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DIY Compact Sous Vide Circulator

This is a description of how I built my own Sous Vide circulator.

My goal was to build an accurate, low cost and compact sous vide circulator that could fit into an adapted plastic box or be self standing in any regular pot.
After some research on how professional products are designed I ended up having the following sous vide circulators as inspiration:

PolyScience 7306C Sous Vide Thermal Circulator with Protective Cage - 1128$

Addélice Swid - 449€

Techne TE-10D Immersion Circulator ~1200$

My sous vide circulator fulfills all my requirements and Im VERY satisfied with the result!

Free standing:                                                                                             Running in air-insulated plastic box:

DIY sous vide immersion circulator, sestos d1s 220         sous vide circulator plastic box

Running in regular pot:

sous vide circulator in pot

The temperature stability is excellent, between +/- 0.3 degrees at most. It would probably improve a bit with a better temperature sensor than my cheep china-made PT100.

Getting components

I bought most of my stuff on ebay and Conrad.se (German company), but you will be able find theses components (or equivalent) on many other sites.

Main components list:

- Travel water boiler 350W, ebay: ebay
- PID controler and PT100 sensor, SESTOS D1S-2R-220 (2R = built-in relay), google it!
- Indoor submersible pump, Conrad: Jebao AP333
- 2 Fuse holders 5x20mm, Conrad: 526245-I5 (R3-46B)
- On/Off switch, Conrad: ROCKER SWITCH R13-208B2-02 RD250VAC
- Plastic case, Conrad: PLASTIC CASE 1591ESBK
- Cable bolting, Conrad: CABLE BOLTING AGR16GY3 M16 RAL7001
- Stainless kitchen utensil rack, IKEA: ORDNING 301.317.16
- Two food-grade plastic boxes with one lid, Rusta (Swedish discount-style store): R box xs 11 liter

Misc. stuff that you might have laying around in the garage:

- Grounded Power cable
- 2 screws and wing-nuts
- Epoxy glue
- Cable-terminals and connectors
- Shrink-hose
- Furniture paws

Getting a water bath

To get a decent water volume and to preserve the heat in the water I used two plastic boxes. One inside the other one and with some furniture paws in between to create an insulating air space. In the lid I cut a hole with slight bigger diameter than the IKEA dish stand.



Getting heat

I decided to go with a heating element of 350W. Most heating elements from water boilers are quite powerful (1500-2000W). From what I've read I understood that it would be easier to maintain temperature stability with a less powerful element (slower increase of the temperature when the element is powered on, less overshoot). Another benefit was that the PID controller I choosed had a built-in relay capable of 3A. With a more powerful element I would have needed an external relay as well.

Getting temperature control

There is a lot of cheep PID controllers on eBay or dealextreme. After some intense research looking for other peoples experience, my choice became the SESTOS D1S-2R-220.
The SESTOS D1S-2R-220 is a clone of the Auberins SYL-2342.
The manual for the Auber unit is way much better than the poor manual for the SESTOS.

Getting wired

This is how I wired up my device. It's was pretty straight forward. I connected a protective ground since the components run on 240V and there is water involved.
If the chassis or water in some way would be conductive there is no risk of getting electrocution.


 SESTOS d1s 220-vr
Many DIY people use ordinary household boxes as a container but I went with a dedicated box for electronics. Such boxes are much more robust.
Since this circulator is standing in a steaming water bath I was very careful with sealing the box to protect the inside electronics from moisture.

Getting circulation


First solution:

My first approach to obtain circulation was to put a small aquarium air pump (a fish tank air pump YB-100, off eBay) into the box and an oxygen-stone below the heater, to create many small bubbles.
Water was filled up to just above the edge of the three holes that I've cut out in the stand. The bubbles created a rich flow of water which effectively flowed through the holes. I scraped this solution later on.

Here's everything fitted inside the box:

SESTOS d1s 220-vr 

Oxygen stone, heater and three cut out holes:



However this bubble solution had two major issues:

1: NOISE!!

It was very annoying to hear the vibrations form the pump and the constant bubble noise for hours at a time. Vibrations spread into the pot even though I've put rubber damping around the pump. It would have worked better if the pump had been separate, standing on the kitchen counter. But I wanted my circulator to be a one-piece of equipment.

2: Oxygen stones does not like hot water!

At ~70 degrees C the stone unfortunately became converted into blue sand.
I also tried to plug the end of the silicone hose and making a lot of small holes in it with a heated needle. This solution worked just as good as the oxygen stone, but I still had the noise issue.

