Funny Idea for Mash Temp Regulation

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BryanEBIAB

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I might need a reality check.

I do eBIAB with an Avantco IC3500 induction plate and recirculation. At the 500 watt setting, the temp slowly climbs about 1degF every 5 minutes or so with the lid off. Currently, I have to monitor the temp and shut it off for a few minutes and turn it back on to 500-1200W depending on how distracted I had just been, wait a few minutes and shut it back off, repeat. It’s not productive to babysit and I’d like to improve.

I have a perfectly good inkbird that recently started collecting dust and I’m wondering if (or how best) I can use it for my mash. These Avantco induction plates are complicated to control directly (see this brave soul: Avantco IC3500 Induction Burner Hacked by an Arduino). My idea was to leave the induction plate on at 500W (lowest setting) and apply some cooling with the inkbird. Maybe it’s as simple as a fan blowing across the top that the inkbird turns on as the mash gets too warm.

What’s this crowd’s thoughts? TIA
 
I might need a reality check.

I do eBIAB with an Avantco IC3500 induction plate and recirculation. At the 500 watt setting, the temp slowly climbs about 1degF every 5 minutes or so with the lid off. Currently, I have to monitor the temp and shut it off for a few minutes and turn it back on to 500-1200W depending on how distracted I had just been, wait a few minutes and shut it back off, repeat. It’s not productive to babysit and I’d like to improve.

I have a perfectly good inkbird that recently started collecting dust and I’m wondering if (or how best) I can use it for my mash. These Avantco induction plates are complicated to control directly (see this brave soul: Avantco IC3500 Induction Burner Hacked by an Arduino). My idea was to leave the induction plate on at 500W (lowest setting) and apply some cooling with the inkbird. Maybe it’s as simple as a fan blowing across the top that the inkbird turns on as the mash gets too warm.

What’s this crowd’s thoughts? TIA

Why not set your induction plate at 500W and cycle the power on and off to it with the inkbird based on the temp?
 
Why not set your induction plate at 500W and cycle the power on and off to it with the inkbird based on the temp?
Ah, I missed a point: when the Avantco power cycles (unplug, plug in), it goes into ‘standby’ mode. You have to press the “on” button after pluging it back in.
 
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Ah, I missed a point: when the Avantco power cycles (unplug, plug in), it goes into ‘standby’ mode. You have to press the “on” button after plug-in it back in.

Can you open up the guts of the Avantco and cycle the hot leg of the induction coil directly? That way you could keep the computer on and only switch the inductor

That would require some contactors and a solid state relay and some safety circuitry though.. So you'd basically be building a control panel at that point though.

I don't think it would be too crazy hard to do though
 
When I had an induction setup, I would do what I called a "swoop mash". Inspired my the Duvel mashing process. I would start at low beta temps and put the induction burner on a very low setting. This would slowly raise the temperature of the mash. I would go from 140-144F to 170F over 70-90 minutes and be done. No need for monitoring and all of the temperature rests were covered. I did have a slow stir arm going which helped for sure.
 
I'm back at this and thought I'd update the thread with my thoughts/discoveries. I found a few more threads with valuable insights but especially this one in particular. I was very happy to see that when I popped open my Avantco IC3500, it looked virtually identical to the Avantco IC1800 model pictured. Description of the thermistor also matched closely.

What @TheMadKing said about maybe running the hot leg of the coil through the Inkbird STC1000 stuck with me. Unfortunately, it's some crazy high voltage running though there to produce the induction currents necessary for heating and I'd rather not mess with that! Plus, it turns out that the Inkbird is only rated up to 220V so I'm not sure what fireworks that might cause. Still, a more direct approach felt right. I also feel I should endorse @Bassman2003's 'swoop mash' suggestion because that is a wonderfully elegant solution! However, I'm compelled to tinker, like many of us here, so onward down the rabbit hole...

My thought is similar to the the post linked above in that the temperature sensor (thermistor) has potential to be very useful as a way to turn "off" the unit without cutting power completely and getting stuck in "stand by" mode. But I'm not satisfied with the accuracy the poster eventually got by just moving the probe to a better location. Therefore, I plan to run the thermistor through the Inkbird to either open the circuit or close it with a resistor in series (not sure if shorting it out would cause damage--would rather not try). I would then place the Inkbird's much more accurate and rugged probe inside my (new) thermowell reading the temperature of my recirculating mash.

But first I wanted to learn more about the thermistor. I pulled it out and read the resistance with a multimeter in ice water (230k ohms), room temperature (130k ohms), and near-boiling water (11k ohms). These readings show that the thermistor is "NTC" so as temp goes up, the resistance goes down and vice versa. Also, I wanted to confirm that a simple open circuit wouldn't screw up my plans so I turned on the unit with the sensor completely removed--and it worked! Well, at least in "heat" mode. I can also say goodbye to the over-heat protection safety feature so no leaving this thing unsupervised for any great length of time. Not like that happened much anyway.

So I think my next step is to wire something up like this: remove the thermistor and instead wire the leads to the COLD side of the Inkbird with an 11k resistor (or whatever I can find that works in my basement, honestly) wired in series. With the Avantco in "hold" mode, set the temp to anything lower than boiling. When the Inkbird's sensor gets below the set threshold, the cold side will switch OFF making the Avantco 'think' it's sensor is very cold and turn the coils ON. When the mash temp gets above the Inkbird's set temperature, the cold side will switch ON making the Avantco read about 11k ohms which it will interpret as being around boiling and therefore switch the coils OFF.

I'll report back. Hopefully there's a way to hack an Avantco IC3500 without having to get this involved.
 
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Well, the update is that while setting up a proof of concept, I accidentally grounded the sensor lead from the board and WELDED it to the side of the case. Looks like I blew a nearby capacitor. Probably won’t be reporting back again for a little bit.

Good news: this unit was already cracked and replaced via warranty so it’s (luckily) only my pride that’s hurt and not my wallet or capacity to brew beer.

To anyone reading this planning their own Avantco IC 3500 hack, beware: those 22 AWG leads in the temp sensor still hold 220v and a good wallop to anyone who’s not careful.
 

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