How do you know your pipe is frozen? After a bitterly cold night, you turn on your tap and instead of a steady gush of water you get a sickly trickle followed by...nothing. Since water expands when it freezes -- and pipes don't -- a frozen pipe is in danger of bursting. It needs to be thawed.
First you need to find out where the pipe is frozen. Turn off the main water supply. This will prevent the water from gushing out once the pipe is thawed. Then open the taps in the house.
- If water isn't running anywhere in the house, a pipe near the water meter may be frozen. Touch the meter and the adjacent exposed pipes. If they are very cold, they are probably frozen.
- If water runs in only one part of the house, a pipe in an outside wall or un-insulated crawl space is probably frozen. Open kitchen and bathroom sink cabinets to allow warm air from the house to warm the pipes.
- Once you've found the frozen pipe, open the affected faucet all the way, and open other hot water faucets in the house. When the water is flowing in the affected pipe, close all the faucets to a trickle. Do not close the affected faucet until the pipe is completely thawed and the water flowing freely.
The safest -- and neatest -- thawing methods involve a gentle heat source hair dryer, heat lamp, or household iron. A propane torch or other open flame will heat the pipe too quickly and may cause it to explode. Some people recommend pouring boiling water over rags wrapped around a frozen pipe. The obvious drawback is that this method is messy. Never pour boiling water directly onto a frozen pipe.
When thawing pipes with a heat lamp or hair dryer always work from an open faucet toward the frozen area. This will keep steam from being trapped by ice and bursting the pipe. With the faucet open, you can see when the ice has melted. Do not use un-grounded electrical appliances outdoors, or near grounded water pipes.
To prevent pipes from freezing in the first place, wrap electrical heating cable around it--one turn every two feet--then cover the pipe with insulation to conserve the heat. Follow all directions on the heating cable and take special care not to overlap the cable. Plug in the cable when the temperatures drops below freezing. The same cable device can be used to thaw a pipe. -- Michigan State University Extension.
