Water Baths and Immersion Circulators

[edsel]

Anyone have operating instructions for a Lauda MS?

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I was never able to locate a manual for the MS, but it wasn't too hard to figure out how to operate it. There are specs and manuals for similar (more recent) models on the Lauda web site, so the operating guidelines should be pretty similar for a (roughly) same-size unit.

I just leave the rotary switch set to the continuouly-variable setpoint and "dial in" the temperature I want. I leave the over-temp threshold a few degrees higher than my target so that the unit will switch off if it overheats. (This only happened once, when I let the water level get too low).

[slkinsey]

Okay... Here is the front of my Lauda MS. What I'd like to know is what, exactly, all these switches do and some good ways to set them. I'll start off with the easy ones: 1 is the digital readout and 7 is the power switch.

[edsel]

Okay... Here is the front of my Lauda MS.  What I'd like to know is what, exactly, all these switches do and some good ways to set them.  I'll start off with the easy ones:  1 is the digital readout and 7 is the power switch.

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Yeah, those were the first ones I figured out, too.

Set the Rotary Switch (2) to the full counter-clockwise position (the lower case greek letter). The switch on mine is finicky, so I usually click it back and forth a couple of times to be sure it locks into the continuous setting.

Submerge the unit in water to cover the immersion heater coils. Turn the over-temp trip dial (6) up past 60 or so. I'm assuming you didn't use super-hot water to fill the tank.

Turn on power switch (7). The indicated temp should be something like 20° - maybe higher if you filled your tank with warm water.

Hold in Setpoint mode button (4). Displayed temp should change to something other than what you were seeing. When the button is held in the display reads your setpoint. Otherwise it reads the actual temp.

While holding in button (4), adjust setpoint dial (5) until the readout shows your desired target temp.

Release the button and watch the temperature climb towards your target. At first the heat indicator (3) will stay lit nearly continuously. As the actual water bath temperature aproaches your target, the light will stay on less. Eventually it will be mostly off, only flickering on when the water temperature drops ~ 0.1 ° below your target.

You can adjust the over-heat trip to just a bit higher than your target setpoint. If the actual temperature ever excedes the trip point, you'll hear a "pop" as the safety relay shuts off the heater.

EDIT: Corrected number of Setpoint dial.

Edited September 1, 2005 by edsel (log)

[reuvens]

OOOps too late...

2 is a preset for the temp shown (25 C, 35 C, 37 C, 56 C). The Symbol is to adjust your desired temperature. So set the switch on the symbol and press...

4 (hold it) then you can adjust your desired temp with button 5...

3 shoes you if the thermostat reached the desired temp or if it is still heating...

6??? No idea...on my Lauda it is the button for the fuse

Edited August 31, 2005 by vue_de_cuisine (log)

[slkinsey]

What is 5? (Double duh. That's what you use to set the custom temperature.)

I assume the over-temp dial (6) means that you set a temperature above which the unit will shut down? (Duh. I just re-read above.)

I am thinking that simply stretching plastic wrap over the tank (aka large stock pot) leaving just enough room for the stem of the Lauda should help quite a bit with the evaporation issue.

Thanks!

Edited August 31, 2005 by slkinsey (log)

[edsel]

I use a big stock pot for my "tank", so there isn't much of an issue with evaporation for shorter cooking times. Sometimes I put aluminum foil over the opening, but plastic wrap sounds like a better idea (easier to see what's going on in the bath).

One thing I didn't notice right away about the circulator is that the tube where the water jet exits the impeller housing is positionable. There's a bend in the tube, and if you rotate it you can direct the water flow up or down. Directing the flow slightly downward creates a nice rolling circulation that keeps the water moving throughout the tank.

I usually lay a small plate (tilted) next to the circulator so that the water movement holds it against the heater housing. It keeps the bags of food out of the way of the heater. I've also used a mesh strainer to hold eggs captive while they slow-cook. They just roll around inside the strainer instead of banging around loose. 64.5 ° C for 45 min, as described in the Hesser article.

[MGLloyd]

This thread reminds me of my days back in the chemistry labs, cooking over a bunsen burner..... Large borosilicate glass beakers make wonderful cooking utensils.

I would, however, echo the sage advice above about sterilizing the heck out of any used scientific equipment and flushing the pumps, hoses, etc. thoroughly. I would probably just replace any plastic hoses, fittings, O-rings and the like to minimize the risk of biological or chemical contamination.

[edsel]

I would, however, echo the sage advice above about sterilizing the heck out of any used scientific equipment and flushing the pumps, hoses, etc. thoroughly.  I would probably just replace any plastic hoses, fittings, O-rings and the like to minimize the risk of biological or chemical contamination.

