Hold 6–12 inches away, keep moving. Works well on metal pipes. On PVC, keep temp below 140°F (60°C) — if the pipe gets too hot to touch, stop.
Only use UL-listed tape designed for drains (not supply lines). Wrap spirally around trap and pipe. Plug into GFCI. how to thaw a frozen drain
Use a standard hair dryer on a medium setting. Start heating from the faucet or drain opening and slowly work your way back toward the frozen section. Hold 6–12 inches away, keep moving