go to menards/home depot/ace and get the plug-in wrap wires.  it's like a flat extension cord that you wrap around the pipes.  it has a built in sensor that regulates the temp, not too hot.  I use them in a summer cottage during the winter so i don't have to blow the pipes out.  not a break since i started using them about 5 years ago.  cost about $25  will take a couple hours to thaw, but will keep them thawed.