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That's one reason I bought a clamp-on circulator rather than a complete water bath. The circulator was pretty clean when I got it, but I scrubbed it carefully and ran it with several changes of water (on a high heat setting) before using it with food. Even though the food is usually enclosed in bags I still don't want any nasty residue anywhere near it.

The only thing I've cooked without being vacuum-sealed is the slow-cooked eggs, and that was only after I've used the circulator with so many changes of water that I don't think there could be anything left on it from it's previous life.

[pounce]

I posted this in the sous vide recipe thread, but I found using a steam table pan works well for a vessel. I keep the bag positioned in the water with metal clasps from office depot that have a big magnet on them. I clip the bag and stick to to the side or bottom of the pan.

[DaleJ]

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.

[jsolomon]

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!

[pounce]

I was doing some poking around ont he internet today and I found a new site from polyscience specificaly for souse vide.

www.cuisinetechnology.com

They are specifically marketing immersion and bath units for sous vide. Cool.

They also have one of those "anti griddles" where you can make frozen items on a griddle.

A quote form the site:

Join cutting-edge chefs Grant Achatz (Alinea), Wylie Dufresne (wd~50), Charlie Trotter, and the others who depend on PolyScience Culinary Technology equipment to set new standards in innovation and quality.

Edited September 21, 2005 by pounce (log)

[pedrissimo]

So, I am a home cook getting ready to explore sous vide, and I am grateful for all the information in this thread! I have a question going back to the first post- why not a crock pot- at least as I am learning? I have been mulling for weeks what I could use instead of a recirculating bath until I know I want to invest. Crock pots did not seem so good because of the temperature controls- until I thought of my solution to another slow-cooking project.

I have made a small electric smoker using a hot plate, but I pulled the thermostat from it (big temperature fluctuations). I installed a dimmer switch in an extension cord (so the wattage isn't right...), and I can precisely control the current getting to the hot plate. Why not use this to control the crock pot? At my lab, we have the cheap kind of water baths, always with a thermometer attached, and an analog dial- we control temperature by trial and error, but then it holds nicely.

Now the other issue about a crock pot is that it is not recirculating. How big of an issue is this, really? If it is full of water, and has the additional thermal mass of the crockery, it ought to hold temperature nicely. Granted, the temperature could be different at the top and the bottom, but shouldn't convection take care of this? At least for relatively short cooking times? (I wouldn't do ribs for 36 hours...)

[nathanm]

A crock pot will work to some degree. You won't have control over temperature however - it will be at whatever temp the crock pot is set at from the factory which is probably 150F to 170F. Also, they are not very accurate - instead of staying at a constant temp it will fluctuate. If you already have one, give it a try, but realize the limitations.

[Shalmanese]

I've been thinking a bit about sous vide of late and I think that using water baths may not be the best approach. Instead of relying on a feedback loop to maintain a steady temperature of water, why not use a different chemical that has the desired chemical properties you are after, namely, boiling point.

Ethanol at 78.4C is probably too high to be useful. But Methanol happens to have a boiling point of 64.7C which is conveniently close to medium rare for meats. Propanal is at 49C which is just a tad too high for most fish but still workable. I'm sure other chemicals could be mixed to produce any desired range of temperatures.

The key here is that if you do this, then the hardware can be made very very cheaply. You dont need computer controls, thermostats or variable heat. You just need a heating element to keep the liquid at a boil and a condensor to form a closed loop. The only real issue I can see here is worries about the permiability of the cooking liquid through the plastic pouches.

If you only wanted a sous vide machine to do meats to medium rare, then you could just use methanol and have an almost perpetual sous vide machine for peanuts. If you wanted variable temperature control, then ideally, you should use a liquid that is cheap, non-toxic, has a boiling point of around 30C or so and can scale from 30C to 100C depending on the proportion you mix with water or another fluid.

Whether such a chemical exists, I don't know. Someone with a bit more chemical knowledge would have to weight in. But I would love to know if the methanol rig has a chance at practicality.

edit: It occurs to me that if you want an added layer of protection, you could double bag your food. Fill the inner bag with food and then place it in the outer bag and fill it with hot water. That way, only the water is in contact with your food but you get the accurate temp control as well.

Edited May 31, 2006 by Shalmanese (log)

[Silly Disciple]

I fail to see what the advantage would be over a water bath. Inmersion circulators are not that expensive, and probably bound to decrease price as the technique spreads. You can already buy them second hand for a couple hundred dollars. If you think about electricity consumption, then I'm not sure the closed loop is more expensive than having a continuously going heating element. And water for sure seems safer for food than chemicals, no?

