Water Baths and Immersion Circulators

[pedrissimo]

Scott,

I had thought of having two probes. My probe is about 6" long, and being metal, conducts heat well. I am ok in the oven with this, because when you stick it in a hunk of meat with some left in the air, the average temp will come mostly from the meat, as air is not good at conducting heat. Surely, the tip isn't the only part that measures temperatures in water? Perhaps those tiny grill thermometers for steak, chicken etc..., sealed in plastic, and ... The aquarium pump sounds like something I might use if I was looking into long cooking times. They also make electric pot stirrers for the lazy cook.

On the switch- here is what I know about such things: the heater in a crock pot online is rated at 300W, while the dimmer switch is rated for 600W. The heater is just a big resistor, and shouldn't be damaged by the dimmer- it is a piece of ceramic/metal that conducts some electricity but also resists the flow of current- this is why it heats up. The modern dimmer switches are not variable resistors like I said in an earlier post- they actually cut off the flow of electric current intermittently, many times a second, and the dimmer you want it, the longer they turn off the current. I tried mine yesterday with my hot platee plugged in, (probably not wise, as the hot plate would like 100W), and I was finally able to get good control on my electric home meade smoker. I will buy a crockpot at Goodwill and try it, though with one probe for now, and let you know how steady I can get the temperature.

The dimmer switch itself ought to be almost infinitely variable, not big graduations like a crock pot switch. You can certainly set it to 11, but why not get just that little bit more, and set it to 12? But don't look at it, Don't even think about it!

Cheers,

Peter

How on Earth can I measure temperatures at different heights?

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You can position the tips of two digital probe thermometers at different locations in the liquid. They're 20 bucks a piece, but you'll still be well below the couple of hundred dollar outlay mentioned previously. You can set them to trigger alarms- one a degree above your target setting, one a degree below.

If you can get a crockpot to do even close to relatively precise sous vide, I would be very very impressed. I've been considering sous vide confit as well as sous vide hollandaise and maybe pudding, but I definitely don't have a couple hundred bucks to spare. If you can pull off an affordable alternative, I am so there!

Oh, how about an aquarium water pump for circulating the water? I think those are in the 15 dollar range.

Is a dimmer safe with a heating element?

If you are eventually able to get this to work, are there dimmers that can be bought or made that could be broken down/marked with very tiny increments? For some reason I'm picturing one of the nobs from a sound board, except maybe even a longer distance for greater precision.

My water bath goes up to 11.

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[Shalmanese]

What would the point of such a system be? A regular inmersion circulator seems cheaper, safer and more flexible.

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I guess the engineer in me is just irked by the sheer primitiveness of the system. It just seems to me like there should be a better way to do this. The thermal charecteristics of water make it very hard to achieve good performance with and theres just too much that can go wrong. OTOH, even though a methanol heatpipe would be more complicated to manufacture, it would be almost foolproof to use and be both faster and more accurate to boot.

[scott123]

Hmmmm... how about carefully drilling two holes in the side of the crockpot, one near the bottom and one near the top of the waterline and inserting thermometers through those, anchored with silicone caulk?

This would be for continuous monitoring, of course. You might be able to just get away with taking the temps of the top and bottom water with an instant read thermometer at different time intervals. This will tell you if there is any discrepancy. My guess is that there won't be.

Here's my next question. Why don't they incorporate dimmers in home ovens? The on/off cycle on my oven gives me temperatures within a 50 degree range of the temperature I choose. It's ridiculous.

[pedrissimo]

Soo, I got the crock pot. I took it apart, and then put it back together- the switch in this old one is not a cycling one- it just incorporates more or less of the wires wrapped around the crock. But what is very cool is that the heat comes from a very long thin wire wrapped around the crock's sides- most of the way from the bottom to the top- so the heating should be even.

Now, I have noticed that when I stir the water, the temperature fluctuates- about 2-3 degrees. However, the temperature is nice and stable overall.

http://forums.egullet.org/uploads/11491352..._3006_85429.jpg

So the crock pot is unaltered. (they may not all have such a simple switch, but most probably do...)

The dimmer is from home depot- $4.99

The blue box is also from home depot- $1

The wiring is not complex, and the dimmer can certainly handle the wattage.

