If you need to unfreeze water pipes leave your faucets open slightly to help thaw out the pipes.
Unfreeze pipes in attic.
Thaw frozen pipe in a wall.
If you find a leak close the main shut off valve to your house and call a plumber immediately.
Water freezes at 32 degrees fahrenheit but indoor pipes are somewhat protected from outdoor temperature extremes even in unheated areas of the house like in the attic or garage.
Set a fan up to blow room temperature air at the cold wall.
Surprisingly both hot and cold pipes can be at risk.
Wrapping freezing pipes with thermostatically controlled heat tape from 50 to 200 depending on length is also an effective way to quickly thaw a trouble spot.
Use a space heater heat lamp or hair dryer to thaw the frozen length of pipe.
Open any cabinet doors or panels to expose the pipe to the warmer room air.
For fixing frozen pipes in an exterior wall without opening the wall take the following steps block wind from the outside of the wall as best you can.
Controlled by a thermostat to activate only when the attic temperature plunges dangerously low the tape typically consumes about 5 watts per foot.
Field tests of residential water systems showed that for uninsulated pipes installed in an unheated attic freezing began when the outside temperature fell to 20 f or below.
What to do if a pipe bursts.
If a span of pipe is particularly vulnerable to low temperatures electric pipe heating tape acts like an electric blanket for pipes to prevent freezing.
Otherwise you can thaw out the pipe by wrapping the pipe in a single layer of thermal tape or blowing air from a hair dryer back and forth across the pipe.