Winterizing Guide: How to Find & Fix the Spots where Water Pipes are Likely to Freeze InspectAPedia® -
How to Find & Fix the Spots where Water Pipes are Likely to Freeze
How & Where to add heat to protect against pipe freezing: heat tapes, heaters, light bulbs, insulation
How to avoid freezing water supply pipes and drain piping, drains, traps, toilets, etc.
How to winterize pipes: frost protection for plumbing systems
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This article discusses the details of winterizing a building to prevent freezing pipes, focusing on how to find and fix cold spots that lead to frozen pipes in 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.
Guide to Finding and Correcting Freeze-Up Risk Points in buildings
You can do a lot to correct a freezing pipe problem in a building that is exposed to cold weather. Even in an occupied building pipes can freeze in some conditions. Here are some examples of places to look for freezing trouble and what to do about them:
Water pipes (both supply & drain) & hot water heating pipes or steam heat condensate pipes or building drains routed through un-heated areas or passing by areas exposed to cold drafts.
Check piping that runs along or near the building sills or building perimeter in basements, crawl spaces, attics.
Check water supply piping and horizontal drain lines and fixture traps in cold areas where building heat does not easily enter, such as the pipe chase at left.
Often you can simply cut an opening to let warm air enter such spots.
Look for drafts: On a cold, windy day, explore your home, especially the un-heated areas such as where pipes pass along or close to the building perimeter sills or foundation top in basements or crawl spaces. If the building has sections of floor that overhang lower parts of the building (such as a raised ranch) be sure the floor under-side is well-insulated and thoroughly sealed against drafts. When cold wind blows against a home which has an overhanging floor, wind against the building can force cold air into the wall cavity or even up into the building walls through a poorly-sealed under-side of the overhanging floor.
Explore the building on a cold windy day, looking for drafts: feel for cold drafts that blow on water piping or heating piping. Fix those drafts and you'll significantly reduce the chances of a frozen pipe. Fixing a draft means adding caulking, a plastic air barrier, using foam insulation, or other means to block un-wanted air flow into a building.
Look for places where pipes touch un-heated surfaces, such as foundation surfaces or framing. These may conduct heat away from the pipe and speed freezing at that point.
Look for the coldest of the un-heated areas where pipes run, such as an un-insulated attic, a pipe chase in a building corner, a crawl space (especially near foundation vents or other drafty spots), or as we explained just above, in a raised-ranch type home, where pipes run in the section of an upper floor which overhangs the building foundation (and may be poorly insulated).
Look for evidence that pipes have frozen before, and find out why the freeze occurred in that spot.
You may see a bulged pipe that didn't burst (if it burst it would have leaked and been repaired), or you may see a section of piping with one or even several pipe couplings soldered in place, a likely indicator that that section of piping has frozen before.
In our photo at left you can see that freezing has damaged the heating baseboard pipe and a copper pipe coupling has been used to make a repair by replacing a damaged section.
Plumbing fixtures in un-heated areas such as a bathroom or kitchen sink in a room that does not have its own heat source; in kitchens and bathrooms we may leave open vanity cabinet doors to permit warmer building air to reach pipes in those areas.
Plumbing faucets outdoors: traditional simple hose bibs or outdoor faucets can easily freeze where they pass through the building wall if the faucet is not shut off and drained; longer-stem frost-proof outdoor faucets are available and are used in new construction in most jurisdictions. Sketch at left showing the two types of outdoor water faucets is provided courtesy of Carson Dunlop.
These newer faucets make sure that the actual valve that turns off water flow is well inside the (supposedly heated) space.
If your outdoor faucet is the older type that is not frost-proof, you should be able to turn off water to that faucet and open a small screw fitting on the faucet body side to assist in draining that device when draining the building piping.
Even in a building where heat and water are being left on for the winter we make sure to find and use (or install if needed) the valve to turn off water to each outdoor faucet. Then we open the faucet to let it drain, leaving it open (and making sure it's not dripping from an indoor shutoff valve that is not working well).
Never leave a garden hose attached to your outdoor faucet in winter as water in the hose may add to the risk that the faucet will be freeze damaged.
How & Where to add Heat to Protect Plumbing Pipes or Components from Freezing
Adding heat to protect plumbing in un-heated areas such as crawl spaces: you may add heat either by installing a short section of heating baseboard, an extra opening cut in a warm air supply duct running through a crawl area, a small thermostatically-controlled electric heater set to operate only at low temperatures, or in small but cold areas, a simple light bulb may provide enough heat to prevent freezing.
Check these auxiliary heaters frequently to assure that the heat source is still working; be sure to respect fire safety when installing any heat source. Adding small point-sources of extra heat in a building to protect from freezing is likely to be more economical than running the central heating system to a higher temperature just to warm up a cold corner or two. Particularly if the thermostat set-back temperature results in the heating system turning on less often, adding point source heating may be needed.
We can add heat to protect plumbing and heating piping using any of the methods listed below and described in detail in this article:
Increase the flow of warm building air from the heated space into the cold corner or spot at risk of freezing by cutting one or more openings that let air circulate into the cold spot. In some bathrooms or kitchens we may simply leave the cabinet doors open to let room air reach sink plumbing.
Add a point-source of heat such as a tiny low-temperature-on electric heater, a short section of hot water heating baseboard, or by cutting an extra opening to let warm air blow out of a warm air supply duct into the cold area
Use heat tapes on piping in areas which are difficult to heat
Use a light bulb as a heat source
Add insulation on piping to protect it from freezing
Change heating system controls to continuously circulate the water inside of heating baseboards or radiators even when the boiler is not itself heating the water.
