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Walts Malt
Joined: 27 Sep 2013 Posts: 119 Location: Farmington, MN
Drinking: Two Hearted Clone
Working on: Planning my Fall Brewing Schedule
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Link Posted: Sat Dec 02, 2017 1:01 am Post subject: STC-1000 & Thermowell |
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So I ferment in a sanke keg that has a corny keg lid welded into the top. Previously I just attached the probe from my STC-1000 to the side of the keg, but recently I added a thermowell to the corny lid that reaches into the middle of the beer. When fermenting a recent double IPA I'm seeing wider swings in the temp on the STC-1000 than I have in the past and that makes sense.
My question is that whether I'll need to switch to a PID if I want to use this thermowell, and if so, what would you suggest I use/build. I looked at some of the Brew Pi stuff, but at this point I'm not willing to spend the money that costs.
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kal Forum Administrator
Joined: 12 Dec 2010 Posts: 11121 Location: Ottawa, Canada
Drinking: Pub Ale, Electric Creamsicle, Mild, Pliny the Younger, Belgian Dark Strong, Weizen, Russian Imperial Stout, Black Butte Porter
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Walts Malt
Joined: 27 Sep 2013 Posts: 119 Location: Farmington, MN
Drinking: Two Hearted Clone
Working on: Planning my Fall Brewing Schedule
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Link Posted: Tue Dec 05, 2017 1:44 am Post subject: |
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Another question that I have is related to the wide swings I’m seeing in temps when using the STC-1000 with the probe in a thermowell. It just seems to swing back and forth and never settle in near the fermentation temp. Is this going to affect the end product. Was I actually better off just taping it to the side? I thought a thermowell might give me more stability and accuracy, it just seems like it’s gotten worse.
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SD Endorf
Joined: 24 Apr 2015 Posts: 88
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Link Posted: Tue Dec 05, 2017 2:46 am Post subject: |
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Walts Malt wrote: | Another question that I have is related to the wide swings I’m seeing in temps when using the STC-1000 with the probe in a thermowell. It just seems to swing back and forth and never settle in near the fermentation temp. Is this going to affect the end product. Was I actually better off just taping it to the side? I thought a thermowell might give me more stability and accuracy, it just seems like it’s gotten worse. |
Since the STC-1000 controls both hot and cold, you might look at what you're using as your heat source.
I had the same problem, fermenting in a fridge using a similar Ranco 2 stage controller.
If temp got too low, the controller kicked on a heater I had inside the fridge.
The heater was too warm, pushing the inside air too hot. The warm air heats your keg from the outside in. By the time the adjustment is made to the probe in the middle of the thermowell, it's way to warm. The air inside the fridge keeps heating and eventually the fridge kicks in, thus starting the temp swing cycle all over again.
The problem was solved by switching to a very small ceramic heater as the heat source. Though I suppose the same can be accomplished with an electronic heat wrap of some sort.
However if the temp swings are not caused by a heat source, then the differential on your controller simply needs to be adjusted to kick the cold in sooner.
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Tungsten
Joined: 06 Dec 2014 Posts: 318 Location: Buffalo, NY
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Link Posted: Tue Dec 05, 2017 6:12 pm Post subject: |
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kal wrote: | A simple on/off temp controller that doesn't look at rate of change (like your STC-1000) is fine for fermentation. It's what most people will use for fermenting. It's what fridges use too (if the temp's too high, turn on the compressor). No need for a PID that looks at rate of change. |
I agree, but I'd take it a step further and say you don't want a PID for fermentation control as you're describing. You know how a PID turns on and off an element fairly quickly and constantly throughout a mash? Imagine doing that on a compressor for a fridge or freezer. You'd destroy it in one batch.
Walts Malt wrote: | Another question that I have is related to the wide swings I’m seeing in temps when using the STC-1000 with the probe in a thermowell. It just seems to swing back and forth and never settle in near the fermentation temp. Is this going to affect the end product. Was I actually better off just taping it to the side? I thought a thermowell might give me more stability and accuracy, it just seems like it’s gotten worse. |
I think you're just seeing natural temp swings inside the beer that you weren't seeing before because you were taped to the outside. I assume that these wild swings are early on in the fermentation process? I tend to see that a little bit too as the yeast tends to heat up the entire batch somewhat fast, and then my chest freezer cools it down to compensate (usually followed by a heat up period with a fermwrap because the freezer is too strong). If you are later in the fermentation process then the temperature should stay more consistent.
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kal Forum Administrator
Joined: 12 Dec 2010 Posts: 11121 Location: Ottawa, Canada
Drinking: Pub Ale, Electric Creamsicle, Mild, Pliny the Younger, Belgian Dark Strong, Weizen, Russian Imperial Stout, Black Butte Porter
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Tungsten
Joined: 06 Dec 2014 Posts: 318 Location: Buffalo, NY
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Link Posted: Tue Dec 05, 2017 7:50 pm Post subject: |
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To Kal: +1
To the OP: An STC-1000 does have that setting (a delay for a compressor) available, though. I believe the setting is under setting "cd" (stands for Cool Delay). I think you can go much higher than 10 minutes if you want, but that's probably more than enough. I do NOT know what the default is. I certainly have mine set to the default and it might be 1 or 3 minutes... not sure. Worth looking into... even though that was unrelated to your original question, heh.
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Walts Malt
Joined: 27 Sep 2013 Posts: 119 Location: Farmington, MN
Drinking: Two Hearted Clone
Working on: Planning my Fall Brewing Schedule
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Link Posted: Sat Dec 09, 2017 2:21 am Post subject: |
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Thanks, Tungsten. I will check that out.
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