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Fermentation Temperature Control

tom_hampton

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At the request of Durettd, I'm copying this from the brewpot thread:

Fermentation temp control:
I've done the quartz heater thing.  It works "okay".  But, as you point out...it takes a lot of "attention" to keep the temp regulated.  I like "set and forget" control systems.  I hate coming home to find my beer 5 degrees warmer than I thought...for one random reason or another. 

The following should cost a total of about $50 in materials:

1.  Go over to homebrewtalk.com and look in the DIY section for aquarium heater controller builds.  Get an STC-1000 (acquarium heater thermostat) and follow the instructions in the threads.  Get a real STC-1000 ($25-$35 on ebay or alibaba...I got 3 for $17 each)...some of the other ones look the same but aren't as nice.  The STC-1000 is a two stage controller so it has separate heat and cool signals and will turn on a heater or cooler, whichever is needed.  They can switch up to 10 amps.

2.  Place the temperature probe directly on the side of your fermenter and cover with some kind of insulation.  This allows you to directly measure the temperature of the BEER, rather than the air around the beer.  Beer can be anywhere from 0 to 10 degrees F above the surounding air.  During active fermentation it will be high...after it will be about the same.  The only thing you care about is the beer (not the air).

3.  Use a fermwrap or an eletric heating pad on LOW (I use heating pads because I can buy them at walmart for $12...I don't have to order it over the internet...and wait for it to ship), and wrap it directly around your fermenter(s).  The heating pad now directly applies heat to the beer, based on the temperature of the beer.

4.  Set your controller for 0.5 degC (basically 1 degF) swing.  Then set your desired temperature. 

5.  check on it once a day and record the temperature in your log book.  Adjust your temperature as desired for any particular schedule. 

The only other thing to make this work is a room that is about 5 degF COLDER than your desired fermentation temperatures.    The idea is the cold air in the room cools the beer off, and the heaters warm it up.  You can make several temperature controllers and then you can ferment more than one beer at a time....each can be at its own temperature. 

If you get a heating pad, be sure you get one that doesn't have an auto-shutoff timer....or, find out how to disable it if it does (like me). 


Durettd's questions center around cooling ideas because he lives in Florida...

I live in Dallas, Tx, so I understand the temperature issues of the South.  I just finished building a cold room in an unused coat closet using a $99 window AC, and an STC-1000 type digital controller.  I disabled the internal thermostat, and used the digital controller to bring the temp down.  I'm lowering the room temp 2 degC per day.  I'm down to 10C (50F), still running normally without freezing up. 
 
This is the best low cost option out there. I built myself three of these controllers and have been using them for over a year now. What a huge difference it has made in my beers.
 
I'm considering building a two-chamber beer cooler:

I'll install a window air conditioner, with its internal thermostat disabled and controlled with an external thermostat (Johnson Controls A419ABC-1C Electronic Temp Controller) - to cool a lagering chamber to 35 to 40 degrees F.

I'll cool the second chamber, for fermentation between 50 and 70 degrees F, with a heat exchanger - a 25' coil of 1/4" ID copper submerged in a tub of antifreeze in the cold chamber. I'll pump the cold antifreeze through a finned heat exchanger with a thermostatically-controlled fan in the fermentation chamber.

I saw the heat exchanger concept described using a freezer as the cold chamber. I've also read a description of using a window A/C unit to cool a large shed to lagering temperatures. Wish I could remember where.

The cold, lagering, chamber will hold four or five five-gallon kegs plus a CO2 cylinder, and the antifreeze container with heat exchanger coil.

The fermentation chamber will hold my 7.5 gallon heavy plastic conical. It will need to be high enough to allow it to gravity-feed into a keg.


Now, putting the plan into action:

I'm assuming I will build the thing out of plywood with thick foam insulation.

How can I build the interior to handle condensation, resist mold, and be easy to clean?

How do I disable the internal A/C thermostat?

Is disabling the thermostat a one-way street or can it be reversed? It's intended to cool the bed room during extended power outages after hurricanes, si I'd like to be able to return it to its primary use when needed.

Does anyone have any expreience with an antifreeze-based heat exchanger?

Does this sound like it has a snowball's chance in Miami of working?

Dan
 
How can I build the interior to handle condensation, resist mold, and be easy to clean?

Since an air conditioner is basically a dehumidifier, it should just drip outside.  It's not like a chest freezer where the walls are colder than the air, causing moisture to condense.  You're cooling the air, and using it to cool the kegs and walls, so you shouldn't have anything condensation to worry about.

Is disabling the thermostat a one-way street or can it be reversed? ... I'd like to be able to return it to its primary use when needed.

I would suggest looking for a cheap AC unit that doesn't have a thermostat. Nothing to disable and you can dedicate it to brewing.

I did a quick search and came up with a Frigidaire FRA052XT7 as an example. Set to high, plug it into the Johnson controller, and you're good to go.