Leave water faucets open to a drip or very slow trickle: this is an emergency procedure that you may need to use if your building loses heat. Normally it's not a great idea to leave water running as we are wasting water, risking frozen drain lines, and if a septic system is installed, we risk flooding the septic system.
Increase warm air flow: Another way we've added heat to problem areas where pipes freeze is to simply make one or more openings to permit warm air to circulate from the building into the cold area. After finding freezing water pipes entering a bathroom located over a kitchen in a home with warm air heat, we cut an opening in the kitchen ceiling and installed a heating register there to make the hole look nice. Warm air rising from the kitchen proved sufficient to prevent a future freeze-up of the pipes in that location.
In any cold area where you are adding heat to avoid freezing pipes, the amount of heat you need to add will be reduced a lot if the cold area itself is insulated. Fiberglass insulation is fine for most building locations, but to reduce the risk of mold growth, we prefer to use solid foam insulation in areas like crawl spaces that are exposed to dampness.
Guide to Using Heat Tapes to Protect Pipes From Freezing
Using heat tapes to protect pipes from freezing: heat tapes are one of the simplest and more commonly used methods of protecting sections of water pipes from freezing.
But if the heat tape is not correctly installed it can be a fire hazard (as well as unreliable). Heat tape safety suggestions from the US CPSC are offered below.
Common locations where heating tapes are used on plumbing to prevent freezing pipes include:
Water pipes run through attics
Water pipes run through un-heated crawl spaces
Water pipes and equipment in un-heated garages
Water equipment in well pits
Water pipes running under porches
Some older or less costly models of heating tapes present a fire risk, particularly if the heating tape is crossed over itself. Be sure to read the product specifications, safety warnings, and installation guide before installing a heating tape on building piping of any kind.
Pipe Heat Tape Safety Guide from the US CPSC
The U.S. CPSC has provided safety recommendations for homeowners using heat tapes to help prevent fires:
Replace heat tapes that are older than three years
Use only heat tapes certified to meet recognized voluntary fire safety standards such as those provided by Underwriters Laboratories (UL), the Canadian Standards Association (CSA), and the Factory Mutual Research Corporation (FMRC).
Plug the grounded (3-prong) plug into a grounded GFCI (ground-fault circuit interrupter) protected electrical outlet
Don't cross the heat tape across itself unless the manufacturer says that's acceptable - crossed heat tapes can overheat and start a fire
Put the heating tape on the surface of the pipe to be protected from freezing, not on top of pipe insulation, and do not cover the heating tape with insulation unless the manufacturer says that's acceptable. Use only non-combustible insulation on pipes where heating tapes are installed (like fiberglass insulation). Foam or vinyl pipe insulation may catch on fire from a faulty heat tape or faulty heat tape installation.
Protect the sealed end-cap of the heat tape (see our photo above) from damage and water leaks which could cause a short circuit or fire.
Use heating tape only for the application approved for that particular heating tape, such as for use on piping. Some heat tapes are designed for use in gutters or driveways while others are designed for use on piping or fuel piping.
Be sure that the heat tape thermostat (if one is provided) is placed where the instructions say. For example some heat tape thermostats should be placed in contact with the pipe, others left hanging in air. (See our photo above)
Replace any heat tape that is discolored (a sign of overheating), cracked, melted, or damaged in any way.
Guide to Pipe Insulation to Prevent Freezing
Add Water Pipe insulation to prevent freezing: can be added to protect pipes routed through un-heated areas or near cold building corners. We particularly like to add slip-on foam pipe insulation where a plumbing line is run past a cold spot that is hard to warm up.
Some writers believe that if you insulate all of your water supply piping you won't have a frozen pipe problem. That may be a bit optimistic: we fear that a cold corner somewhere will be missed and left un insulated, or that a house left without heat for too long will get cold enough to freeze even an insulated pipe.
The advantage of insulating pipes is that it slows the rate at which a water pipe will freeze, possibly getting the pipe through the coldest part of the night and into a (hopefully) warmer daytime to warm-up again.
Remember, when insulating a water pipe, that you need to insulate all of it. Don't leave those awkward elbows or pipe tees un insulated.
Here is a speculative warning about relying on pipe insulation alone to avoid freezing, that is, we don't have hard science to back up this view: Insulation on a water pipe will protect the pipe from freezing during a brief very cold spell. But during a period of prolonged very cold nights and only moderately warmer days, we wonder if the insulation permits the pipes to accumulate "cold" rather than warmth, ultimately reaching the freezing point.
Plastic piping to resist freezing: modern plastic piping is considerably more tolerant of freezing without bursting than copper or steel water pipes. In a home intended for regular winterization some builders use exclusively plastic pipes to resist freeze damage. Be careful: even when freeze-tolerant piping is used, the piping connections, elbows, unions, couplings, and plumbing fixtures are still at risk of frost damage.
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"New Electric Heat Tapes Help Prevent Fires," US Consumer Product Safety Commission (CPSC) #00936
"Freezeproof Your House," Mike McClintock, Rodale's New Shelter, p. 30, October 1985 (approximate date)
"How to Winterize Your Pipes," Mike McClintock, Homeowners How-To Magazine, p. 59-62, Nov-Dec 1979.
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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
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