As I said, the temperature is amazingly stable (once it is set, it stays within a degree for minutes at a time)- the only issue is that it changes so slowly that it is hard to dial it in very quickly- Scott, your suggestion of marking the dial would make good sense. I added hot water and then some cold later to try moving the temperature.

I saw on another thread about sous vide a suggestion for a heater/stirrer, which would be useful for keeping water moving past the food on the way up to temp- I guess I will stir in my early experiments! Overall, this home made sous vide water bath, while not perfect, will be much better than a pot on the stove. I would definitely get the biggest size possible- I have seen up to six qts. My little one is kind of small (looks like 4 qts)- but at least it has one heck of a thermal mass!

To make life easier later, a PID and stirrer would be cool- if i could get a PID and temperature probe that I could just plug this into, then I could use it on my electric smoker and my fridge that has become a sausage curing cellar when I am not doing this.

BTW Scott- I would skip the drilling, and just try to figure out how to keep the water moving.

Peter

Hmmmm... how about carefully drilling two holes in the side of the crockpot, one near the bottom and one near the top of the waterline and inserting thermometers through those, anchored with silicone caulk?

This would be for continuous monitoring, of course.  You might be able to just get away with taking the temps of the top and bottom water with an instant read thermometer at different time intervals. This will tell you if there is any discrepancy. My guess is that there won't be.

Here's my next question. Why don't they incorporate dimmers in home ovens? The on/off cycle on my oven gives me temperatures within a 50 degree range of the temperature I choose. It's ridiculous.

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[Shalmanese]

Soo, I got the crock pot. I took it apart, and then put it back together- the switch in this old one is not a cycling one- it just incorporates more or less of the wires wrapped around the crock. But what is very cool is that the heat comes from a very long thin wire wrapped around the crock's sides- most of the way from the bottom to the top- so the heating should be even.

Now, I have noticed that when I stir the water, the temperature fluctuates- about 2-3 degrees. However, the temperature is nice and stable overall.

http://forums.egullet.org/uploads/11491352..._3006_85429.jpg

So the crock pot is unaltered. (they may not all have such a simple switch, but most probably do...)

The dimmer is from home depot- $4.99

The blue box is also from home depot- $1

The wiring is not complex, and the dimmer can certainly handle the wattage.

As I said, the temperature is amazingly stable (once it is set, it stays within a degree for minutes at a time)- the only issue is that it changes so slowly that it is hard to dial it in very quickly- Scott, your suggestion of marking the dial would make good sense. I added hot water and then some cold later to try moving the temperature.

I saw on another thread about sous vide a suggestion for a heater/stirrer, which would be useful for keeping water moving past the food on the way up to temp- I guess I will stir in my early experiments! Overall, this home made sous vide water bath, while not perfect, will be much better than a pot on the stove. I would definitely get the biggest size possible- I have seen up to six qts. My little one is kind of small (looks like 4 qts)- but at least it has one heck of a thermal mass!

To make life easier later, a PID and stirrer would be cool- if i could get a PID and temperature probe that I could just plug this into, then I could use it on my electric smoker and my fridge that has become a sausage curing cellar when I am not doing this.

Peter

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Hrmm... that thermometer your using has an temperature alarm on it right? Instead of going for fullblown PID, try just having a state machine approach. Hook into the signal circuit for the alarm, If the alarm is not ringing, then you should be in the "heating" state and pumping in lots of power into the crockpot. If the alarm is ringing, you should be in the "maintenence" state and keeps the temperature stable. A simple switch and a bit more wiring and you should get that working. Kudos for being the first one to try. Set the alarm to say, 5F below your target temperature and see what happens.

The stirrer idea was mainly to alleviate hotspots caused by a concentrated heat source. With the winding design of the crockpot, I wonder if it's really neccesary. I wager that maybe the very top inch of the water might be significantly cooler than the rest but theres very little actual variation within the main body of water. As long as your sous vide bags are heavier than water (tape some weights to the bag), then I highly doubt the temp variations are going to warrant a stirrer.

Edited June 3, 2006 by Shalmanese (log)

[pedrissimo]

Sooo,

This work 'hook' you use. I suppose it only seems magical because I have no idea where the signal circuit for the alarm is, nor what it looks like, nor what would be involved in 'hooking' just exactly what into it?

