Authors pickup truck in front of a winterized and frozen-in building in upstate New York (C) Daniel FriedmanDe-Winterizing Guide
How to Restore Water Supply Piping, Drain Piping, Water Pumps, Tanks, Heaters to Use

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Steps to de-winterize a building:

This article explains how to de-winterize a building, including turning the water supply back on and getting heat, plumbing fixtures and other systems working.

We also discuss what problems to look for when de-winterizing a building. The articles at this website will answer most questions about freeze protection for piping and other building plumbing and heating system components: how to winterize a building to avoid frozen pipes, and how to thaw frozen water supply & drain piping, wells, & water tanks.

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Tips for Finding and Thawing Frozen Water or Heating Pipes

Frozen bath water supply piping (C) Daniel Friedman

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Article Contents

"Frozen pipes" does not mean that the entire length of plumbing or heating lines has become frozen. More often pipes freeze at one or more "cold spots" such as those we've discussed above.

Our photo shows building piping running through a poorly insulated area behind a shower. The combination of lack of building insulation, lack of pipe insulation, and the inability of building heat to enter this chase-way resulted in a frozen water pipe where we're shining our flashlight.

The steps below discuss how to find just where piping has frozen and how then to thaw it out safely.

We've used simple touch, by hand, feeling pipes for changed in the pipe temperature, or infra-red scanners to scan along piping to look for a drop in pipe temperature that may mark a frozen pipe location. If the heating pipes are frozen, often a section of the heating baseboard will be hot (hot water rising into the piping by convection if not forced by the circulator pump).

Some methods we've seen used to thaw frozen pipes, in our preferred order include:

  1. Turn off water supply at the main valve? If no water is running in the building and you leave the main valve open when pipes thaw your building may be flooded by leaks at burst pipes in ceilings, walls, or floors. But if water is still running in parts of the building take a look at different advice in steps 4 and 5 below.
  2. Turn up building heat to thaw frozen piping: this often works, but is the slowest, if safest, way to thaw frozen pipes. The risk is that you haven't found and warmed the frozen piping soon enough to prevent a burst water pipe.
  3. Use a hair dryer blower to warm frozen piping. A hair dryer is less likely to start a fire than other methods listed below, but nonetheless be watchful for sparks or debris and have a fire extinguisher handy. Just plug the hair dryer into a safe (GFCI) outlet and blow it back and forth along the suspected frozen pipe section.
  4. Open the faucets: if pipes are frozen you might reduce the chances of freeze-burst piping or reduce its extent by opening faucets. Allowing even a small amount of water (from the un-frozen pipe sections) to drain out of the building supply piping might reduce some of the in-pipe pressure even if no water is flowing from the faucet. - Building Research Council (1996). [ I'm not sure the strongest freezing forces are always horizontal along pipes. Details about the forces exerted by ice in or on buildings are

    Watch out: while some experts advise leaving faucets open or dripping to avoid freezing pipes, this advice is risky if the building drains are exposed to freezing. In many areas the building main drain exits above the frost line and can be exposed to very cold conditions. During normal plumbing use the surge of wastewater down the drain makes it past this cold spot without freezing.

    Really? Well yes, for normal plumbing systems and water use a main building drain above the frost line is normally empty except for passing surges of water warm enough not to freeze in passage. But a dripping faucet or running toilet, sending a small but continuous trickle of water down the drain can accumulate as ice until it expands, blocks the drain (leading to a sewage backup in the building) or until the drain line freezes and breaks.
  5. When water begins to flow you may hear some gurgling if it's a heating line, or if the frozen line was a water supply pipe the faucet or fixture that was not operating may begin to flow as soon as the pipe is just partly un-frozen, when a passage for water is opened enough to let water flow. Once this occurs, you can simply run more water to warm and free the remaining ice.

    Watch out: when water begins to flow in a building where pipes have been frozen there is a risk of serious building flooding and water damage, even costly mold damage if broken pipes leak and soak building areas. When pipes have been frozen and are now thawed and water is turned on, make an immediate and thorough building inspection, looking and listening for running water. If you find that a pipe section has burst you will want to shut water off immediately to avoid flood damage. More advice is at step 9 below.
  6. Use a heating tape to thaw a frozen section of piping. This step may take a little longer than the hair-dryer approach, but it has the advantage that you can properly install and leave the heating tape in place until you've done a better job of warming the area where the problem pipe runs.
  7. Use of a propane torch to thaw frozen piping?: this is a little faster than using a hair dryer blower, and also more dangerous. Open nearby faucets to let any steam or water vapor escape as the pipe thaws; work from the un-frozen pipe section back towards where you suspect the freeze-up has occurred; this will let you see water or steam begin to exit the pipe when you get to the ice.

    Watch out: using any heat source more powerful than a hair dryer risks setting your building on fire. If you are going to ignore this warningthat you may burn down the house, do not aim a torch at combustibles without adequate fire protection and stand-by fire extinguishers.

    A hidden hazard is that you may start a fire on the other side of something you are heating - in a place you cannot see. I watched a roofer, soldering copper roof flashing, set the roof structure on fire. By the time someone saw smoke outdoors the framing in the attic was lit afire.

    Do not direct the torch too close to soldered joints or you are likely to de-solder the joint, causing the pipe sections to separate, leading to a more serious leak than ever.