Final solution:

Getting tired of the noise from vibrations and bubbles the bubble solution was sent to the waste bin and I fitted the Jebao AP333 220V submersible pump instead. The pump is constantly running when the power switch is on.

The nozzle fits perfect into the holes in the dish stand:

Jebao ap333 

Low temperature pumps like the one I'm using will probably not last that long. So when this one gives up I'm standing between choosing either a hot-water pump from china, or I'll go with a aquarium pump of good quality.
I've read that some DIY Sous Vide people are using the "EHEIM 300 Compact" successfully.

Getting tuned

There are three steps that needs to be taken in order to make the controller work properly:


Setting correct sensor type

The D1S needs to know which type of sensor that is connected to it. If the sensor type does not match the set one you will get the error message "orAL" instead of a temperature reading. I used a 2-wire PT100 (more accurate versions use 3 wires). Good to know is that with a 2-wire sensor, terminal 4 and 5 on the D1S needs to be shortened or you will get the same error message.

1. Hold down the SET-button for two seconds to enter the functions menu.
2. Push the SET-button several times to jump to Input Sensor, "Sn".
3. Use the up or down buttons to set the sensor type (0 = K type, 21 = PT100).
4. Wait 10s to exit to normal mode, or press the SET and AT button at the same time to exit normal mode immediately.

Calibration of the sensor

My sensor was 2.3 degrees to low @ 60C, so there was a need to set an offset in the controller. I used a standard kitchen steak thermometer as a reference. Probably not that accurate but good enough for now.
Place the temp sensor from the D1S together with another thermometer in hot water. If your D1S and your reference thermometer's reading do not match you need to set a sensor offset in the D1S:

1. Hold down the SET-button for two seconds to enter the functions menu.
2. Push the SET-button several times to jump to Sensor Calibration, "SC".
3. Use the up or down buttons to set the offset.
4. Wait 10s to exit to normal mode, or press the SET and AT button at the same time to exit normal mode immediately.

Now you should have the same temperature readings on the controller and thermometer.

Auto tuning of the PID controller

In order to get the D1S to work properly it needs to have it's PID parameters adapted to your "sous vide environment". The by far easiest way to do this is to use the auto tune function in the D1S. The time this procedure takes depends on the volume of water, the power of the heating element and degree of insulation. In my setup it took around 20min.
The auto tuning should preferably be done around temperatures that you plan to use the D1S at. I did my auto tune at 60C in my insulated plastic box setup.

1. Pre-heat water in your box/pot to ~50-55C.
2. Set the wanted temperature on the D1S to 60C.
2. Hold down the SET-button for two seconds to enter the functions menu.
3. Push the SET-button several times to jump to Run mode, "run".
4. Use the up or down buttons to set the value to automatic, "1".
5. Push the SET-button several times to jump to Control Output, "CtrL".
6. Use the up or down buttons to set the AT value.
7. The auto-tune start procedure can be set to start in two ways:
    2) Set CtrL=1. You can start the auto-tune any time during the normal operation by pressing the AT button.
    1) Set CtrL=2. It will start automatically after 10s after exit to normal mode (I used this way).
8. Wait 10s to exit to normal mode, or press the SET and AT button at the same time to exit normal mode immediately.
9. When the auto tune procedure is started the display will start blinking "At".

Now the D1S's "OUT" LED starts to glow, indicating that the relay is active. It will continue to power the heating element for a couple of degrees above 60 before it turns off and lets the temperature drop a few degrees below 60. This procedure will be repeated 2-3 times before the D1S is tuned.

Now everyting is ready for some cooking!

Getting result

Now look at this fillet of beef!! This fillet spent 4 hours @ 58.0 degrees. Extremely juicy and full of flavor!



Regarding temperatures and cooking times there is a lot of information on the web. Personally I use theses two sites (in Swedish):

http://sousvideshop.se/hvad-er-sous-vide/sous-vide-tider-temperaturer/

http://sodersgourmet.se/images/Bloggbilder/Temperaturtabell Sous Vide.jpg

One thing to remember is to go easy on the spices. Since the flavors has nowhere to go in the vacuum sealed bag they will become very intense if you use to much spices. Which is good because you save spices and at the same time get more flavors than you wold do from traditional cooking. Here is an example of lamb chops ready to be cooked in a proper vacuum sealed bag, remember that it pays of to put some money on a descent vacuum sealer!