I am willing to try, but please, sir, I only teach ninth grade science! I get series circuits, parallel circuits, resistance (this is what light bulbs and heating elements do), and how to connect thick wires with wire nuts and MAYBE how to use a soldering iron.

So:

What thing do us simple folk hook into this signal circuit?

How do we find said circuit?

I assume we solder to actually do the 'hooking'.

Cheers! And thanks!

Peter

[Shalmanese]

Oh right, I assumed that if you were considering building a PID, you had a bit more electronics knowledge. in order for the alarm to beep, obviously some electricity has to be going into it right? So what you do is you find the speaker or whatever is producing the sound, and then you find the wires leading to that. If you had a multimeter, I guess you should find out what voltage and current it's sending out. Actually, thinking further, it's probably sending a pulsed signal to the speaker which may or may not be a problem. Does the alarm shut itself off after a few minutes of beeping? If so, then it wont be usable.

Anyway, regardless of the voltage you can buy a simple electric component with 4 connections that basically says IF the voltage on C0 is LOW, then connect C1 with C3, IF the voltage on C0 is HIGH, then connect C2 with C3.

So what you do is you patch the alarm signal into C0, then connect the mains power directly to C1, connect the dimmer switch modulated mains power to C2 and connect C3 to the crockpot. If the alarm is not beeping, it acts like a normal crockpot, if the alarm is beeping, it goes through the dimmer switch.

Unfortunately, I learnt all my electronics via osmosis and not by actual experience so I don't know what the thing is precisely called or how to find one but I'm sure someone else can chime in.

[FoodZealot]

This will display my ignorance.  I have just purchased, through eBay, an imersion heater circulator from a lab in New Jersey.  I intend to clean it as well as I can.  But if all cooking is done sous vide do I need to be super duper careful with the cleaning?  Thanks.

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YES!

Ask your cleaning supplier if they can get you some phosphoric acid disinfectant Citrinox is one brand that comes directly to mind. You want to clean this as well as you can. Then do it again.

Good luck!

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I've been trying to find the cleaner mentioned, Citrinox, and have not have any luck. Any suggestions on where a consumer might be able to find it? Thanks.

~Tad

[nathanm]

I've been trying to find the cleaner mentioned, Citrinox, and have not have any luck.  Any suggestions on where a consumer might be able to find it?  Thanks.

~Tad

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Cole Palmer has it.

[BryanZ]

I'm looking at picking up a smaller second bath to keep at a different temperature than my main one. The one I'm looking at is 10x6x3(deep). This would be more for individual servings of steaks, fish fillets, eggs, etc.

Is this too small, especially with a depth of only 3"? Does anyone have any experience with American Dade Tek-Pro?

I'd love to hear insights.

[Dave Weinstein]

Has there been any movement towards consumer-grade baths? I'm uncomfortable using recycled lab equipment when I don't know what it was doing before, and I'm unwilling to spend the amounts required for a new circulator.

[jsolomon]

You can always order a new insert from the manufacturer.

Of course, if you have a recirc type, that doesn't do nearly as much good.

[pedrissimo]

Has there been any movement towards consumer-grade baths? I'm uncomfortable using recycled lab equipment when I don't know what it was doing before, and I'm unwilling to spend the amounts required for a new circulator.

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Dave,

I have been playing with this for a week, and I think I have found a relatively easy solution for regular people. My crock pot is holding temps perfectly, within a degree, for hours. Don't get the ones with digital controls, because I plug the thing into an extension cord that i have wired a dimmer into. The dimmer wiring is easy (really!) and safe. The next step is an aquarium air pump- they are $10 for a 5gallon tank. The beauty of an air pump is that you don't suck hot water into the pump- it is one way, and you get plenty of water movement. You need a wired probe thermometer- i got my no-name one for $15 at the local grocery. With the $30 for the crock pot (I would get the oval shaped one!), you are looking at ~$60 plus vacuum sealer.

I have yet to experiment with the air pump- but it ought to do the trick. I keep this setup on a shelf in my utility room off the kitchen- as all the prep happens in the kitchen and all that i do with the cooking is drop stuff in and set the timer. By the way, the addition of even frozen sous vide packets doesn't change the temperature much, and it goes back to temp quickly.

