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Old 02-28-2013, 05:38 PM   #11
mdwilson
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I put mine at the same height as the heating element (about 1.5" from the bottom) at a location on the back side that was farthest away from the element. If I were to do it again, I would put it on the front side fairly close to the outlet valve. I don't have any problems with mine fluctuating, but during the mash the mash temp gets a couple of degrees high, as read by a separate bulb thermometer. I believe that the probe is currently located in a dead spot that does not get any circulation.

I like having the probe in the kettle because I use it to automatically switch from PID temp control to proportional control once the temp reaches 201F. I also use it to monitor the temp during cooling with the immersion chiller.

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Old 03-02-2013, 09:21 PM   #12
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I have it in a tee after the ball valve. Ball valve is under the false bottom that the bag sits on. That way you know what temperature wort you're pumping on top of the grain bed.

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Old 03-04-2013, 03:18 AM   #13
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I'm probably too late to help, but I put my probe in a T at the exit of the RIMS tube. During the mash the PID SV, PV and the brewmomenter at the bottom of the kettle all agreed dead nuts.

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Old 03-17-2013, 11:37 AM   #14
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well I have made the decision to put my probe in the pot opposite the element .
If it turns out wrong I am adding a sight gauge later anyway so the hole is not wasted if it is ok I will go with a tee for the pt100 and gauge together just need my bag and the cake rack to come and its trial time

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Old 03-27-2013, 08:39 PM   #15
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Placed mine in a tee on the pump output because mine is a gas controlled system and I wanted something removed from the burner. Guess it was a good choice since my system is spot on when running.

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Old 08-24-2013, 12:04 PM   #16
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well after a few brews I have tried the probe fitted in a tee with the sight glass but I believe it is too far away from the element and the take off ball valve(in a dead spot) as the temperature seems slow to rise when the pid applies heat and then shoots up (I have run auto tune),
so I have now moved it to a tee between the pickup tube and the ball valve and will try again.
I think that if i have the probe at the return sprinkler then the wort in the area under the bag support will be hotter as some temp would be lost in the journey through the pump and pipes.
Another question is what is more important the grain bed temperature or temperature of the wort below the CAKE RACK bag support.
I am wondering if the two will eventually even out anyway

thanks in advance Paul

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Old 08-29-2013, 01:34 AM   #17
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I can offer the following data point, as my system has evolved since my earlier reply in this thread:

I have a gas-fired BIAB system with a steamer basket in the (11G) kettle about 2" above the bottom, a pump, and recently had to replace my sight glass, so got a T for the sight glass with a temp probe reducer.

So, now I recirculate with temp readings both from the bottom of the kettle from the sight glass port and from the opposite end of the system - the T that connects to the lid of the kettle as the wort goes back in.

I got 2 deg F difference between the two with the pump valve open ~40-50%. (have only used the new-ish set-up one time). YMMV, and your tolerances may vary, but I don't find that to be enough difference to be concerned with, especially with a reasonably vigorous recirculation.

One hopes/assumes that the grain bed, bathed in the wort passing between these two points, has a correspondingly small temperature gradient. Ideally, a third temp probe right in there would settle the question, but not practical with BIAB.

Caveat for those with very tight tolerances: my two thermometers are made by different manufacturers, but do calibrate the same at boiling.

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Old 08-29-2013, 01:41 PM   #18
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Quote:
Originally Posted by breckenridge View Post
I have a gas-fired BIAB system with a steamer basket in the (11G) kettle about 2" above the bottom, a pump, and recently had to replace my sight glass, so got a T for the sight glass with a temp probe reducer.
I have almost the same system design but bagless. My mash tun pot is about 11g and wort circulates from the bottom through a sieve plate about 1 1/2" off the bottom, through the grain bed, through a top sieve plate, over flowing back into the main boiler (in which the mash tun sits). This is a two bucket system with the tun bucket sitting inside the main boiler bucket. I affectionately call it my "brew in a bucket" BIAB.

The main boiler is gas fired and temp is electronically controlled from the pump outlet which feeds the bottom of the mash tun. The pump's wort source is from the bottom of the main boiler. So circulation is: boiler bottom.. pump.. tun bottom.. grain.. tun top.. boiler top.. etc.

The flow is sampled immediately after the pump as it's forced into the bottom of the grain bed. I monitor the top of the grain bed at the output sieve with a second thermocouple which now gives me tun input and output temps.

In operation I find that once the main boiler temp reaches the set point, it takes about another ten minutes for the tun output to stabilize at that temp.

I had to experiment with the flow rate in this system to prevent peculation and channeling. Once I learned to slow things down to manage the channeling I discovered my temps fell inline much more quickly. Not sure I fully understand why but since I discovered this, my system has been a jewel to brew with.

For mashing at 152*F I typically heat my water to about 156*F, readjust the controller to 152*F, mash-in which typically drops the temp to a couple of degrees under the target. Wait about 10 minutes for the target temp to recover to the 152*F and start my mash clock. After that it takes about 10 minutes to see the top TC attain the 152*F. From that point on the mash temp doesn't vary more than about 1/2 degree from the target temp, at either TC.

So, this was a rather long way to suggest you play with your flow rate to optimize your temp control.

Cheers....
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Old 08-31-2013, 11:20 PM   #19
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Hi Sudz,

Getting a little off topic. I have a similar system (two vessel with flow from the bottom) with a bag in a bucket over my electric fired boil kettle. I have been playing with it and it works but I have had issues where the bag has clogged my return pipe at the top and have had overflow issues. I have been thinking of using two sieves like you are using.

Questions:
What thickness material and hole size are your sieves?
Have you had to reinforce them to keep the top one from bending under the pressure?
How do you hold the top one down?
Any wort volcano events?

Thanks,
Mike

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