Never use an open flame torch to defrost pipes as this can damage the pipes or start a fire. Be sure to replace uncertified heat tape that is more than three years old with new tape that meets standards.
Step 1: Thawing a frozen pipe: Open the faucet fed by the frozen pipe. Before thawing a frozen pipe, be sure to know how to shut off the water supply to that pipe in the event of a crack or a break. Open the faucet that is fed by the frozen pipe. A flow of water will indicate that the pipe has been defrosted.
Step 2: Thawing a frozen pipe: Heat the pipe with a heat gun. Double up a sheet of aluminum foil and place it behind the pipe. This will protect the surrounding area from the heat and will help contain the heat to just around the frozen pipe. Use a heat gun or a hair dryer to heat the pipe. Take your time and work slowly. The warming pipe will melt the ice, and water flow should return to the open faucet.
Step 3: Protecting a pipe: Open the faucet to a trickle. Until a pipe has been properly protected from freezing, open the faucet fed by the pipe to allow a trickle a water. This will prevent the pipe from freezing until you can take the next steps to protect it.
Open the faucet to a trickle until the pipe is protected.
Step 4: Protecting a pipe: Use insulation, tape or foam. If the pipe runs along an outside wall, try to slide insulation in the space between the pipe and the wall to protect it from the cold. For additional insulation, use insulation tape to wrap the entire length of the pipe. A foam sleeve will also do the trick.
Step 5: Protecting a pipe: Open the cabinet doors. If the pipe prone to freezing is located in a cabinet or closet, keep the door open to allow warmer air from the room to circulate into the enclosure.
Keep cabinet doors open to allow warm air around the pipes.
Step 6: Protecting a pipe: Wrap the pipe in heating tape. For pipes subjected to extended freezing temperatures, use electrical heating tape. Following the instructions that came with the tape, install the tape along the pipe. Use electrical tape to hold it in place. If the heating tape must be covered, use a non-flammable fiberglass tape. The plastic wrap that came with the kit should be used to cover the fiberglass to prevent condensation from forming and dripping to the floor. Always plug the 3-prong heating tape plug into a 3-prong outlet for proper grounding. If an extension cord must be used, be sure it is heavy-duty and rated for the same amperage as the heating tape. Frequently check the pipe on cold days to be sure the steps have solved the problem.
Hold the heating tape in place with electrical tape.