Is there any concern with warming up a fermentation by placing the bucket/carboy on an electric heating pad? Will it kill the yeast that settles on the bottom?

  • I don't have the rep yet for a comment, but this is just to echo what Scott says in his answer. I use a Fermwrap in tandem with a chest freezer, and a Ranco dual-stage temperature control unit. I also tape the temperature probe to the side of my carboy or bucket, with some bubble wrap to act as insulation, and can maintain temperatures within a very narrow range with this configuration. This also makes it very easy to ramp up temperatures or cold crash, as needed. I would think a heating pad would serve just as well as the Fermwrap. Note that if you're taping the probe (or the Fermwrap), you s Commented Sep 30, 2013 at 18:06

3 Answers 3


It depends upon how hot the heat pad gets - you want to use a pad that doesn't go above 30°C/85°F. I use a waterproof pad that was originally intended as a pet warmer. It has an adjustable thermostat to set the highest temperature it will reach. I have mine set to 25°C/75°F. So, even though it is connected to a temperature controller, the heat pad thermostat ensures that the underside of the carboy doesn't go above a safe temperature.


You'll want to ensure consistent temperatures. If your heating pad goes above seventy degrees Fahrenheit, you'll need a temperature controller to prevent it from going above. The ideal way to do this would be to have a heating pad that turns on the moment it is supplied power. I know a few you have to plug them in, turn them on, and then they'll run. You'll need a way to automatically have it start heating once it receives power.

Get a temperature controller. I use a Johnson Controls Digital Thermostat Control Unit. You'll need to affix the temperature probe to the side of your carboy/bucket. The ideal way to do this is to tape it to the side of the vessel, and place several layers worth of bubble wrap over it to act as insulation. If possible, try to avoid wrapping the pad over the bubble wrap, as that could heat the insulation and skew your reading. This way, the probe is getting only the temperature of the wort, and it'll turn on and off as the temperature hits the set thresholds.

Alternatively, I've heard good things about Fermwrap, but have never used one.

  • I use a heating pad marketed for homebrew like the one Northern Brewer sells (identical w/ different branding). Commented Sep 30, 2013 at 19:14
  • I use a heat pad made for homebrew, similar to Northern Brewer's: northernbrewer.com/shop/brewing/brewing-equipment/… It's hooked up to a Ranco temp controller, with the probe taped to fermenter like how Scott recommends, except I use a piece of foam from the craft store, not bubble wrap. Works great. I've got a pumpkin porter sitting on it right now. One caution, based on experience: don't use a heat pad meant for heating your bed. It's designed to cycle on/off automatically, won't allow consistent temperature control. Commented Sep 30, 2013 at 19:20

Another way to approach it is to put the fermenter in a large plastic tub and fill the tub with water. Put an aquarium heater in the water. You may want to put the heater on a timer. The water provides a thermal buffer to reduce temp swings.

  • When doing this, you'll want to ensure you have an adequate heater. I've heard stories of people having to ratchet up the temperatures to the mid-70's just to maintain a high 60's temp since the heater wasn't sized properly for the swamp cooler.
    – Scott
    Commented Sep 30, 2013 at 18:12

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