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Old 12-13-2010, 08:29 PM   #1
Lodovico's Avatar
Oct 2009
Posts: 925
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I'm getting some new equipment for christmas and i have a couple of questions. I'm getting a Johnson Temp. controller and I have an electric thermawrap for my fermenters. I was under the assumption that I would be able to use these together to bring my beer up to fermentation temps in the winter. I realize this means changing the jumpers inside the temp. controller.

After a discussion with one of my buddys, he is saying that those two pieces of equipment are pointless without also buying a thermowell. He said even if I insulate the probe and tape it to the bucket or carboy, I won't get anywhere close to an accurate temperature. He said that with the wrap plugged in the bucket/glass will get warmer much quicker than the liquid inside ( which makes sense to me).

Do any of you use a brew belt or therma wrap and a temp. controller without a Thermowell?? I'm curious on what people's experiences have been. Thanks!
Lodovico Brewing Co.

On Draft: Mild
On Draft: IPA
On Draft: Belgian Pale Ale
In Bottle: Brett Porter
In Bottle: Flanders Red
In Bottle: Oud Bruin
Fermentor: Biere De Garde
Fermentor: Belgian Amber Ale

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Old 12-13-2010, 09:06 PM   #2
Jan 2009
Posts: 4,998
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With all due respect, your buddy doesn't know what he's talking about. Your plan will work just fine. Attach the probe to the side of the fermenter and cover it with some insulation. The insulation probably isn't even needed, but I would do it anyway. You can also achieve the same effect using a cheap electric blanket to wrap the fermenter. Sure, the glass or bucket will initially be heated to a slightly higher temperature than the fermenting beer, but everything will soon equalize and all will be fine. Furthermore, having the probe inserted in a thermowell and inserted into the fermenting beer will definitely cause some much larger temperature swings as the response time will be slowed. When the temperature of the beer drops and the heat source kicks in, it will take a very long time to affect the probe in the thermowell and by that time you will be heading for a temperature overshoot. The same thing will happedn in reverse on the cooling down slope only with an undershoot. The whole point of placing the probe in direct contact with the outside of the fermenter is that it will be exposed to heat radiating from inside the fermenter. Covering the probe with some insulation allows it to more accurately monitor the fermenter temperature. I use a small ceramic heater inside a dead refrigerator as my winter fermentation chamber out in my unheated garage. The little ceramic heater comes on and warms up the chamber very quickly, but it also shuts down just as quickly and the chamber temp doesn't fluctuate much at all. The beer temp fluctuates even less due to it's large thermal mass. Just my opinion. YMMV as usual. Yes, move both jumpers to the closed position (jumpers cover both pins) for heating mode. You may want to set the controller differential fairly tight for best results. Set the anit-short cycle delay to zero. Controlling a resistance type heat source is much different than controlling a refrigeration compressor. You would want a wider differential and much longer Asd duration with a motor or compressor in order to protect it. The thermawrap or electric blanket doesn't benefit from that kind of protection.

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Old 12-13-2010, 09:22 PM   #3
Nov 2009
Asheville, NC
Posts: 2,827
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I've never used a thermawrap so I can't really comment on that.

I use one of these ceramic heat bulbs. heat bulb link

And I tape the probe to the side of my fermenter (better bottle). Works great very accurate control.

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