Does this sound like it has a snowball's chance in Miami of working?

Hell yeah! Post some pictures when you're done!



 
Just wanted to add that you're talking about a small, insulated space. So you don't need a ton of BTUs. Could probably get away with 5000.
 
  I believe the "shed" article was on homebrewtalk.  They used Fiberglass re-enforced plastic (frp) bathroom 4' x 8' panels on the interior.  This is something I want to set up in my basement.
 
Brewshed link:  http://www.mrmalty.com/brewstuff.php

I think you will have difficulty using an AC unit to get below 50F in Florida.  I live in Dallas, which is humid..but, not as humid as Miami.  My AC unit freezes up if I try and go below 50F.  I've got some ideas about how to fix that, but I haven't had a chance to test it.

 
If you get an AC with a mechanical thermostat, they are quite easy to bypass...without damaging the unit. 

When you install the AC make sure there is a slight, downward slope from the cold side to the hot side...to allow the water removed from the air to drain over to the hot side.  Otherwise it will pool in the cold side and eventually spill over back into your cold room. 
 
Use a 10amp SSR, solid state relay, to control your refrigeration unit and a thermostat to contol the SSR.  My buddy and I have built one to heat a box using a cheap, $15 thermostat to control the SSR which switches on the ceramic heater unit and a computer fan.  It worked very well during the cold months here in Reno.  The buddy got the SSR on ebay, two for $8.
 
I use a Haier 5000 btu window unit air conditioner to keep my kegerator cool.  It was very easy to override the built-in dial thermostat and let my Love TS-2 controller drive.  The box is about 29 cubic feet inside and is custom insulated with going from the inside out: fiberglass board, reflectix, 2 layers of foam board, plywood and bead board.  Believe it or not there's actually a sink on it, which probably does allow some heat in.  The air conditioner runs about once an hour for maybe 5 minutes, with a set point of 46F and a range of 3F.  It does not drip at all anymore since I did a better job of sealing around the air conditioner itself with great stuff.  This is in Maryland where we do get some humidity.

If I had more space I'd use the same basic concept to make a fermentation chamber.  The air conditioner is $100 and the controller is $52.

As it is, I keep my carboys in a water bath with microfiber rags on the side wicking water up.  A fan blowing on it keeps the bath in the 64 to 66F range and without the fan it's 70F.  This is in a room that stays pretty constant, temperature wise.
 
I use a small freezer chest and a temp controller that you can get a from your local brew shop or northern brewer. Since it wants to run at sub zero temps it cycles on / off seldomly once set point is reached. I see them all the time on Craig's list, sometimes as low as $25. And when your not fermenting you can use it to keep you kegged beer in it, and serve it up at any temp you want. If I need to keep the fermenter warm I add a 100w light bulb inside it. It doesn't take much to bump temp up in such a small insulated space. Or do a lager as the colder temps are to your advantage. It takes up very little space and will use less energy to get the job done.

Good luck, and Stay cool
 
I have a 19 cu ft and use a small dollar store fan,and gallon container to put probe and temp gauge in ,,,I have a temp swing of 4 drg at 32, and at 68 temps I run it at 65 so the temp does get above 68
The swing there is 64 to 68 ,,

One thing I have notice is air lock issues cycling this year , it so hot and burned up in Indiana ,,,,
We have had 100 plus days for weeks now ,, ,
The air locks reverse direction when closed , I keep them at a lower level with vodka , and only use the one piece one ,, you get suck back on the 3 piece ones , w/ better bottle anyway , that is the only issue I have with BBottles other that that I like um
WATCH those airlocks ,,,,,
 
Remember the KISS principle. Keep It Simple...
Bought a 25 cu ft chest freezer off craigslist for 20 bucks. Johnson Temp controller for 50. 70 dollars got me a chamber to ferment up to 6 carboys of ale in the hot summer. Lagers and kegs just get put in an extra fridge set around 45 f.
 
I use a Sears dorm fridge that does not have a freezer.  The carboy and blowoff fit nicely.

I use a piece of Reflectix and painters tape to securely attach the external temp controller (Johnson,  Analog) to the Better Bottle.  This ensures the controller is monitoring the carboy temp not the ambient temp. 

In the picture behind and below the blowoff is a 5" computer fan to circulate the air.  These fridges are cold in the back and warm near the door.  The fan evens out the temp. 

I set the controller 3-4 degrees below the desired fermentation temp which keeps the actively fermenting wort at the desired temp.

In the cold months, I wrap the carboy in Reflectix and slip in a heating pad.  I set the pad on medium and use a simple outlet timer to turn it off and on every 15 minutes or so.  I leave the temp prob attached to the carboy (opposite side of the heating pad) and let the fridge kick on as needed to keep the wort at temp.

This works great for me.

Oh, I prefer the front loading versus top loading as I can't hardly lift a 6G carboy out of a chest freezer. 

Cheers!
 

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