves as an insulator and stops heating the water. Then the food is put into the bath. Virtually no convection can develop by applying 25 watts of heat to 20 pounds of water at that point, because there is a vanishing temperature gradient in the water. Conduction through the water takes care of the rest.

The proof is in the illustrated results: There is no visual or tactile gradient in the protein until the surface is torch seared.

4) "Temperature control is only part of the sous vide."

Herein lies the fundamental problem with "sous vide." Cooking cannot occur "under vacuum." This process generates between 1000 to 2000 pascals of cooking pressure on the food. Whatever you decree in your kingdom to be an essential part of Sous Vide, time and temperature control are the *only* elements that matter to real food. Any vacuum that can be created in the cooking bag is instantly negated by evaporating water, which actually cools the food. So what you think is vacuum cooking is really vacuum cooling followed by pressure cooking from the weight of the water bath.

5) I think it is distracting from the topic of this Instructable, but water bath circulation is interesting to me. I used circulators in the chemistry lab to regulate reactions within 0.1ºC. Circulators are also useful in commercial kitchens where large amounts of heat need to be transfered, in order to serve large amounts of protein in a hurry. Contrarily, circulators have no place in the home kitchen, which is clearly the topic at hand. In this setting, circulators serve no purpose other than creating a barrier to this otherwise very practical cooking method.

6) Unattended electric cords and water hoses running across energized stovetops are failure points and serious safety hazards. We want simpler, cheaper, more reliable, more effective processes. Therefore, I strong recommend against using circulators with my design.
Hmmmm, are you sure meant to reply to me for all of that? I am bit confused because...

1) Zero Delta T cooking is the cornerstone of Modernist Cuisine. Widely heralded...

I have no clue what "Zero Delta T cooking" is and have never heard the phrase until I read this instructable. Nearly 30 years child and adult in the sciences and tech industry has trained me to blow past phrases like that as marketing gibberish. I just look at the tech. 

My knowledge of sous vide comes from (A) watching hundreds of hours of the Food network with my foodie spouse and (B) using immersion circulators in the lab. 

2) There is no mention of vacuum in this Instructable.

True and I didn't mention it either. 

The only place I used the phrase "sous vide" is in the very 1st paragraph. This was to highlight my process as something different from sous vide.

Well no. In the version I read you wrote, "You've seen other Sous Vide stories, but you've never seen anything like this." Meaning this instructable is a Sous Vide Story. I used that as my conceptual starting point. 

At cooking temperature. 99% of the heat flux occurs with *conduction* through the sides of the pot to the surrounding air.

Doesn't actually matter. The point is without forced circulation, you get temperature gradients. It might not matter on something with a large thermal mass like a pork lion but if you do something more delicate like a sliced vegetable it probably will. 

But, nothing beats empirical results so your nicely cooked loin trumps my theory. You could test my hypothesis my moving the probe around and while recreating the same conditions each time. I think you will find gradients both from below to above and then from the center to the outside. There's a reason forced circulation was used in the lab in the first place. 

Whatever you decree in your kingdom to be an essential part of Sous Vide, time and temperature control are the *only* elements that matter to real food. Any vacuum that can be created in the cooking bag is instantly negated by evaporating water, which actually cools the food

Not sure who've you've been reading and/or arguing against but using a vacuum to evacuate air from the sealed bags as nothing to do with pressure on the food. It removes the air so the air pockets won't form an irregular insulating layer across the food which would defeat the goal of even cooking. Water vapor arising during cooking is smaller, more symmetrically distributed, more thermally conductive and unavoidable in any case. 

I'm not interested marketing rhetoric but the I would argue the essence of sous vide is thermal consistency across every point of the surface of the immersed object. Every part of an immersion circulator is aimed at that accomplishing that. Forced circulation is vital to that thermal consistency. 

Contrarily, circulators have no place in the home kitchen, which is clearly the topic at hand. In this setting, circulators serve no purpose other than creating a barrier to this otherwise very practical cooking method.

That is a matter of opinion. Strictly speaking, all you need to cook is fire, a stick and tons of experience and skill.

As I said, it depends on what you cook. If you cook things with low thermal mass, then forced circulation becomes necessary. It is also very useful for developing recipes and examining the role of heat at different stages of a recipes' development.

It also depends on the person eating and evaluating. I can hardly tell a properly cooked piece of steak from a piece of charcoal it was cooked on but I would wager a considerable sum that my spouse in a blind taste test could discern the difference between a pork lion cooked in your device from one cooked in a high dollar sous vide. 

If you want to criticize dogmatism in others, you first have to start with the eliminating as much subjectivity from your own thinking and arguments as possible. 

I don't like marketing babble but well known labels create expectations. Let's put it this way: If you tried to market your device as a "sous vide" you could probably be successfully sued for deceptive trade practices.

If you want to argue that your device, in a real world home kitchen with real world food, produces enough thermal consistency that the vast majority of people can't tell the difference between food cooked in it and one cooked in device legally marketed as "sous vide", I certainly won't quibble. Nothing beats empirical evidence (but i'd like to see a broad range of foods cooked in it before I'd really sign off on it.)

However, if some individual naive about sous vide mistook this for an actual sous vide, not knowing devices that are called "sous vide" have forced circulation, then my comment was intended to correct that misperception.

6) Unattended electric cords and water hoses running across energized stovetops are failure points and serious safety hazards. We want simpler, cheaper, more reliable, more effective processes. Therefore, I strong recommend against using circulators with my design.

Agreed, again I just wanted to point out that this design excluded forced circulation. Whether that is actually an exclusion of any real world consequence for most people is largely subjective but still the exclusion needed to be pointed out because the phrase "sous vide" carries with it the expectation of forced circulation. 

