Home Brew Forums > Home Brewing Beer > DIY Projects > Brew Stands > RIMS circulation temp overshoot
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Old 01-27-2011, 07:33 AM   #1
Bru
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Default RIMS circulation temp overshoot

I have a 1500W low density RIMS tube with the temp probe installed on the wort "out" side.
My grain bed stays at the right temperature but wort circulating through the RIMS over shoots by about 2F.
For example if I set my desired temp to 151 the RIMS will turn on at 150.5 and turn off at 151 but the thermometer will continue to rise to about 153F before gradually falling back to 150.5 and the process starts over.

Considering the mash temp stays constant should I be concerned about the overshoot ?
Any ideas how to fix it ?


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Old 01-27-2011, 08:34 AM   #2
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Sounds dialed in to me. I have a herms setup and need to re-circ a degree or two hotter than mash temps to maintain.


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Old 01-27-2011, 02:06 PM   #3
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It sure sounds like your RIMS is doing exactly what it is designed to do.
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Old 01-27-2011, 02:33 PM   #4
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Sounds good to me. I'd only worry about the grain bed and fluctuations within.
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Old 01-27-2011, 03:12 PM   #5
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How are you controlling the element? Don't ask me to explain it, but with a BCS system the PID is adjustable (easy for some) to control any overshoot. You can watch it in action as see how the power to the element starts to throttle back as it reaches temperature. I'm not saying your finished product will show the 2F difference but it doesn't sound like something that can't be fixed with a setting or change in probe location.

I don't understand more than 2% of this http://en.wikipedia.org/w/index.php?...PID_controller but it might help you.
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Old 01-28-2011, 06:36 AM   #6
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Thanks for the replies all.
Im using a temp controller from RS Components.
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Old 01-31-2011, 11:48 AM   #7
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Mine stays pretty much dead on what I have it set at. How fast is your pump flowing I think dialing in your wort flow will help stabilize your temp not to fast not to slow.;

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Old 01-31-2011, 09:44 PM   #8
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Where is the temperature probe located?
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Old 02-01-2011, 03:50 AM   #9
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I use a PID from Auber Instruments. Given my current calibration, I have found that I have to set my temp 2 degrees below my target, let it overshoot, then about 20 minutes into the mash as the temperature has stabilized I can slowly raise the PID up the final 2 degrees. That generally keeps me right at the temperature I am looking for. I originally set my probe at the inlet to my RIMS tube, but have moved to directly in the mash. I found that given the thermal mass of all the external equipment the RIMS tube temperature fluctuates much more slowly. It can take up to 10 minutes for the 2 location to agree on the current temperature. The mash will rise at almost 1 degree every 45 seconds when the heater is continuously on, but the RIMS tube measurement reflects a 1.5 to 2 minute degree changes.

Personally, I do not worry about the temperature of the wort as much as the grist. My theory being that I am more worried about the enzymes in the grain. Whatever is in the wort is already dissolved, and does not need as much conversion. I know that most HERMS brewers are concerned about killing the enzymes by running the wort past a heater element. I always see efficiencies of 75 - 80%, and have never scorched anything. I do keep the pump running at all times.
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Old 02-01-2011, 07:14 AM   #10
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That makes sense. My probe is installed at the "out" side of the RIMS. Im tempted to move the probe to the MLT for reasons you state - more stability - but as its working Im going to leave it.


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