Wednesday, 15 December 2010

Frozen Water Pipes

Beware the unexpected cold snap or deep freeze. Frozen water pipes are a serious risk during very cold winter weather. When water freezes in a pipe it expands and can exert pressure over 2,000 pounds per square inch. This pressure is enough to rupture most any pipe filled with water which provides no place for the ice to expand. When the pipe bursts it will spill several hundred liters of water per hour, and that equates to thousands of pounds of damage to your home. Sad when you consider how easy it is to prevent a frozen water pipe.


Pipes are most susceptible to freezing when located:
  • In an outside wall
  • Under a sink on an outside wall
  • In an unheated crawlspace

In the situation where your pipe is frozen but not yet ruptured, you need to promptly thaw it out. There are a few thawing techniques we'll review depending on where the frozen pipe is located.

Never use a flame torch because of the fire hazard it creates. Open flame torches are the most common cause of pipe thawing related home fires.


When pipes are frozen you turn the faucet on and no water comes out or comes out in a trickle. As soon as you realize a pipe is frozen you need to take immediate action.
  • Open the faucet supplied by the frozen pipe even if you do not yet know where it is frozen.
  • Identify the frozen water supply pipe and find the location of the blockage
  • Follow the pipe back from the faucet to where it runs through cold areas such as an exterior wall, unheated crawl space or in some cases an unheated basement if the pipe is near an outside wall.
  • Often the frozen area of the pipe will be frosted or have ice on it. If the situation is getting critical the pipe may be slightly bulged or look slightly fissured.

When you find that the frozen pipe serving the faucet is behind a wall or ceiling, you've got a challenge on your hands. You have three choices:
  • Turn up the heat in the house and wait
  • Tear out the wall or ceiling section to get at the frozen section of pipe. Then thaw the pipe as an exposed pipe
  • Use an infrared lamp or lamps to assist in heating the wall section in front of where you think the frozen section is located. Infrared lamps are better than regular heat lamps because they pass through the air without heating it and will direct more energy to warming the wall and frozen pipe

If the frozen pipe is exposed, then you have several options available but first here are some notes to remember. When working on thawing the pipe leave the main water valve open (near your water meter) and remember to heat the pipe from the faucet toward the frozen area. This way, the water can flow out as the ice melts and the water pressure in the pipe will force the ice out once it melts sufficiently.

One of the best and safest ways to thaw the pipe is to heat the area with a high power hair dryer. Again, make sure to open the faucet and then heat the pipe working back from the faucet toward the frozen blockage. Also, if the pipe is close to the wall, place a cookie sheet behind the pipe to help radiate heat onto the back side of the pipe.

A heat lamp works well to heat an exposed pipe. You can use an infrared or incandescent heat lamp. As before, if the pipe is close to the wall, use a cookie sheet behind the pipe to help reflect heat onto the pipe.

If you have one of those small powerful heaters they work great when warming pipes under a kitchen or vanity base cabinet. Direct the heater onto the frozen section of pipe. It will work like a hair dryer on steroids!

Another technique is to use electric heat tape. This is a ribbon type wrap that has electrical heating elements in it. You wrap it around the pipe you want to heat, and plug it into the wall. The temperature is controlled with a thermostat and the heat tape heats the pipe.


There are a few things you can do to prevent the problem of freezing pipes from occurring again.
  • Leave the faucet drip slightly as a trickle. The dripping water will keep the water in the pipe from freezing.
  • Open kitchen base cabinet and let room air circulate.
  • Open kitchen base cabinet and place a small portable heater near or in it to heat the pipes
  • Wrap the problem pipe with electrical heat tape.
  • Insulate the problem pipes with foam insulation wrap, especially those that run through unheated spaces.
  • Temper the currently unheated crawlspace by placing a heater in the crawlspace. You just need to elevate the crawlspace temperature to modestly above freezing, about 2°C.

Source: Bob Formisano at

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