Fermentation Temp Control (Heating and Cooling)

[RunBikeBrew]

I've got a Belgian Dubbel fermenting right now and I've had some trouble controlling the temperatures as accurately as I'd like. I would like to hold fermentation at 64F, then gradually increase (~1F/day) over a week. This got me thinking...

Here are the temperature control tools at my disposal:

1. Aquarium heater & water bath: min thermostat setting is around 67F

2. Son of Fermentation Chiller: max temp setting is the same as ambient (see #3)

3. Ambient conditions in my basement (T=61F)

The problem: how to control temperatures between 61F and 67F?

Complicating factors:

- Fermentation is exothermic, and apparently fairly nonlinear - i.e. warmer fermenation generates more heat, cooler fermentation generates less heat.

- This is a transient problem. I need to carefully balance heat input, heat lost, and heat generated...all while each varies with time and temperature.


If I leave the Dubbel unheated, it will drop to around ambient temp (61F, too cold). If I plug in the heater, it rises to 70F (too hot). Right now, I'm trying a relatively simple solution: I put the aquarium heater in a 1 gallon plastic bucket full of water, then suspend the bucket so that only about 1/3 of it is immersed in the "big" water bath. Hopefully, this lets some of the heat dissipate to the air and not heat the wort. We'll see...

The way to solve this problem would be to develop a system that senses the temp of the fermenter, then supplies heat or cold as appropriate to maintain temperature. Here's a thought: I could have a "main" water bath for the fermenter, a separate bucket with an aquarium heater, and another bucket with ice water. Then provide a control system that senses temp and pumps water from either the hot or cold reservoirs to control temp. However, I my existing thermostat mods only support controlling one side (i.e. heating or cooling). I suppose I could use two thermostats.

Any great ideas out there?

(The other way to solve this is to only brew beers that require ferm temps substantially above or below ambient temp. Looks like I need to do a lager...)


Update: Here's one solution: https://www.homebrewtalk.com/f51/side-side-fermentation-chamber-build-105054/#post1152770

 

[Budzu]

This sounds very similar to what I am planning. My system would provide cooling and heat, but with only two total containers (and a fridge).
My system will have a cold water res inside a fridge. This reservoir will feed a tank outside the fridge in which will be immersed my 2 carboys. It will be fed cold water on demand by a love controller. The love controller will also be able to switch on an aquarium heater which is also inside the tank with the carboys.
There is a small pump inside the cold water res which is switched by the love to provide cooling, and another small pump inside the tank with the carboys and heater. That second pump is always on, to evenly spread heat from the heater and to keep temps stable around the carboys.
The external fermenting tank is placed right outside the fridge and above level of the cold water res inside the fridge, and is allowed to drain via gravity when filled above a certain level.
So for this 10 gallon system you'd need: spare fridge, 2 small pumps, 1 dual function love control, a small (1-2 gallon) container for the fridge, a large rectangular rubbermaid (or rectangular cooler) with grommet or bulkhead for the drain mechanism, an aquarium heater, and some tubing.
I know it sounds expensive, but you really cannot beat the accuracy of water immersed temperature control.
These ideas are heavily borrowed and adapted from some other smart folks here at HBT. Hopefully its close to what you are wanting to do and gives you some good ideas!
Cheers and good luck

 

[Hilbert]

I bought a brew belt to raise up my ales. It has a thermometer in it that keeps it at a consistent 70 degrees. Works well for me. Can't use it on a glass carboy though. I don't always use it at 70 but I let it run until i get to the temp I want and then unplug and keep going like the etc. Not the most sophisticated model but it does the job as long as you don't mind keeping an eye on it.

Plus my basement is cool enough that it's basiclly impossible for the primary to ever get to 70 because the cool concrete fights it.

http://www.midwestsupplies.com/products/site_search.aspx?SearchStr=belt

 

[RunBikeBrew]

This sounds very similar to what I am planning. My system would provide cooling and heat, but with only two total containers (and a fridge).
My system will have a cold water res inside a fridge. This reservoir will feed a tank outside the fridge in which will be immersed my 2 carboys. It will be fed cold water on demand by a love controller. The love controller will also be able to switch on an aquarium heater which is also inside the tank with the carboys.
There is a small pump inside the cold water res which is switched by the love to provide cooling, and another small pump inside the tank with the carboys and heater. That second pump is always on, to evenly spread heat from the heater and to keep temps stable around the carboys.
The external fermenting tank is placed right outside the fridge and above level of the cold water res inside the fridge, and is allowed to drain via gravity when filled above a certain level.
So for this 10 gallon system you'd need: spare fridge, 2 small pumps, 1 dual function love control, a small (1-2 gallon) container for the fridge, a large rectangular rubbermaid (or rectangular cooler) with grommet or bulkhead for the drain mechanism, an aquarium heater, and some tubing.
I know it sounds expensive, but you really cannot beat the accuracy of water immersed temperature control.
These ideas are heavily borrowed and adapted from some other smart folks here at HBT. Hopefully its close to what you are wanting to do and gives you some good ideas!
Cheers and good luck

Your approach sounds very similar to what I'd like to do. I think I may build a box with a dual function Love controller with two power receptacles: one would provide power when "heating" was required by the controller; the other would provide power when "cooling" was required. This way, I can play around with how I actually provide hot and cold (e.g. fridge vs. ice water vs. fermentation chiller, etc.).

I think I want to build this, but with a Love controller:

http://morebeer.com/view_product/16664/102282/Ranco_Digital_Two-Stage_Temperature_Controller_-_Wired


In the meantime, my "suspended bucket" trick worked pretty well. Essentially, I just put some thermal resistance between the aquarium heater and the main water bath. This seemed to do a good job of keeping my temps stable below the lowest thermostat setting. (This is, however, only a single data point.)

 

[AnOldUR]

Not pretty, not efficient.

I duct taped a small heating pad to the back of the inside of my mini fridge and put it at its lowest heat setting to compensate for the 60 degree basement temperature. There's a Belgian Dark Strong Ale in there now that I've been slowly increasing the temperature on. There's a good six degree swing in the ambient temperature as the fridge cycles on and off, but there's enough mass in the wort that it holds steady at a couple degree below what ever is set on the temperature control.