    Move the torch back and forth along the frozen pipe rapidly enough to avoid super-heating any small pipe section and thus reducing the chances of de-soldering a joint or causing unsafe pressure in the middle of a section of frozen piping.
  8. Use an electric welder to thaw frozen pipes: some plumbers and others hook up an electric welder to plumbing lines to thaw frozen pipes. To us this seems dangerous and we wouldn't try it.
  9. Listen and look for burst pipe leaks immediately: your frozen pipe may also have burst or separated at a solder connection. So as soon as you hear water flowing, search the building thoroughly to be double sure that a pipe has not burst.

    At PIPE FREEZE-UP POINTS we give some tips about where pipes often freeze, but you want to inspect the whole building, inside and out. (I once found water squirting through the building wall to the building exterior even though the inside looked as if there were no burst pipe problems. - DF)

    If you find that your thawed pipe is leaking in one or more places:
    1. Turn off the building water supply unless you can immediately find a shutoff valve that will just close water supply to the leaking pipe section
    2. Clean up the spilled water so you don't generate a mold contamination problem

How to Repair Water Supply or Drain Pipes that Burst or Leak

Heating baseboard freeze damage repaired (C) Daniel Friedman

Details about methods for repairing leaky water pipes or drain pipes in buildings are at LEAKY PIPE REPAIRS.

Excerpts are below.

Although we may have been careful to follow all of the best practices in winterizing a building, it is still possible that a pipe has frozen and burst during cold weather.

If a hot water heating pipe has frozen or a steam condensate heating pipe has frozen you won't see the leak until the building warms up but you may have trouble getting heat in some areas.

If a water supply pipe has frozen you will see the leak as soon as the building warms up and the frozen pipe thaws, unless water has been turned off.

If a drain pipe has frozen you'll notice it as the drain will be blocked. Worse will be the discovery of unsanitary water leaking when the piping thaws. Here are some tips for making repairs when these problems occur. A frozen fixture trap will be a smaller local leak that you should discover quickly by inspecting each fixture.

The exception which occurs commonly is a frozen bath shower trap in a bathroom over an unheated garage. Such traps or other plumbing leaks may drain into the garage ceiling where they cause more damage and take a bit longer to discover.

Find & repair the any frozen, leaky pipe breaks, cut out and replace that section of piping as described at LEAKY PIPE REPAIRS.

Tool To Repair Leaking Water Supply Piping Without Shutting off Water Main

This topic has been moved to and expanded at LEAKY PIPE REPAIRS where we describe methods for shutting off building water when the water main shutoff valvce is inoperative or missing.

Critical Steps in Returning a Winterized Building to Service

Although we may have been careful to follow all of the best practices in winterizing a building, it is still possible that a pipe has frozen and burst during cold weather. So the procedure of turning heat and water supply back on in a building needs to include some careful and frequent checks for leaks or unsafe (heating system) conditions. Never ever simply turn on water, heat, or even electricity in a building that has been shut-down without remaining to monitor for unsafe conditions, fire, smoke, improper heating system operation, or the presence of leaks.

Turning on the Heating System After a Building Has Been Winterized

Water damaged warm air furnace (C) Daniel Friedman

We prefer to get heat working again in the building if it has been shut down, before starting other plumbing work.

But look at the heating equipment before even thinking of turning it back on. If your furnace has been flooded as this one, it is possible that the system is unsafe and should not be turned back on. Before turning a heating system back on we need to:

If the heating system was a steam or hot water boiler, check the boiler carefully for leaks when it is restored to service.

Particularly some models of cast iron heating boilers may include boiler sections which loosen when the boiler spends months in a "cold" state, leading to boiler section leaks when the heater is filled and returned to service.

Restoring the Building Drain System after a Building Has Been Winterized or "freeze-proofed"

Goofy plumbing traps (C) Daniel Friedman

Remember to replace any plumbing traps that were removed from sinks, tubs, showers, etc. before trying out a fixture by turning on its faucets.

Then when you are ready to turn on the water supply, remember to run enough water into each fixture to fill the trap, then check the trap for leaks.

If your traps corroded, or if the trap arrangement is improper like this crazy collection of double-S-traps under a sink (photo at left), this is a good time to toss the old parts and have a plumber install a new trap that drains properly.

After you have turned on water supply, try each fixture by running a gallon or less of water into it. Then turn off the water and check the fixture trap for leaks.

When you're confident that you've restored the fixture trap without leaks, run water longer to test the building drain piping for blockage or leaks.

Stop, look, and listen for leaks.Before leaving the building that has been de-winterized, turn on one or more fixtures at a time, leave water running for a few minutes while you walk through the building looking and listening for evidence of a drain leak.

Watch out: Check for drain leaks both indoors and outside before leaving the building. Of course if you detect a leak in the drain system turn the water supply off immediately and remove any spills before starting the leak repair.

Staged Steps in Turning on Water Supply System to Minimize Water Leak Damage in buildings

Here we recommend that you follow a staged step by step approach to turning on water in a building where the water supply has been shut down over a winter or during a period of absence. The staged approach lets us check each building area and fixture one by one, minimizing the chances of extensive water damage even if a leak has occurred while the building was unattended.

Even for buildings located in areas not subject to freezing and burst pipes, a staged water turn-on approach is useful. A pipe may have been damaged or cut by building activities, a trap may have corroded through, or other plumbing damage may be present even if no freezing conditions occurred.

Step by Step Details of the staged water-on procedure can be read at  Turning on Water.

Articles on De-Winterizing Buildings


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