DIY Sous Vide Temperature controller

[bennelson]

http://www.youtube.com/watch?v=t_FsO_4gplY#t=21

Recently, I started playing around with "Sous-Vide".

For those of you who don't know, this is a cooking technique where food is sealed in a vacuum bag and then cooked in hot water AT THE TEMPERATURE YOU WANT TO FINISH IT AT. That means it's pretty much impossible to overcook your food, and it's great for hold times, one reason that restaurants have been using it for years.

But perhaps even more importantly, it's nerdy as hell.

By building my own "Sous-Vide Controller", I can turn my Crock-Pot into a PRECISION TEMERATURE CONTROLLED DEVICE.
That means good-bye to HI/LO and hello to exactly 137 degrees.

There's already lots of good info on building your own from essentially off-the-shelf parts (Here's one of the better ones) so I won't bore you with the details. Essentially, I'm using an all-purpose temperature controller ordered from Amazon.com to turn an electric outlet on and off. I used a project box I had kicking around, so that's why it has too many holes in it and there's that gap in the front, I'm using what I had instead of spending another ten bucks to buy a box.

The setup is pretty much like a home furnace thermostat. Below a certain temperature, the controller turns the outlet on (creating heat, by turning your Crock-Pot or other heating device on) and above that temperature, turns it off (which allows the water to cool, trying to get back down to room temperature.) In this way, the temperature is always held very closely around your set temperature. This works really great for steaks! (Just sear them in a pan when all done for show!)

You might be thinking by now that this sounds like a very nerdy/overly-complicated way of cooking a steak. It's actually pretty simple, and you get super-tender food, but if you aren't a steak/venison/bison person, how does a DIY YOGURT-MAKER sound? Making yogurt requires a fairly specific temperature range. Why not drop a few mason jars into a Crock-pot, fill with your pasturized and cultured milk, and set the controller overnight for 107 degrees?

Into exotic beer-making and other kitchen science? A lot of that can use temperature control as well!

Besides kitchen uses, the controller can turn on and off any other AC appliance based on temperature. For example, you could have a light-bulb heat your chicken coop in the winter, and have it turn on and off as needed. This both keeps your birds warm and saves energy when not needed.

The only down-side I can think of is that "Sous-Vide" typically relies on the food being vacuum-sealed in plastic. Since I'm trying to get away from plastic in general, I'd like to figure out what the other options are. Mason jars are one possibility, but would require that they are completely full to conduct heat from the water bath. Canned beef stew for dinner anyone?

Anyways, I'll keep you updated as my kitchen experiments continue.

-Ben

PS: Commerical Sous-Vide appliances run $250-to $500. That's pretty pricey for a fancy Crock-Pot. I built this controller box for about $30.

[AC_Hacker]

Originally Posted by bennelson

...Recently, I started playing around with "Sous-Vide"...

Nicely executed project.

I tried the same thing a while back. I didn't get any further than cooking an egg. I was intrigued by the "6X degree C egg" concept, and the effects of precision temperature control on the various egg proteins.

From your explanation, I couldn't tell if you are using an on-off temperature controller with adjustable on-points and off-points, or if you went all in for a PID controller?

The PID controller seems to be "the bomb" where Sous-Vide cooking is concerned, because PID can hold much tighter temperature levels (.1 degree C) and don't feature those nasty temperature swings that an off-on controller would have.

Also, it seems that in the geek-cooking world, Sous-Vide cookers don't rely on natural convection of the water, but instead they feature some kind of mechanical water-circulation feature to guarantee uniform temperature dispersion.

But back to the egg... it was delicious, and it was as creamy and subtle as I had expected. If I were to continue, I would make sure that I used only the freshest organic eggs possible.

But I am moving away from eating animal protein of any kind, more for health reasons than for reasons pertaining to 'humane treatment of animals' reasons.

I'm not aware that Sous-Vide techniques apply to vegetarian cooking.

So, I have set my PID controller aside for some future project.

Have you heard of Modernist Cuisine: The Art and Science of Cooking? It seems to be the Super Highway that leads in the same direction in which you are going.

Good luck with your explorations!

Best,

-AC

[bennelson]

The temperature controller is ON/OFF only.

You can program it for either a heating or a cooling mode. That is, it completes a circuit anytime the temperature is above or below your set-point, depending on how you program it. It's very simple, and it accurate to 1 degree (f).

I wasn't using any kind of water circulator, and it all worked fine. If I did want to use a water circulator, I wonder how a "power-head" from a tropical fish aquarium would work?

I made a batch of yogurt using this setup, and it turned out great. I put the milk and yogurt starter in mason jars and put those in the water. it turned out much better than the same yogurt made in the oven with the "hot-box" technique.

[SDMCF]

This is interesting to me because I am working on a temperature controller with design goals that are very different but maybe the hardware could be similar. You want a constant temperature and I want to control or even promote temperature fluctuations.

