207 replies to this topic

[Chris Hennes]

That addresses part of the problem, but I still find that I have to fill the container higher than I would like, and therefore have to be quite careful about how much the water level is going to rise when I add the food. The margin for error is just a bit too small for my liking. I agree that the whole point of the device is "that it is small and simple and cheap" however, so if adding a few cm of depth brings the price over $200 it's not worth it.

[dcarch]

Here is an idea for SideKIC to consider:

The temperature sensor, the pump and the 300 watt heater all together are very light in weight.

The entire assembly can constructed to be floating on water. This way it will not matter what size vessel you are using, and how deep the water is. This will not increase manufacturing cost.

Having only the sensor cable and a small power line, it will be much easy to put a cover on to prevent evaporation for long cooking time. The way now it is designed to be hanging, it is difficult to cover the water bath.

dcarch

[gfweb]

Why not just dump the thing in the water and hang it by the cord? It could be at any depth that way.

Is t fully immersible?

[Chris Hennes]

Let the abuse begin... yeah, the beer cooler is quite a bit more than 10 liters, but it's very well insulated, and with the lid on there the SideKIC managed to raise the water the last 10°C (from 53°C to 63°C) in just under an hour. There's a brisket in there now for the next 72 hours. Fingers crossed...

[cbread]

Well, I haven't cooked with it yet, but I heated up a couple of gallons of water last night in a mock cooking run to 135 F. and am impressed. It did everything it should and nothing it shouldn't.

It sat against the side of the cooking vessel with better stability than I had expected and just seems quite solid.

I am less inclined to insist on clamps than I had previously. I'd still like them, but the design decision seems more valid than I had thought.

The control set up is extremely simple and very user friendly. I can't complement Duncan enough for that. Bravo. Easy as heck to set up. I liked the continuous temperature read out.

I'd like to see a slightly longer tether between the heating unit and the control unit.

I found myself wanting to have strain relief at each end of the tether.

I still want to see any future iteration of the design go deeper into the vessel and have more wiggle room between lowest and highest acceptable water levels.

Overall, though, it's a surprisingly rugged, solid feeling unit and not a toy.

Chris, I like your insulating top. Prompted by your fine example, I'm going to get a beer cooler very soon.

[cbread]

On the natural market for the SideKic - My guess is that sous vide is going to gradually work it's way into the mainstream household kitchen. I wish I could tell Duncan I believe that a good unit at low price alone will quickly make it mainstream but I think the idea will require time for the diffusion of knowledge about sous vide technique and theory.

I think that the cooking fanatics, hobbiests, and early adopters to be found in places like this forum are the real market for now.

[Doodad]

You guys with it in hand, do you think a small round cooler would be a way to go with it? Depth to place the items and let the circulator work on the top with lid placed on top although ajar?

[dcarch]

You guys with it in hand, do you think a small round cooler would be a way to go with it? Depth to place the items and let the circulator work on the top with lid placed on top although ajar?

Look carefully at Chris Hennes' cooler setup. You can see the water is covered with a piece of Styrofoam.

That's the way to do it. It sholudn't take you more than a couple of minutes to make one.

dcarch

[Chris Hennes]

I agree (obviously!) — the styrofoam top dramatically reduces evaporation: even with this unit's water-depth sensitivity issues I didn't have to add any water until this morning, my loss is around 1cm per day at 63°C.

ETA: it also lets me use a much larger-than-recommended water bath since it greatly reduces heat loss.

Edited by Chris Hennes, 10 February 2012 - 08:48 AM.

[Duncan Werner]

Hey, I knew what I was getting in for by jumping in on this forum. You guys are tough, but you're also obviously knowledgeable. You will be the toughest critics that I can face. Frankly you guys aren't really even the target market, but I really want to win you over - even if the current machine isn't good enough, I'm going to keep trying.

Who *is* the target market? There's not that many people interested in Sous Vide and I reckon we have a pretty representative sample of those who do on this board.

You're right, I think that was inartful on my part. I certainly didn't mean to give offense, and you guys are the target market. What I meant was that there are a handful of people on the vanguard - people who are knowledgeable, who tinker, who like to know how everything works - and these are the people who've been asking most of the questions.

While I think SV isn't mass-market yet, I'm trying to build something for the second wave - that is, people who want to experiment with cooking but for whom most of the stuff out there is too expensive or too complicated.

[Chris Hennes]

This morning the heater noise has increased considerably. You know the noise a drip coffee maker makes when its internal heater kicks on? It's that noise. It has gotten louder since yesterday, though, so I'm not sure what gives (I don't actually know the physics of what causes that noise, so I have no hypothesis here).