[pedrissimo]

Nathan,

I was thinking to get around the temp control issue by either setting the pot on high- if it doesn't cycle, or cutting the temp control out of the circuit in the pot. Then I plug it into my modified extension cord:

one power strip + one plastic light switch box from the hardware store + one dimmer switch from the same store. Ten minutes of cutting wires and screwing them together = infinite adjustment of the temperature. Total cost, including crock pot from Goodwill- $11. (I have many old powerstrips, which I use because they are free and have high gauge wire)

My only question is what the temp would be like at different heights in the bath- I am hoping that the combination of the crock pot itself distributing heat, + natural convection of heating water ought to make things close enough to equal.

Thoughts?

A crock pot will work to some degree.  You won't have control over temperature however - it will be at whatever temp the crock pot is set at from the factory which is probably 150F to 170F.    Also, they are not very accurate - instead of staying at a constant temp it will fluctuate.  If you already have one, give it a try, but realize the limitations.

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Edited May 31, 2006 by pedrissimo (log)

[nathanm]

Responding to several posts here.

Using a volitile material like ethanol or methanol is a very bad idea, because the fumes are flammable. So don't do this!

Even if you found a low boiling point fluid, you would have to contend with the fumes caused by the evaporation. In many cases (including both ethanol and methanol) the fumes are toxic! You postulate a condensor loop to keep it a closed system but this is prone to leaks and could be dangerous. Plus, as you point out, most organic solvents will dissolve the plastic bag.

There is no practical way to make a sous vide cooker with low boiling point fluids.

You can find fluids that have a HIGHER boiling point than water - for example vegetable oil. In fact, a deep fat fryer is, in effect a "water" bath that uses oil instead of water. They generally have very poor temp control. Plus, you virtually never want to do sous vide above 212F because the bag will pop.

Lab water baths use a PID temperature controller, which is a very accurate kind of thermostat that can do precise control. Crock pots have very simple, crude and not very precise on-off temp controllers that have a much wider range of variation. They have two problems - first they are not well calibrated - so it might be 160F or it might be 170F, no two crock pots even of the same make are likely to be calibrated exactly the same. The other problem is that there is a wide range of temperature variation in an on-off controller. So, a controller nominally set for 160F will usually go through a zig-zag, ranging from 155F to 165F, or even wider swings. Plus or minus 5 degrees is not uncommon - plus or minus 10 degrees is possible.

This is considered good enough for slow cooking, but it is not good enough for many kinds of sous vide - particularly at the lower temperature ranges.

If you want to do sous vide at the high temperature found in most crock pots, then you may be able to use it without modification. But you'll be locked into whatever temperature variation it has. Use a digital thermometer that records min / max to check this.

Using a dimmer with a crock pot will not work.

The dimmer will make the heating coil operate at lower temperature, but the thermostat will still be set at the factory set temperature! If the dimmer is very low then it won't reach that temp, but you will not have a theromostatic controlled result. So this idea is not going to work.

But perhaps I misunderstood your post. Another way to do this is to take the high/low temperature setting of the crock pot, and then splicing in a potentiometer (dimmer) so that you can vary the temperature at which this works. This might work, but if you are that good an electronics hacker you don't need me to tell you about it . The main problem here is that it will still de a very crude on-off controller, and will likely have the same zig-zag temperature variations. It might work well enough, or it might not. Hard to say.

One thread on eGullet (don't have it handy) covers somebody's homemade water bath plans, including some sort of temperature controller. I haven't built it, but you could look at that.

One could imagine installing a PID or similar controller in a crock pot, but unless you are a skilled gadget hacker with a surplus PID lying around this is going to be more costly / time consuming than getting a surplus water bath on eBay. If you look on espresso websites there are discussions of adding PID control to an espresso machine, but I can't imagine how this could be worth it cost wise.

I have seen a gizmo which is a PID or similar controller, with a plug socket, so you could plug in any heating coil and control it to reach a temp. However, again, I think that cost and so forth.

[pedrissimo]

Nathan,

I am no electronics expert, just a science teacher. I am familiar with the temperature controller in the crock pot- it is a crude switch including one piece of metal that bends with heat, breaking the circuit. I would just cut that out, and wire the circuit back together with a wire nut.

The dimmer switch (yes, I think potentiometer) is my answer to a PID (I have the Rancilio Silvia, beloved object of the espresso electronics hackers, and it makes great espresso without mods- just use actually fresh roasted coffee!)

The dimmer, as far as I understand it, is a coiled resistor. You move the knob, and you change the amount of resistance in a circuit. The more resistance to current, the less current gets through to the appliance.

