Maintaining Fermentation Temps in Colder Weather

FermWrap Carboy Heater

Fermentation temperature has a lot to do with how your finished beer turns out.

For many of us, colder temperatures are on the way or already here.  You may need a boost to keep fermentation temperatures up.  Here’s a roundup of some of the available options.

FermWrap Carboy Heater

The FermWrap heater is attached to your fermenter using tape.  Directions say that it is okay to use this in conjunction with a carboy bag.  40 Watts.  Ability to raise temperature from 5 to 20 deg F from ambient.

Available from MoreBeer – Adventures in Homebrewing – Note: As of this posting only AIH has this in stock


Available from love2brew – Adventures in Homebrewing and Great Fermentations – Note that these may be slightly different designs with slightly different specifications.

Heat Pad for Beer and Wine Making homebrewing.lorg

You place your fermenter on top of top of this heating pad.

Description from Adventures in Homebrewing:  “This rigid plastic heat pad for your fermenters and carboys is the ideal solution for cold fermenting and brewing problems. This unit provides ideal temperature for year round brewing, fermenting, and wine making in cold conditions. Convenient and easy to use, simply place on a flat surface, put your fermenter or carboy on it and plug it in.  Supplies constant, steady convection heat (25 watts, 110v) without creating any hot spots.  Inexpensive to run.  Dimensions – 12.5″ x 12.5”

Heat Pad for Beer and Wine Making

Zoo Med ReptiTherm® Under Tank Heater

I use a reptile heating mat in my fermentation deep freeze when I need to warm the space up a bit.  Think of these as heating pads that are designed to operate constantly.

The mat I’m using is 9 Watts.  It has no trouble raising my fermentation deep freeze (located in my basement) by several degrees.  I use this throughout the year whenever I want to push fermentation temperatures higher.  I do not set my fermenter on my mat.  I use it only to warm up the ambient air inside my fermentation deep freeze.

Zoo Med manufactures three sizes of these mats.  The small is 8 watts, the medium is 16 watts and the large is 24 watts.  Here is the specifications page from the manufacturers website.

Zoo Med ReptiTherm Under Tank Heater, Small

Zoo Med ReptiTherm Under Tank Heater, Medium

Zoo Med ReptiTherm Under Tank Heater, Large

Also Consider: Ceramic Heat Emitters

Thanks to Google+ Friend Lucas for this tip!

Hydrofarm MT10006 9-by-19-1/2-Inch Seedling Heat Mat

Lucas Says: Hydrofarm heat mats for getting seedlings started are also a very affordable option. They make an inexpensive digital thermostat with a temp probe as well.  I live in Southern Colorado, one of the coldest places on the continent (-40° winters anyone?) and these have done the trick for me.

Hydrofarm MT10006 9-by-19-1/2-Inch Seedling Heat Mat

Hydrofarm MTPRTC Digital Thermostat for Heat Mats

Of course… Whatever route you decide, proceed with the caution.  Electricity and Heat in confined spaces can pose safety risks.  Always follow manufacturers instructions and safety guidelines.

Temp Controllers:

Johnson A419 Digital Temperature Controller

Digital, Wired, Single Stage.  This has the ability to control one device to maintain temperature.  By default, it’s configured to run a cooling device.  You can configure it to turn a heating device by changing the position of a jumper.

Johnson A419 Digital Temp Controller

Digital, Wired, Single Stage.  This dual stage controller can run both a heating and a cooling device.  This helps to fine tune fermentation temperature.

Ranco Wired

Elitech 110V All-Purpose Temperature Controller+ Sensor 2 Relay Output Thermostat Stc-1000

The STC-1000 is a very popular homebrewing temperature controller.  This is a dual stage controller.  That means it has the ability to control both a heating and cooling device.  Great for a kegerator or a fermentation chamber/deep freeze.  110 volt version, reads in deg C.

Elitech 110V All-Purpose Temperature Controller + Sensor 2 Relay Output Thermostat Stc-1000

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7 thoughts on “Maintaining Fermentation Temps in Colder Weather

    1. Chris Brewer

      I would go with the medium or large size. I think small could probably swing 5 degrees, but it would be a slower reaction than the medium or large versions.


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