[Duncan Werner]

You might be hearing boiling water. It's possible that there's a small amount of water boiling just at the surface and around the heater. If so, you might also notice a small bit of steam generated around that area.

That would be because it's not transferring all the heat from the loop at the base, some is being transferred from the "stem". It likely changed because the water level is slightly lower or the environmental temperature is cooler. This will result in lower power efficiency. I would suggest adding some water, but I'm going to leave it to you (you're obviously putting the thing through it's paces).

Edit: if this is the case it will also increase the rate of evaporation.

Edited by Duncan Werner, 10 February 2012 - 09:50 AM.

[Chris Hennes]

How high can I go with the water? Is it a problem if it goes up to, or even covers, the top screens?

[Duncan Werner]

The water should be below the top of the top screen. I'm reading our manual and see that we are somewhat confusing about that, apologies. I generally have it just around the bottom of the top screen. Around the middle of the top screen would probably give you the best level to allow for some evaporation.

Note to self: mark water line on housing.

[Chris Hennes]

Increasing the water to be somewhere in the region of the middle of the upper screens didn't affect the noise.

[Duncan Werner]

Sorry for leading you down the wrong path, then. I still think that's what it is, although I have to get somewhere where I can hear that video a bit better. If there's a big difference between the environment and the water temp then it might happen at the surface regardless. I hope it's not too annoying.

[Chris Hennes]

No problem, we're debugging here. If everything worked right the first time I'd be out of a job! Alas, the noise is annoying enough that my wife will almost certainly demand the device be turned off when she gets home. I'll keep experimenting.

[Chris Hennes]

OK, starting from the knowledge that the device didn't make the noise yesterday I started guessing at things that might be different today: first, after long cooking maybe a condensate has built up somewhere in the non-submerged portion of the unit. Second, maybe something in my water has built up on the heater. Third, repeated heat cycling may have moved some internal parts. Fourth, the stars are in a slightly different alignment. Could be cosmic rays, too.

To test the first, I removed the device from the water and blew it dry. I put it back in and... viola. No more noise (so far, it's been two hours). Obviously by blowing warm air through the device I could have affected a number of other things, so this isn't a conclusive source of the problem, but it's a piece of evidence in that direction. Now, we see if the problem comes back tomorrow, and if the same thing fixes it.

[dcarch]

It sounds to me possibly the following:

When you cut Styrofoam, static electricity makes many small pieces sticking every where.

When you put the foam board in the water, the water drains away the static electricity, and small pieces of foam got dislodged and got stuck inside the pump impeller turbine housing and made that noise you heard.

Yes could also be due to the star constellations misalignment.

dcarch

Edited by dcarch, 10 February 2012 - 02:15 PM.

[Chris Hennes]

It wasn't the pump (which runs continuously), it was definitely the heater making the noise (which was intermittent). If you've ever listened to the noises a cheap drip coffee maker makes when it starts heating up the water you'll recognize what I was hearing. That doesn't mean that it wasn't foam bits interacting with the heater, however, which may also have gone away when blow dried.

Edited by Chris Hennes, 10 February 2012 - 02:20 PM.

[dcarch]

Then you may want to check this out: You will need an volt/ohm meter (Radio Shack, not very expensive).

If there is some electrical leakage inside the housing, which is very possible with inexpensive immersion heaters, and how it is connected to the other components inside, the electric power can start dicomposing the water (electrolysis) and make bubbling noise.

Set the meter at the lowest AC voltage range, with one probe in the water near the unit, and the other probe in the ground hole of the electric outlet. If you measure any voltage then you should not be using the unit at all.

dcarch

[Chris Hennes]

Nope, no voltage, I'm in no danger of electrocuting myself (at least, not from this project ).

[kayb]

A friend coincidentally sent me this today:

http://makeprojects....on-Cooker/471/1

Being something less than handy, and not possessing some of the requisite tools, I believe I'll stick with ordering a SideKic.

The thread has been fascinating. Thanks, y'all.

[Chris Hennes]

Duncan, is this a bang-bang control for the heater, or proportional?

[Duncan Werner]

Duncan, is this a bang-bang control for the heater, or proportional?

It's proportional.

[Chris Hennes]

The plot thickens... I ask because since I reset it this morning, it appears to be holding a much steadier temperature (perfectly steady, in fact... every time I've spot checked it today it has read exactly 63.0°C, 0.2°C higher than my Thermapen reads and probably within the margin of error). However, when it was making all the noise the temperature was fluctuating much more. So I just turned the temp up a couple degrees, and bang, it started making the noise again. It made the noise for maybe a minute, and then it died down, well before the temp had actually increased enough, so presumably it was still heating even though it was quiet. So this led me to a new hypothesis: what if somehow at some point the device got confused and started behaving more or less like a bang-bang controller, and was throwing full power at the heater whenever it needed any power? When I unplugged it to blow dry it, that reset whatever was wrong, and when I plugged it back in it went back to normal. Maybe the heater only makes that noise when it first starts heating all the way up, but is otherwise silent.

