Sous Vide Setup

WBegg

TVWBB Pro
Lately, I've been contemplating setting up my Heatermeter to allow for sous vide cooking. I finally broke down last night and came up with an enclosure design to house a 25 Amp SSR, a keystone jack for the "control" input from the HM, and an input and output for the AC power. I'm using it to simply control a slow cooker that I never use.

I also included an LED on the front panel to indicate when the system is getting "control" voltage (turning on the output).

The SSR is mounted so the bottom is exposed to allow for a bit of passive cooling, and is held to the case with 4 M6x1 Capscrews. The screw heads are covered with a printed "cap" that double as feet for the unit.

Here's some pics.





I've been letting it run the past few hours, and after about an hour of locking itself in, it's maintaining incredibly accurately.

I'll post the STL files if anyone is interested, but I need to make a few tweaks first. I meant to install a fuse holder, but I put the hole in the wrong place, and it interfered with the mounting screws.

Cheers,
W
 

DavidNP

TVWBB Member
neat idea....did you add/think about adding a pump to circulate? I know some have mentioned the hot spots without one. Are you using multiple probes or just one for the water temp?
 

WBegg

TVWBB Pro
neat idea....did you add/think about adding a pump to circulate? I know some have mentioned the hot spots without one. Are you using multiple probes or just one for the water temp?
A pump is really not needed with a slow cooker, as it tends to heat the volume fairly evenly. I did some checks at different points in the water volume and found no hot/cold spots. I'm just using one probe for the water temp. Since sous vide involves vacuum sealing the food, there's no way to monitor it's temp. The idea is, if the water is a certain temp, then eventually the food will be the same.
 

WBegg

TVWBB Pro
How's the heat? Those SSRs get quite hot and generally need a large heatsink.
Not bad at all, Steve. I've been playing close attention to it, and while it got slightly warm during the heat up phase, it never got any warmer than the heatermeter does. I think if I were running a few submersion heaters to heat a larger volume, then it would probably need some active cooling, or at least a proper heatsink. Since it's got up to temp, and running only 20% (2 seconds out of 10), there's no heat at all.
 

MKader

TVWBB Member
This is awesome. I've been using my HM to do a "ghetto" sous vide. I put a temp probe below and above the food in a pot. I regulate the temp using the ol' calibrated hand on the dial.
 

Bryan Mayland

TVWBB Honor Circle
Yeah I totally missed seeing this yesterday. That is amazing and very professional looking. Do you find the resolution of the output to be sufficient (10% at a time) in the "long pid" mode or should I more seriously consider taking up coding 1% output resolution to that mode?
 

WBegg

TVWBB Pro
Yeah I totally missed seeing this yesterday. That is amazing and very professional looking. Do you find the resolution of the output to be sufficient (10% at a time) in the "long pid" mode or should I more seriously consider taking up coding 1% output resolution to that mode?
Thanks Bryan. I wouldn't change a thing. I did a test yesterday, and after about an hour of "finding" itself, it settled in at 20% and never varied more than 0.1-0.2 of set point. A PID adjustment maybe for the initial overshoot?

 

WBegg

TVWBB Pro
Oh yeah, another tip. Never NEVER try to drill a probe hole in the top of your slow cooker lid if it's made of tempered glass, even with a proper glass drill bit. I found this out the hard way.

 

Steve_M

TVWBB Guru
Woops!

Yeah, tempered glass can't be drilled or cut after it's been tempered, only before. Makes a fun "boom" sound, though!
 

MKader

TVWBB Member
Great setup. Does the SSR just control the power going into the crock pot and you keep the crock pot setting on warm, low or high?

I wish I could test the hot spot theory with some work equipment. I was thinking you could easily build a "lid" with various holes in it and drop various length TC's all around. Cycle the temp a few times and see how it responds.
 
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SteveCK

TVWBB Pro
Looks great Will. I love printing stuff in white as well, it always comes out looking brilliant. Do you have the files up on thingiverse yet?
 

WBegg

TVWBB Pro
Don't have files up to thingiverse yet. Will try to get them up this Arvo. I cranked it up last night with some different PID settings (10, 0.007, 16) and it's running much better. Almost no overshoot at startup, and quick recovery with no overshoot when temp drops with the addition of food. I'm happy. I still have it running now, and I'll let it run the next 10 hours or so while I'm at work. You can see it here. The blip in the middle is where I added a cold potato to test temp recovery.

beggbq.servebeer.com/
 

SteveCK

TVWBB Pro
Graph is looking good Begg. I'm glad you brought up the sous vide thread as I had completely forgotten about this capability for the HeaterMeter. I was scrounging amazon today thinking about purchasing parts to build a custom tub with heater and the works but then decided maybe I could find a crockpot for cheap. I stumbled upon Sears/Kmart having an 8-qt model for just $25 so I thought I should share with the community: http://www.sears.com/hamilton-beach-8-qt-slow-cooker-red/p-00803291000P?sid=IDx01192011x000001&gclid=CjwKEAiAjfq2BRDpmdHmssaW5xsSJABToP4l0RBjMtrswFS0Ym9MJThkZCcmH1iI2n_yJ9YYB0bMMxoCI7_w_wcB&gclsrc=aw.ds

For reference, what size slow cooker are you using with those PID values?
 

DavidNP

TVWBB Member
I think I may try it out as well with HM.....but I wouldn't trust myself with DIY 1500w/15A SSR wiring...I like my house warm, not burnt ;) I found this device which looks like it would work off the servo wiring in HM....does HM have servo full on/off only mode? Adafruit also has a huge page on a sample project (also you can learn about PID there as well!)
 

WBegg

TVWBB Pro
I think I may try it out as well with HM.....but I wouldn't trust myself with DIY 1500w/15A SSR wiring...I like my house warm, not burnt ;) I found this device which looks like it would work off the servo wiring in HM....does HM have servo full on/off only mode? Adafruit also has a huge page on a sample project (also you can learn about PID there as well!)
That's a nice little unit, but $25 is a bit steep considering you can get an SSR for about $5, and that's probably what's inside that unit anyway.

Why run off servo? That unit can take a 12v control input, so why not run it off the fan output of the HM?
 
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WBegg

TVWBB Pro
Also, the servo receives pulses from the HM for it's position, so it's not set up to turn things on and off.
 

ChrisMueller

TVWBB Member
Hmm, I like the idea of hooking the fan output up to a relay switch that turns on and off a crockpot as it maintains the set temp. I've got some cheap ebay find digital temp controller that I have used in the past for that, but my Heatermeter would give me a pretty graph. I might have to wire that up.
 

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