It isn't hard, and it works- certainly as well as any consumer level product i have ever owned!

Peter

[jsolomon]

I wouldn't expect a $15 digital thermometer to give you good results. If you want good control, get a quality liquid in glass thermometer for roughly the same amount. They don't get subjected to the vagaries of battery life like a digital thermometer does, so they tend to give more reproducible results.

[jmolinari]

You cna actually get a $50 temperature controller, wire in a thermocouple, and it acts as an on/off switch for the crock pot.

Buy one of these:

http://www.dwyer-inst.com/htdocs/temperatu...iesTCSPrice.cfm

and all you need is a thermocouple probe, and you should be accurate to 1% of the temperature.

jason

[jsolomon]

That's not exactly true, jmolinari. Thermocouples, in order to be accurate to within 1% need to be calibrated. There are several methods of doing this, but boiling liquid is not the best, unless you want to do some neat math with the altitude and barometric pressure.

[Dave Weinstein]

That's not exactly true, jmolinari.  Thermocouples, in order to be accurate to within 1% need to be calibrated.  There are several methods of doing this, but boiling liquid is not the best, unless you want to do some neat math with the altitude and barometric pressure.

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Well, I live at ~50 ft above sea level...

[scott123]

I have been playing with this for a week, and I think I have found a relatively easy solution for regular people. My crock pot is holding temps perfectly, within a degree, for hours.

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I'd be curious to hear which temps you been using it at? Is it as stable at, say, 100f as say, 200f?

Although you'd never use 200f for sous vide, I'm still curious if it's stable over a wide range of temperatures.

[pedrissimo]

I have been playing with this for a week, and I think I have found a relatively easy solution for regular people. My crock pot is holding temps perfectly, within a degree, for hours.

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I'd be curious to hear which temps you been using it at? Is it as stable at, say, 100f as say, 200f?

Although you'd never use 200f for sous vide, I'm still curious if it's stable over a wide range of temperatures.

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So far, but I haven't had time to develop lots and lots of experience. However, since there is no cycling thermostat, and because the current going into it is steady, I don't see an obvious reason for unsteadiness- perhaps at 200 you would be adding more water to replace evaporation than at other temps. I have some pork belly at 180 that has been like that all day...

[FoodZealot]

Cole Palmer has it.

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Thanks, Nathan. From there I found that I had been spelling it wrong. Citranox is the correct spelling, and there are a number of sources, ranging from about $30 a gallon and up.

~Tad

[nathanm]

You cna actually get a $50 temperature controller, wire in a thermocouple, and it acts as an on/off switch for the crock pot.

Buy one of these:

http://www.dwyer-inst.com/htdocs/temperatu...iesTCSPrice.cfm

and all you need is a thermocouple probe, and you should be accurate to 1% of the temperature.

jason

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This looks like a good example of an on-off or "bang-bang" controller, which turns the item on or off depending on the temperature. This will be OK for many sous vide applications, but it isn't anywhere near as accurate as a PID controller which is more expensive.

The advantage is that it is cheap, and easy to use because you just plug it in.

If you wanted to do PID control, here is a site that has do-it-yourself instructions on adding a PID controller to an espresso machine. The process would be very similar for a crock pot, or improvised water bath. http://www.murphyslawonline.com/silvia/

[JacobCooks]

Hey everyone, I'm bidding on an immersion circulator on ebay right now (lauda), but the seller said that it does not come with the clamp.

Has anyone ever been in the same situation? Can you buy just the clamps online? Anybody ever make the clamp themselves?

Any feedback would be cool, thanks.

P.S. I can't wait to start doing some sous-vide. Just looking at all the threads makes me ache.

[BRM]

I got mine (a Haake) on eBay as well and it came without clamps. Even without the clamps it rests very securely on the rim of one of my stockpots with is what I use for most of my SV. So my advice would be to get it home and see if you really need them.

[hambone]

so your the guy who outbid me huh? well congrats on the win.

[JacobCooks]

so your the guy who outbid me huh? well congrats on the win.

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Actually, I got outbid now.

There's a few going right now, as well as a few water baths, so I'll have to check those out too.

I'm not going to start the new year without getting my hands on one of these!