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Home Brew Forums > Home Brewing Beer > Electric Brewing > Where is the best place to put the temperature sensor for a RIMS setup?
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Old 01-30-2013, 01:40 AM   #11
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Originally Posted by naamanf View Post
Why don't you propane heat the strike water and then put a removable insulation sleeve on it during the mash?
I do plan on wrapping some insulation around the kettle and just tie it on so I can remove it for the boil.
I want to use the RIMS tube to get the water up to temp for a couple of reasons. The cost of propane, which won't be offset by only going partially electric, but more important to me is that I can set it up and forget about it for a couple of hours while it gets hot and if I forget about it for longer than that there is no harm. This afternoon with no insulation and ambient temperature at around 55 degrees it a little less than 2.5 hours to get 9 gal to 160 degrees. It should be better than that with insulation.
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Old 01-30-2013, 04:53 PM   #12
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So for a set point of 160 the water was actually at 163? On the brewmometer as well as the PID controller? It sounds like you might need to let the system run in learning mode for a bit if its overshooting the set point.

It'll probably heat faster if you slow down the pump too

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Old 01-30-2013, 05:14 PM   #13
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So for a set point of 160 the water was actually at 163? On the brewmometer as well as the PID controller? It sounds like you might need to let the system run in learning mode for a bit if its overshooting the set point.

It'll probably heat faster if you slow down the pump too
Sounds right. In terms of flow rate for the pump, I would think there would be a "sweet spot" where you have slowed it to have optimal contact time with the element. Too fast will not heat as quickly, too slow could scorch. At least that is the theory.
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Old 01-31-2013, 02:00 AM   #14
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There can be several reasons for your PV to be set at 160F and over-running to 163F.

1. If the set display is at 160F and the actual display is at 163F then there is something wrong with the PV.

2. If the set display is at 160F and the temperature reaches 163F then starts dropping back down then you are monitoring the temperature at the wrong point, like at the RIMS inlet. Everyone forgets that when the RIMS heater turns on the temperature change is not instant, it takes time for the higher temperature to travel all the way through the mash tun. This is exact why you should monitor the temperature at the outlet of your RIMS tube. I have mine even closer - it's at the top of my RIMS tube.
http://www.instructables.com/id/Buil...el-RIMS-tube-/

3. If your PV is set to 160F and the temperature measured by a independent thermometer is at a constant 163F then one or the other is out of calibration. K type thermocouples can be as much as 2F off which is why the temperature of anything being controlled by a thermocouple needs to be independently verified. But one good thing about a K type thermocouple is once you know the offset you can count on it. In other words, of yours is +1/2 degree off it will always be +1/2 degree off.

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Old 01-31-2013, 10:37 PM   #15
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I found the thread where someone had a problem with overshooting and the solution was to auto tune. I did an auto tune and set the SV to 157 and the PV was dead nuts 157 as well as the Brewmometer at the bottom of the kettle. Life is good.
The sensor is in a T coming out of the top of the RIMS tube. I was going to put my senser in the RIMS tube like you did, but I got a 1.5" sensor instead of a 2.5" so it wouldn't have gotten all the way into the flow. The T screws into the place you have your sensor and my sensor is in the T so it is only about 2" farther downstream than your.
I'll post pictures if I ever bother to learn how.

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Old 01-31-2013, 10:43 PM   #16
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So for a set point of 160 the water was actually at 163? On the brewmometer as well as the PID controller? It sounds like you might need to let the system run in learning mode for a bit if its overshooting the set point.

It'll probably heat faster if you slow down the pump too
I put the PID in auto tune and let it run and that fixed the overshoot problem. Thanks.
I can see that the water coming out of the RIMS tube would be hotter with a slower flow rate, but there would be less of it so the overall time should be the same. I will probably have to slow down the rate when I actually have grain in the kettle to keep from compacting it, or so I have read.
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Old 02-01-2013, 01:24 AM   #17
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Glad that the learning mode sorted it out. PID can be a tricky thing to tune manually so when it works automatically it's always great.

The slower the flow rate the faster the water will heat up. The bigger the temperature change the faster it happens. You're probably also right that you won't be able to run at 9gpm whilst mashing.

I'd throttle the pump down and re-tune the PID setup, or at least check that it still works well at different flow rates, you probably won't want to be doing that when mashing.

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