Where & How to Add Heat or Insulation to Prevent Frozen Pipes InspectAPedia® -
How to Add Heat, Heat Tapes, Insulation in 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 winterize pipes: frost protection for plumbing systems
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This article explains where, why, and how to add heat at cold problem spots to avoid freezing pipes. We discuss the safe use of heat tapes in buildings and warn about unsafe heating tapes and fire hazards. 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. We discuss various methods to give each spot in danger of freezing its own heat source. For example simple passive heating may be sufficient to avoid freezing in some locations: in kitchens and bathrooms we may leave open vanity cabinet doors to permit warmer building air to reach pipes in those areas.
Readers should also see Heat Tapes: Use on Roofs for Ice where we discuss outdoor use of heating tapes and de-icing cables to prevent ice dam leaks into buildings.
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.
Notice that the convector heater suspended from the crawl space ceiling (photo at left) has nothing combustible too close to the heater? Make sure that your added heat source does not create a fire risk.
Use heat tapes on piping in areas which are difficult to heat
Use a light bulb as a heat source. Keep light bulbs at least two feet from any combustibles. Even a light bulb can start a fire if it's too close to combustibles.
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.
Avoid a fire hazard with heating tapes: 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.
Heating tapes work fine on copper, brass, or galvanized iron piping, for both supply and drain piping but we prefer the type that use an automatic thermostat so that we are not using electricity unnecessarily. Be sure that the heat tape is properly installed and that you don't cover the thermostat nor place it in a warm rather than cold spot on the piping.
If your building plumbing pipes are plastic, such as PVC water piping, use only pipe heat tape that has an automatic thermostat to control the heat tape temperature. Otherwise a very hot heating tape may damage the piping or even cause a leak.
Sump pump and drain piping freeze protection: for indoor sump pumps and drains follow our advice above regarding metal vs. plastic piping and heat tape selection. If your sump pump drain line is exposed to severe cold above ground outdoors it may be difficult to keep it from freezing.
A common water entry problem we've seen is during spring thaw in northern climates. The ground surface may be frozen but melting snow sends water into building around and through foundation walls, especially if you've shoveled snow piled up against the foundation walls.
If the building is relying on a sump pump to remove foundation water then this is just the time we don't want our sump pump drain to freeze. If the drain can't be buried below the frost line all the way from the building to its final destination, we've had some success using heat cables intended for outdoor and wet conditions, even placing the tape inside the pipe in some installations. Follow the heating tape manufacturer's instructions and be sure to provide a means of easy tape replacement when needed - you don't want to have to dig up the entire line over again just to replace a heating tape on a sump pump drain.
Heating tape safety and proper installation are discussed just 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
Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
"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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