Physics of freezing pipes.

Burst water pipes are caused by the expansion of freezing ice against the walls of the pipe, right? Wrong.

In a remarkable series of laboratory and field experiments, researchers at the University of Illinois have demonstrated that the actual cause of damage to freezing water pipes isn’t the force of the expanding ice on the pipe, but rather an extreme rise in water pressure downstream from the blockage.

Frozen Water Pipe RepairWater pressure can rise in freezing situations from about 40 pounds psi to over 4,000 pounds psi.

For example, copper pipe is exposed to unusually cold temperatures, and ice begins to form on the pipe’s inside walls. Since water volume expands by about 8 percent as it turns to ice, the ice formation eventually can completely block the water flow.

Water upstream from the blockage is able to flow back to its source, such as the street connection (if you do not have a water backflow device).  But the water downstream is trapped because the faucets are closed.  As the ice continues to form and expand, pressures downstream from the blockage skyrocket.  Because the entire section of pipe experiences the same elevated pressure, the failure can occur at any point, even within the heated space of the building.

Thaw frozen pipe.

  • Keep the faucet open. Running water through the pipe will help melt ice in the pipe.
  • Apply heat to the frozen section of pipe using an electric hair dryer, a portable space heater (kept away from flammable materials), an electric heating pad wrapped around the pipe, or wrap pipes with hot towels. Do NOT use open flame device like a blowtorch, kerosene or propane heater, charcoal stove.
  • If one pipe freezes, others may freeze, too. Check all faucets for low pressure.
  • If you cannot find or access the frozen area or if you cannot thaw the pipe, call PDM Plumbers. We have the tools and experience to get you back to normal fast.