I have actually put the dimmer in an extension cord, so I can try it on my other crazy project, electric smoking in a flowerpot (a la Alton Brown, who really is a science teacher!). It works great on that. Tell you what- I will fix up the crock pot, and post how it works for the home cook.

My only issue still is, supposing my crazy wiring experiments work, what will happen to the temps in the water! How on Earth can I measure temperatures at different heights? I sure don't want the top of the salmon cooking faster than the bottom- or vice versa.

Cheers,

Peter

Lab water baths use a PID temperature controller, which is a very accurate kind of thermostat that can do precise control.  Crock pots have very simple, crude and not very precise on-off temp controllers that have a much wider range of variation.  They have two problems - first they are not well calibrated - so it might be 160F or it might be 170F, no two crock pots even of the same make are likely to be calibrated exactly the same.  The other problem is that there is a wide range of temperature variation in an on-off controller.  So, a controller nominally set for 160F will usually go through a zig-zag, ranging from 155F to 165F, or even wider swings.  Plus or minus 5 degrees is not uncommon - plus or minus 10 degrees is possible.

This is considered good enough for slow cooking, but it is not good enough for many kinds of sous vide - particularly at the lower temperature ranges.

If you want to do sous vide at the high temperature found in most crock pots, then you may be able to use it without modification.  But you'll be locked into whatever temperature variation it has.  Use a digital thermometer that records min / max to check this.

Using a dimmer with a crock pot will not work.

The dimmer will make the heating coil operate at lower temperature, but the thermostat will still be set at the factory set temperature!    If the dimmer is very low then it won't reach that temp, but you will not have a theromostatic controlled result.  So this idea is not going to work.

But perhaps I misunderstood your post.  Another way to do this is to take the high/low temperature setting of the crock pot, and then splicing in a potentiometer (dimmer) so that you can vary the temperature at which this works.  This might work, but if you are that good an electronics hacker you don't need me to tell you about it .  The main problem here is that it will still de a very crude on-off controller, and will likely have the same zig-zag temperature variations.  It might work  well enough, or it might not.  Hard to say.

One thread on eGullet (don't have it handy) covers somebody's homemade water bath plans, including some sort of temperature controller.  I haven't built it, but you could look at that.

One could imagine installing a PID or similar controller in a crock pot, but unless you are a skilled gadget hacker with a surplus PID lying around this is going to be more costly / time consuming than getting a surplus water bath on eBay.    If you look on espresso websites there are discussions of adding PID control to an espresso machine, but I can't imagine how this could be worth it cost wise.

I have seen a gizmo which is a PID or similar controller, with a plug socket, so you could plug in any heating coil and control it to reach a temp.  However, again, I think that cost and so forth.

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[scott123]

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.

Edited June 1, 2006 by scott123 (log)

[Shalmanese]

Responding to several posts here.

Using a volitile material like ethanol or methanol is a very bad idea, because the fumes are flammable.  So don't do this!

Even if you found a low boiling point fluid, you would have to contend with the fumes caused by the evaporation.  In many cases (including both ethanol and methanol) the fumes are toxic!    You postulate a condensor loop to keep it a closed system but this is prone to leaks and could be dangerous.  Plus, as you point out, most organic solvents will dissolve the plastic bag.

There is no practical way to make a sous vide cooker with low boiling point fluids.

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OK, so maybe not methanol. But are you sure there isn't a single chemical that would be appropriate? If you double bag it, you can make the outside container anything you want. You could even use a metal box with an airtight seal.

In fact, an alternative might be to use some sort of inverse heatpipe system. Instead of sealing up the food, you just seal up the methanol and use it as a heating element which can only ever get up to 64.7C. Immerse it in a well enough insulated water bath and you have worry free sous vide. This would move away from being home built to being an industrial product but I still it has promise.

[nathanm]

A hermetically sealed heat pipe system would certainly work

[Silly Disciple]

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

[nathanm]

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

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I agree....one might imagine that you could use some techinque like this to make a cheaper water bath for home use. However, the most likely way this will happen is a manufacturer will simply make a cost-reduced version of a standard lab water bath, with some corners cut. The home appliance market has very different volume and profit margin than lab equipment.

[edsel]

Over on the recipes topic I posted a link to a Ruhlman podcast interview where he mentions that Thomas Keller was planning to introduce some low-cost equipment for sous vide cooking at home. His new book uses lots of sous vide technique, and he wanted to provide a way for home cooks to play along.

I think the book publication has been delayed, so who knows if this will ever materialize

My water bath goes up to 11. ←