Initially I am controlling my freezer temperature. Our electric tariff is linked to the wholesale electricity price. This varies hour by hour, with the prices for each hour of each day published on the web around midday the previous day. My controller will grab these prices from that web page and then control the device(s) to minimise costs. So the freezer will run to a lower temperature when electricity is relatively cheap, and allow the freezer to warm up (but still keep it "cold enough") when prices are high. Eventually I hope to apply this approach to control other things, not necessarily temperature-related. Mainly for geek-appeal rather than in anticipation of huge cost savings.

I am creating my own controller based on an Arduino because I couldn't find anything off-the-shelf that I could easily modify for this purpose. When you were searching for a controller did you find any with an internet connection? Or any way of externally (programatically) setting the required temperature?

[AC_Hacker]

Originally Posted by SDMCF

This is interesting to me because I am working on a temperature controller with design goals that are very different but maybe the hardware could be similar. You want a constant temperature and I want to control or even promote temperature fluctuations.

Initially I am controlling my freezer temperature. Our electric tariff is linked to the wholesale electricity price. This varies hour by hour, with the prices for each hour of each day published on the web around midday the previous day. My controller will grab these prices from that web page and then control the device(s) to minimise costs. So the freezer will run to a lower temperature when electricity is relatively cheap, and allow the freezer to warm up (but still keep it "cold enough") when prices are high. Eventually I hope to apply this approach to control other things, not necessarily temperature-related. Mainly for geek-appeal rather than in anticipation of huge cost savings.

I am creating my own controller based on an Arduino because I couldn't find anything off-the-shelf that I could easily modify for this purpose. When you were searching for a controller did you find any with an internet connection? Or any way of externally (programatically) setting the required temperature?

This is a really fiendishly clever and geeky project. I envy Finland for having daily energy information available for purposes such as you are engaging in. And I admire you for wanting to tackle a DIY project that will optimize energy use by using that information.

Regarding Ethernet connectivity, there are Ethernet shields available for Arduino boards.

In fact, HERE_ARE_SOME for about $10 US.

This looks to be an awesome project, please start a new thread for this and keep us informed of your work (lots of photos, code, etc.).

Depending on how deep or long you want your cycles to go, you might want to consider Phase Change Material (PCM) to chemically store and release energy, at a temperature below your sub-freezing set point.

I have discovered that large pharmacies receive shipments of vaccines in high-quality foam containers and they use PCM material for the duration of the shipping. I have asked for some of the PCM, and they have happily given it away for free... of course, I did flirt with the beautiful girl at the pharmacy counter, which never hurts when you are looking for free Phase Change Material.

Also, it is quite apparent to me that you, SDMCF, are a totally driven energy geek. There is no known cure for this condition, except even geekier projects.

Therefore, you may have SEEN_THE_PROJECT that used Vacuum Insulated Panels (VIP) to build a high efficiency, low energy loss door... If you wanted to ascend to even higher levels of geekhood, you might consider ripping out the outmoded insulation from inside your existing freezer, and replacing it with vacuum panel insulation.

Combining VIP insulated freezer with PCM and a DIY web-based Smart Energy Controller would assure you, SDMCF, a permanent place of admiration in UberGeekWorld.

Good Luck!!

-AC

[SDMCF]

AC, Thanks for your kind words. I will create a new thread about this, but just for now here are some quick answers.

I am using an Arduino Ethernet Shield to get internet access, and it seems to work well.

I wasn't aware of phase change materials being used for vaccines, but it makes sense. I will have to ask at my local pharmacy to see if I can get some. Do you know what materials they use and at what temperature they change state?

I had seen the project about Vacuum Insulated Panels. Maybe I will look into that idea later, after I have the controller working.

[AC_Hacker]

Originally Posted by SDMCF

...I wasn't aware of phase change materials being used for vaccines, but it makes sense. I will have to ask at my local pharmacy to see if I can get some. Do you know what materials they use and at what temperature they change state?...

I don't know what the material is, regarding the phase change temperature, I think I can find out experimentally pretty easily.

Give me a few days to get set up.

I did use the box and some frozen PCM blocks to keep food cold during a ccamping trip, and it did a great job.

-AC

[where2]

Originally Posted by AC_Hacker

I don't know what the material is, regarding the phase change temperature, I think I can find out experimentally pretty easily.

I've inquired with my friend the pharmacist to determine if she knows what's in the PCM pack. Considering I went through multiple college chemistry courses with her, and she made better grades than I did, I know she knows a thing or two about chemistry. If she can't figure it out, maybe I can convince her to ship a pack to our fellow friend and classmate who is now a high school chemistry teacher for analysis.

I've seen multiple types of medications shipped using insulated packing boxes. I wonder how many types of these PCM packs there are?

[NiHaoMike]

In that context, I wonder if "phase change material" is just a fancy term for an icepack with some additives.

[AC_Hacker]

Originally Posted by NiHaoMike

In that context, I wonder if "phase change material" is just a fancy term for an icepack with some additives.

You need to do some research...

-AC