In terms of brewing with Ale yeasts, I understand that fermenter temps can increase up to 10 degrees, or more, than the ambient room temperature. As a "cheap" method for keeping the temperature of the fermenter as close as possible to the ambient temperature of the room, can I simply set the fermenter on a cooling duct? It would seem logical that the large surface area on the bottom of the fermenter would allow sufficient heat transfer to exchange at least some of the excess heat away from the fermenter.

Has anyone tried this before or can categorically state that this method is useless or shouldn't be attempted due to negative effects? While, perhaps, questionable in it's overall effectiveness, I can't think of anything that could potentially be detrimental to the yeast or fermentables using this method (assuming, of course, that the temperature is still within acceptable range for the yeast).

1 Answer 1


That is fine. A better idea, which I know some people do is to put the fermentor on the floor near the duct then cover both the duct and the fermentor with a large cardboard box. That way you don't have to cool the whole house to 60F. The box will get pretty cool itself.

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    Makes sense. Then the entire surface area of the fermenter acts as the heat exchanger. Good idea. Thanks.
    – Bill Craun
    Aug 27, 2011 at 22:02
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    You can get electronic temperature sensors for like $5, delivered, from Taiwan on eBay. They have a sensor on a 4 foot wire with a readout on the business end. Fermometers are ok, but you need to lift the box to see the temperature. I put the sensor on the carboy with a chunk of styrofoam to insulate the sensor from the air, then tape it in place. Works great.
    – Dale
    Aug 28, 2011 at 13:22

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