sous vide thread


 
Thinking about using my HM for Sous Vides, and for controlling an electric homebrew beer setup (240V SSR). Couple of questions:

- not sure the ET-72/732 probes will play all that nice with water.. would it be possible to make your ones own probes with an equivalent thermistor (and maybe perform some calibration adjustments in software)?
- is it possible to control the SSR output by % (for the boil kettle, run at 80% or something so the boil isn't 'too' rolling)

I seem to remember Bryan being into homebrew, so hopefully this can be a really great multi-tasker!

Cheers,

Tim
 
The probes are fine if you don't totally submerge them, I just wedge mine in between the lid of my crock pot lid so it's not fully in the bath and it seems to be fine.
 
Thanks for the heads up. That sounds like it'll work great for the sous vides, but not sure in the brewing environment they'll last as long. I wonder if I can seal up the connection to the 'braided cord' with something high temp (epoxy? JB weld) to make them last.

Cheers,
 
Yeah I wouldn't use JB weld either. You can get stainless "thermowells" with NPT ends for around $10, drill a hole in the pot and screw it on tight with a gasket. Then just insert a thermistor into that. I wouldn't use JB Weld on stuff that contacts food.

If you're driving a purely resistive load like a heater, you should be able to get away with running at the normal 500Hz output but it might create more heat in the SSR. The SSR is only going to toggle at most 120 times a second though because they usually have a zero-crossing circuit to only change state at 0V.
 
Bryan Mayland said:
If you're driving a purely resistive load like a heater, you should be able to get away with running at the normal 500Hz output but it might create more heat in the SSR. The SSR is only going to toggle at most 120 times a second though because they usually have a zero-crossing circuit to only change state at 0V.
Click to expand...

You've lost me here for sure.. I know if I set min/max fan to 100% I can get it to control the SSR / element when acheiving and/or maintaining the mash temp. When you say "running at the normal 500hz" you mean sending a PWM signal to the SSR which would potentially heat up the SSR? If I try this, am I able to manually set the fan speed (and therefore the PWM output) not based on any temps? Say make it 70% and then see how vigorous my boil is.. and adjust accordingly?

Sorry for being a bit dense here, but I'm not sure what happens when you send a PWM signal to the SSR? (Even rereading this thread a few times.. :p)

Thanks

Tim
 
If you send a PWM signal to the SSR it will try to turn on and off 500 times a second. The commercial PID controllers I have in my brewery are like 0.25Hz and some of the nicer models you can adjust between 0.1Hz all the way up to a whopping 1Hz. That tells me that you're probably not supposed to drive them at 500Hz. Whether this is bad for the SSR I have no idea.

You can set manual fan speed by entering a number between 0 and minus 100 (-100) into the setpoint or use the on-device menu to switch it to manual mode and use the up/down/left to adjust the speed.
 
Thanks Bryan, sounds like not running in "Sous Vides" mode (min/max to 100%) would be a bad (or potentially bad) idea when driving an SSR. Am I able to set the fan speed manually 'and' have min/max set to 100%? This would mean I'm driving the SSR a little more appropriately yet able to control the 'fan speed' (element power) manually instead of based on temperature.

I know I can get a $40 Auber PID to do this, but it would be fairly convenient to be able to do it all with the HM.

Thanks for your patience with me :)
 
Yeah min speed actually just sets the min % that HeaterMeter will turn the power on for. Anything less than that and it will do it by percentage of the percentage of a 10 second period. Example:

Min speed 50% current calculated 25% = Run at 50% for 5 seconds then be off for 5 seconds.
Min speed 100% current calculated 25% = Run at 100% for 2 seconds then be off for 8 seconds.

There's a 1 second resolution to the duration but I can't imagine it being any less accurate due to the large amount of time it takes to change temperatures.
 
Wow, I leave for 6 months, and this thread goes back active.

I think I mentioned it, but you should set your min fan speed to 99 or 100 %, which forces the heatermeter into "SRTP" mode as we called it a while back, which basically removes PWM control of the fan voltage, and gives it 100% power for a section of a 10 second cycle... so 10% will be on for 1 second of every 10. That makes SSRs much happier.

If you run them faster than 120Hz PWM, you lose determinism in your control... they will 'randomly' come on and off and you'll not have the actual control heat from your heating element that you expect. So, the solution is to make heatermeter think your fan is incapable of running under 100% power, and it goes into SRTP mode which is typically for voltages under 10% of 12v, which is not enough to run the microcontroller on the bldc fans. Make sense? I think this was covered in the big heatermeter thread before we split this topic out.

