One of the most important things one can do to improve the quality of their homebrew is better control of the fermentation temp. I have used several things myself to accomplish this, from a standard heating pad (like you would use on a sore back) to my latest venture, Heat tape. I have been fermenting in a plastic nesting drum for a couple of years now and use heat tape and a PID controller to maintain fermenting temp in the winter.
Here is how I modified the heat tape to omit the built in thermostat.
Tools required
Soldering Iron and solder
Utility knife
electrical tape
wire strippers
small piece of wire
13 ft 26 Watt Heat-tape (obtained on sale in the spring)

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The large clear bulbous looking thing with the cord sticking out one end is the thermostat. Typically these are a bi-metallic switch that turns on just above freezing.

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I use a utility knife and cut lengthwise to expose the wires and thermostat.

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Once the thermostat is exposed locate where the black wire is riveted to the thermostat and solder one end of your small piece of wire.

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Reduced: 72% of original size [ 800 x 600 ] - Click to view full image

Once that is in place we are going to bypass around the copper "arm" to the rivet on the other side and solder in place. Once everything was soldered in place I used my wire cutters to remove the resistor, capacitor and the neon bulb as they were no longer needed.

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Reduced: 72% of original size [ 800 x 600 ] - Click to view full image

Finally close up the slit with a piece of electrical tape that runs lengthwise and then wrap the whole thing to keep it closed.

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**You must have some type of temp control with this type of heater.** either a Ranco or a PID controller will work fine.
for installation to the fermenter I wrapped it around starting from the bottom working in tight spirals making sure that the tape never touched itself. I held it in place with the same silver reflective tape that I used to hold the bubble wrap insulation the fermenter is encased in. I now have two 10 gallon fermenters that use this type of heater and along with the PID controller that I use am able to achieve temp control of plus/minus 0.1* F.