This gem comes from the 1976 printing of the Cub Scout Bear book.
Elective 16: Repairs (pg 146)
HOW TO THAW A PIPE: Don't set the house on fire by trying to thaw a frozen water pipe with a blowtorch.
First locate the frozen pipe by turning on the water faucets. Start thawing at the faucet and work back up the pipe. Be patient - it may take hours.
An electric iron will give you the hottest concentrated heat. You could also use a soldering iron or mother's hair dryer. Tie it or wire it to the faucet end of the pipe. Move it along as the pipe thaws. Make sure the iron doesn't touch any wood. It could start a fire.
In a tight place, use a soldering iron. It is slower but may fit in where nothing else will.
A warm-air hair dryer will do the job slowly and safely in hard to reach ares. Direct the air blast upward between the wall studs parallel to the frozen area.