[Duncan Werner]

Well it definitely makes sense that it would be related to power. I said before that I thought it was boiling water on the exposed heater element and I still think that's the case (I could be wrong, but working hypothesis).

[Incidentally, there's a small icon on the screen, at the top-left, which shows the power output as a bar graph. It's not precise - the bar graph has 7 levels, while the actual power output is a 16-bit value - but it's a quick way to see what it's doing].

So you have a heat source - the heater - and you have a heat sink, the water. In power terms, a supply and a load. The heater is generating heat and that's being absorbed by the water. In most cases the heat will transfer efficiently - there's so much capacity in the water that all the heat is absorbed, and the heater (including any portion which is exposed) will be the same temperature as the water.

If the water line is low, relative to the heater, then all the heat generated won't be absorbed, and the heater will be hotter relative to the water. If the difference is large enough, just above the water line it will boil the water. Surface tension will pull a small film of water up the heater, to where it's hot, and will boil it.

This is not that unusual - in fact you can make it happen, if the heater is running, by slowly lifting it out until it's less and less in the water (if it's at full power, and about 1/2 of the "coil" is exposed, this will always happen). But ordinarily it shouldn't happen if the heater is submerged, because (1) the heat transfer is efficient, it's designed for that, and (2) again the water should have a pretty large heat capacity, which we're actually increasing by circulating it.

In the ordinary case, you can resolve this by adding more water so that the heater is better submerged. The design is such that as long as the water is above the middle of the bottom window, roughly, it will be sufficient. There may be slight variations, but the top of the bottom window is the ideal point.

Now if the heater is running at 1/2 or 1/4 power, even if it's still slightly exposed, you won't get this effect because there's less power to transfer. In your cooler setup I would guess that you could make this happen by adjusting the set point while it's running - set it to a few degrees above or below the actual water temperature - because it will adjust the heater to either 100% or 0%.

I don't mind telling you that we've been running around today trying to figure out what's happening to you. Generally, we're working on the theory that there's capacitance.

So going back to the power metaphor, we have a supply and a load. We assume that the load is resistive - that is, (loosely), it will absorb power. But if it's capacitive, then it will absorb some amount of power and then stop. At that point, it won't absorb any more power and you get the heat feedback loop I described above.

Why would that be the case? You're using a pretty big cooler, so there's a lot of water which would suggest just the opposite - that water should be able to absorb a lot of heat. However if you were running outside, in freezing weather, then it would be slightly different - the environmental temperature would "hold back" the transfer of heat, (because of the relative heat capacities of water and air). But that's not the case here. If there were a big difference between the environment and the set point that might still happen, but I don't think that's it either, unless your house is extremely cold.

But it could be the cooler. As it happens, my 16 quart cooler just came in so I can do some experimenting. Assume for the moment that the cooler itself is keeping the water cold. Then we try to heat the water, but it won't absorb the heat, and we get some feedback. There's a limit to the cooler's ability, so it doesn't happen when the heater is at 50%, but it does happen at 100%. And then, over time, the cooler's own temperature raises to 63C. At this point it won't resist the heat anymore, so we don't have that effect.

Sorry for the long post. I may know more (for example, I may know that I'm totally off-base) when I get a chance to run my cooler.

[Blues_Cookin]

Great start on the evaluations - I just got back from out of the country today, and will do some work with the SideKIC this weekend. Will let ya'll know if I see anything interesting beyond what Chris has reported on to date.

[Chris Hennes]

Thanks for the post, Duncan (no need to apologize for its length, you are nowhere near the eGullet record ). My update is that there is nothing to report: at the moment the heater has been running for a bit over eight hours since the reset and is completely rock solid at 63.0°C, running in stealth mode with two power bars lit up.

[Chris Hennes]

OK, my first long-time, low-temp cook with the SideKIC has come to a successful close. After that weird initial noise thing it settled into a constant temperature of 63.0°C and held it for 72 hours. The heater stayed at two bars nearly the whole time; when it kicked up to three on occasion there was some noise (of a different sort than before, but probably only different because it was a much lower power setting). The noise issue is going to require more investigation, but since it was dead silent for about 99% of the cooking time after the reset, I managed to stay married, and so far stand by my "buy" recommendation.