Did I get the wrong Temp controller?

In the Sous Vide Recipes Forum
Hey everyone. I'm just getting started with Sous Vide. I'm going the DIY method and have a Adcraft FW1200W on the way. I do have my temp controller, which is a Ranco ETC-111000, and I tried it out with my rice cooker as a test.

The temp controller works, but I think the probe is too slow to respond. I did an egg at 146F, but when the temp controller kicks off at 146, the temperature keeps going up to something like 151. The cooker is off, but I think the probe is just really delayed.

I've left he probe sit in the air so that it hits 72F and then I hold the probe in my fist and it takes a good 30 seconds or so for it to actually reach the temperature of my skin.

Just wanted to check with others to see if this makes sense, and if I just picked the wrong temp controller.

Thanks.
--Andrew


14 Replies So Far

Hi Andrew, hopefully someone more knowledgeable on the DIY side can take a crack at the specifics here but I can at least help a little bit. I used the Sous Vide Magic with a crock pot for quite a while and one of the most important things was to always preheat the water. It would do the same thing and overshoot by 5-15 degrees but once it stabilized it would hold the temperature very consistently. I'd give that a shot and see if it helps maintain a consistent temperature once it's heated the water.

Another variable... Because the instructions for the Ranco say to use a thermal well for immersion, I have a copper well that I made out of a tube. It does make contact with the side of the well, but maybe I sould just try it directly in the water next time.
Hey Jason. I was aware of the stabilizing need. I did let it stabalize for an hour or so, but it would still over shoot by about 5 degrees after the heat kicked on.
Shoot, that means the answer is beyond my knowledge, sorry! I'll shoot this to Twitter and Facebook to see if anyone there has ideas.
Thanks so much for your fast responses!

I've been searching for people using the ranco in their sous vide setup, but it seems like there are only a handful of results. No one has said anything about using a thermal well, so maybe that's my problem. I'll try again without the thermal well tonight.
If I end up buying a SVM as a replacement (assuming direct immersion fails on the ranco), what are the power ports on the back like? Does it have a standard US plug output (female), so that you plug your cooker directly in to it, or do you need an adapter?
The Sous Vide Magic has normal US power ports so it's nice and easy to use (for a non-tech person like me). You just plug it into the wall and plug the cooker directly into it.
The type of probe can certainly be important. As I recall thermocouples are significantly slower to respond than thermistors, which I believe the SVM uses. Mine certainly responds within a few seconds so sounds quite different.
Hmmm... well the specs say it's a thremistor. What seems wierd to me is that probe is not metal on the outside (or at least it doesn't look or feel like metal). Makes me wonder how conductive it is.

Does the SVM change instantly if you put the probe in to hot water?

Well, I'll report back tomorrow with the results of the direct immersion with the Ranco.
Well I got my Adcraft Food Warmer in today so I had to try it out. I decided to put the probe in an open plastic bag with the top of the bag out of the water. I figured the thinness of the bag and more contact area should give me the same results as putting the probe in the water directly.

I think since the Adcraft is so large and has more water than the rice cooker I'm having better success. I'm still not sure if the tolerances are acceptable.

I set the temp controller to 144F with a 1 degree differential (i.e. it will kick on at 143F). After stabilizing, I was seeing peaks at 146 or 147 and the min was 143F. Is a 2 or 3 degree overshoot too high or should that be OK. What are you seeing with the SVM?

I really appreciate your input.

--Andrew
Excuse the imperial measurements. Using a 30l boiling pot I
get 0.1 deg C variability using a SVM. Next to no overshoot, I have the proportional kick in at 10 deg off desired temp but with a slow cooker had it at 1 deg due to slower response time.

Very much doubt 2-3 deg will make a noticeable difference to meats, it might to eggs or other temp sensitive foods
I suspect it wasn't to do with your probe, although I'm not familiar with the Ranco equipment but when it switches your rice cooker off there is still quite a bit of energy on the heating element to increase the temperature. I'm not sure what type of logic the Ranco uses to determine when to switch on/off, most of the PID controllers use some sort of 'fuzzy' logic ie they learn the heating characteristics of the set up and adjust their performance to suit. On a sous vide circulator you can see the heating switching on and off quite quickly to maintain a steady temp.

As DaveyT says apart from eggs or cooking at very low temperatures, 2-3 degree cycling shouldn't make a lot of difference to the food.
Thanks Tony. That makes total sense. After doing a bit of digging I do see that there is no "learning" logic in the Ranco, which is probably why it was only $44(USD).

I wonder if the extra $100 is worth it for the SVM. I have a guy at my office willing to buy the Ranco for his home brewing setup, so I could recoup my money on the device and get a SVM.

Thoughts?

--Andrew
As a follow up. I've successfully cooked Chicken and Pork with the Ranco and the Adcraft with very good results. While the teamp controller doesn't "learn" like the SVM, it's great for the price (~$50 USD). Though if you are using a smaller cooker (like the 6 cup rice cooker I originally used) I'd probably recommend looking at the SVM.


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