 Lastly,  beware of "inventors hubris." When you create something, especially a profoundly elegant and successful design such as this, it can trigger a strong emotional attachment and a fierce protectiveness almost as if it were a child. I have done it myself. Technological history is a hobby of mine and it is shocking how many great inventors were done in by their own egos fed by their very real successes. All the greats were hurt by it. It destroyed many so soon that only historians know their names.

Not that you're anywhere close to that, of course, but your obvious passion for the device seems (in my subjective opinion) to be pushing you towards the intemperate. For example, you seem to be in some kind of theoretical or rhetorical debate with the "Zero Delta T" advocates but you got so involved that you forgot that the fast majority of people reading this instructable have no knowledge of that debate and probably don't care. 

Just a bit of unsolicited advice from the experience of my own mistakes. 
flavrt (author)  shannonlove1 year ago
This isn't an Instructable on psychoanalysis. Beyond unsolicited, your ad hominem is off-topic and inappropriate. It was my mistake responding to antithetical comments. I promise it won't happen again.
trhoresh1 year ago
Nice 'able! I'm going to seriously consider this for my second attempt at home brewing. The first go around with an all grain mash saw a lot of temperature fluctuation. It's a fairly tight temp range for the mash and twisting the knob back and forth on a normal electric stovetop certainly wasn't precise enough.
flavrt (author)  trhoresh1 year ago
I feel your pain. My kitchen is so miserable, I can't bear to hang around watching food cook.

Here is something else to consider. Approach your taget temperature from below. If it is at all possible, cook your mash within a water bath. Even if is just a jacket of water between pots. And put a tea towel on top of the pot lid. You will always be more effective in stabilizing temperature by controlling heat loss rather than fidgeting with heat gain. The magic in low-temp cooking is the thermal mass of the water.

The great lesson of Building Science is making living space comfortable with more insulation and less ductwork.
You failed to mention what a Dork is. The word has many slang connotations but that doesn't seem to apply to this.
flavrt (author)  random squigles1 year ago
"You failed to mention what a Dork is."

Well compromise can lead to failure, so let's deal with it. In my kitchen, dorking is a verb used as shorthand for Zero Delta T cooking. I don't work for DorkFood. Though I dearly love their product, it's not my job to advertise for them. This is for the benefit of Instructables participants, so my intent was to emphasize that this design was not dependent on any proprietary gear. Many Instructables have been published which employ other manufactured temperature controllers. And there are those showing how to build them from generic components. They can all be used in this stovetop hack, and may be better than the Dork. I'm here for the food, not the electronics.

That said, I did illustrate my Dork 4 times and labeled it twice. But sometimes that's not enough. It's a box available for $99 from Amazon. It regulates the flow of 110v current to an outlet, based on the temperature you set and the temperature it detects, in the most delightful way.
rshortt1 year ago
Great idea.

You could also wire this to a cheap $10 - $15 110v single element hot plate.
flavrt (author)  rshortt1 year ago
Thanks.

I tried to address the use of hot plates, etc. in Step #6. There are safety and durability issues in my mind with countertop heating appliances. Often these cooking projects go overnight or several days. I'll rarely low-temp cook anything for less than 4 hours, because I want to kill pathogens dead. In any case, I don't want hang around the kitchen and don't want to worry when I'm gone or sleeping. The relatively mighty construction of the stove gets me there.
jarikcbol1 year ago
You had me at Sous Vide.
flavrt (author)  jarikcbol1 year ago
It's great to have you.

I'm trying move toward the term "Zero Delta T." At this point in the popularization of Modernist Cuisine, Sous Vide seems to be causing too much confusion. I'll go into this more.
Awesome, I performed a similar hack just last week! Difference being that I left the original functionality of the burner intact by splicing my new cord end, which plugs into my sous vide controller, in parallel to the temperature dial on the stove. When using the sous vide, I pull the stove knob right off and put it in my pocket so that the stove's original circuit cannot be energized while the sous vide is working. When the sous vide is unplugged, I have a dead end female receptacle to keep everything safe from the energized new male end while the stove is being used as normal. Sweet.
flavrt (author)  unlucky.break1 year ago
We were thinking along the same lines, but I strongly encourage you to completely isolate the circuits. You'll feel good about it, and everybody can put dinner on the table with 3½ burners.

I understand your method, but it can only work for you. Obviously we can't publish an Instructable that routinely energizes a loose cord, or with even the remotest possibility of shorting out-of-phase circuits.

Be safe, my friend.
roycetaft1 year ago
I really like how efficient this is! Great job!
flavrt (author)  roycetaft1 year ago
Thank you. Efficient use of cooking heat is major concern in a tropical climate. I wouldn't consider running the oven under the stove top shown here for 9 months out of the year.
lomeranger1 year ago
What could go wrong? This is an elegant solution for cooking but man, I don't think this will fly with my wife.
I don't see why this wouldn't work with a single cooking range from your local thrift shop.
flavrt (author)  roycetaft1 year ago
A temperature controller certainly would work with a hot plate, and I considered that alternative. Unfortunately they are notoriously short-lived and failure prone. Reading reviews at Amazon on a variety of these devices disturbed me.
flavrt (author)  lomeranger1 year ago
That is the right question. It frightened me so much, I almost gave up on publishing this. We should all be skeptical of hacking equipment with household voltage. Even using the best practices, we are vulnerable to the criticism that our design is untested. It's impossible for any one person to anticipate everything that can go wrong.

I mitigated the uncertainty as best I could by copying the original design and keeping my work simple and clean. Of course I watched closely for a long trial run without food. I feel better having inspected the original work for loose and frayed wiring. Also there is a safety advantage gained by lowering the voltage and heat output. Now I'm safer with my hacked stove than leaving a cheap heater running on the counter all night.

All that said, do whatever it takes to keep your spouse content. Srly.