Just yesterday, I bought a chest freezer and digital Johnson temp controller, and am EXTREMELY psyched. I think I'm going to make a pre-prohibition pilsner/classic american pilsner as my first lager. However, as psyched as I am to expand the breadth of my brewing domain, I am realizing that what I love more than anything are ales!

The ambient temp in my basement is around 60 degrees. I have a cream ale going right now (not in the chest freezer), but in reading "Brewing Classic Styles" I am realizing that I will need the freezer to hold a temp ABOVE the ambient temp in the basement to make some of these.

I know there is a separate wiki on temp control, but I wanted to know if anyone had any opinions on the best way to incorporate a heating element without risking barbequeing my dog while he's helpless in his crate due to an electrical fire. Things like the Brewbelt and the heating pads for inside a freezer make me nervous about fire risk and warping this $100 second-hand freezer I had to muscle down my vertical stairs.

Does anyone have any experience with the best methods/products?

Edit: I have looked at Brew Belts, Fermwrap, space heaters, and I believe there is a pad heater designed specifically to be put inside chest freezers for homebrewers (?). Space is a concern, as I had to lobby strongly just to have the chest freezer, otherwise I would be all over the aquarium heater.

4 Answers 4


I'm also looking for a similar solution - don't really want to mess about with extra water baths, and I have a controller that can control both a heater and a cooler.

I would think any low wattage pad would do the job - in the region of 30W-50W would be plenty to maintain the temperature inside the fridge. I think it makes sense you want the pad to be waterproof since there can be quite a bit of condensation in the fridge, and of course the accidental spill.

So far, I've found 2 types of heat mats that fit these parameters: seedling mats

seedling mat

and water reptile (vivarium) heat mats. reptile heat mat

(not all reptile mats are waterproof, so double-check.)

There is heat loss through the freezer walls in the range 5-15W, so a 20W mat would be a minimum, while a 50W mat is plenty to provide a step increase in temperature, such as drying out a saison, as well as maintaining the existing temperature.

There are some heat mats custom made for brewing. Searches for "brew heat pad" and "carboy heat mat" bring up homebrewing shops around the globe, and this one the US.

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I've used a $15 "aquarium heater" to get a Belgian beer up to 84F to fully dry it out. These gadgets are designed to be submerged all the time without any risk, so long as you follow the instructions. I put my carboy in a water bath, which was just a big cooler, and put the heater below the water level of the cooler. Seemed to work fine for me. I raised my temp from ambient 70F to 84F within a day or so I think.


My chest freezer is in a garage which is much colder than 60, probably in the 40s or 50s, and right now I have an ale fermenting at 68 degrees with no heating. My wort was at 64 degrees when I pitched the yeast, and the heat of fermentation got the temperature up a few degrees. So you might find that 60 degrees ambient is no problem.

If you do end up needing to warm thing up a bit, and are concerned with putting electronics in the freezer, you could perhaps do something like this pumped water solution but using a pond heater or aquarium heater in the water reservoir.

For my chest freezer, for getting tubes/wires in and out of the freezer, I built a wedge out of wood that props the door open a bit while still keeping it relatively air tight, giving me wood to drill through instead of having to modify the freezer.


went with a self-adhesive pad that sticks to the inside of the freezer. $40 shipped on Williams Brewing. Probably could have found something cheaper that would have worked with my temp controller, but being a complete electrical novice (and lazy), hopefully this will be a good solution. Folks over @ HBT gave this some pretty good reviews.

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