(A side note, running PWM at faster than 120hz on christmas lights makes for a really cool random flicker lightning sort of effect). Just a tip, you can split your power out and run some xmas lights or a lamp or something to see when your heater has power... that is, if your crock pot does not have a light.

The other thing worth mentioning as I caught up in the thread... My SSR only got "too hot" because I was running 12.5A through a 10 A relay. The new relays are much better, and are cheap too... 25A ones are cheap, they will not make so much heat. But still heat sink them.

I noticed some use of IEC connectors. Make sure your connectors are rated for the current that you are using. I am pretty sure most IEC cables/sockets are only rated at 10A. Typical croc pots and other heaters will pull 12.5 or so. So, grab a 'kill-a-watt' and see what you pull to make sure you don't overload your IEC cable and start a fire. If you get a heater that is 1200W, you'll pull 1200/120 = 10A. Any bigger and you need a bigger power cable.
 
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My HeaterMeter 4.0 seems to work fine including remote web access. I will be using it for an electric smoker instead of sous vide, but I guess the principle is closer to sous vide (electric element control) rather than fan control of a wood bbq.

I'm preparing the SSR & power wiring, an old (never used) Crydom 480V/40A model, which should be enough for European voltage :cool: Control circuit indicates 3-32VDC, HeaterMeter outputs 12V, perfect (I have it set to min fan speed = 100% as recommended here).

Haven't hooked up AC power yet, does anyone have an idea what the output resistance should be across the switched SSR pins when the control side is on? It doesn't seem to change from 2M-ohm when I apply 12VDC, which makes me a bit nervous. It could be some no-load ohmmeter related condition that I (as a non-EE) don't really understand... well, I guess I will know when I put 240VAC across it later today!

-dave

edit: google answered my question after all, http://www.crydom.com/en/Tech/Newsletters/Solid%20Statements%20-%20Bench%20Test%20an%20SSR.pdf => I will just try it without testing the relay.
 
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Question to any SSR Heatermeter users who have tried it on an electric bbq: what PID values are you using? I found that the default fan-based values in the software are not ideal for a solid-state-relay controlled electric system. Probably the normal "sous vide" values are also way off for a bbq, but I suspect there are others on here who have implemented electric bbq... would save me a day's work doing manual PID tuning ;-)
 
OK, finally had time to try some PID tuning on the SSR Heatermeter setup. I switched to Celsius at the same time (a bit easier for the natives I show it to here in Germany). My setup is a 2kw electric smoker element in a Landmann 11091 smoker.

First I got stable oscillation around a 70C setpoint, with P=30, B=8.

Then I tweaked it to B=8, P=14, I=0.12, D=30.​

With those settings I got a pretty stable result with low overshoot and no steady state error when changing setpoint. I haven't tried it at higher temps yet, but it works waaay better than the default values (which are fine tuned for a fan-on-charcoal setup and not SSR).
 
Okay, first Hi! Its been awhile :)

Secondly, I would like to use the HM to make a sous vide machine. What parts will I need exactly?

Box - 4x4x4 electrical box.
Outlet -Single.
C14 receptacle.
RCA jack.

What else will I need inside the box?
 
Just an SSR. I use a 10A SSR to control a 2A load and it has no heat issues, but depending on how much power you're going to push through it you might need a heatsink on it or some sort of cooling. Just hook the RCA jack to the input of the SSR, run one 110V wire directly to the plug and the other through the SSD.

I used a double outlet and cut the strip between them on the switched side so I could have one always-on jack and one switched. Instead of a C14 receptacle I just cut the end off the power cord and wired it in directly. Don't be crazy and use 20A parts, standard service is 15A and that's plenty and makes it a bit easier to work with the wire.
 
Bryan Mayland said:
Just an SSR. I use a 10A SSR to control a 2A load and it has no heat issues, but depending on how much power you're going to push through it you might need a heatsink on it or some sort of cooling. Just hook the RCA jack to the input of the SSR, run one 110V wire directly to the plug and the other through the SSD.

I used a double outlet and cut the strip between them on the switched side so I could have one always-on jack and one switched. Instead of a C14 receptacle I just cut the end off the power cord and wired it in directly. Don't be crazy and use 20A parts, standard service is 15A and that's plenty and makes it a bit easier to work with the wire.
Click to expand...

Im electrically stupid. Sorry. What is an SSR?
 
If you already have a heatermeter, you could spend $20-30 & have one that can not only control, but do the PID control + WIFI monitoring.
 
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