Protecting Against Frozen Pipes

Frozen pipes are one of the most common (and most preventable) cold-weather emergencies in southern New Hampshire homes. A burst pipe can dump hundreds of gallons of water into a finished basement before anyone notices. The good news is that the steps to prevent it are simple, and the steps to react quickly if it does happen are straightforward.

At A.J. LeBlanc Heating, our licensed plumbers respond to frozen and burst pipe calls across NH every winter. Here is what we tell customers ahead of every cold snap.

What causes pipes to freeze in a NH home

Frozen pipes happen when three conditions combine:

• Pipes located in unconditioned or poorly heated space (basements, crawlspaces, exterior walls, garages, attics)
• Little to no flow through the pipe (idle pipes freeze faster than active ones)
• Sustained sub-freezing temperatures, especially below 0°F for extended periods

The risk increases dramatically when the home's heating system is set far below normal (vacation setback), a wood stove or pellet stove is used as the primary heat (which can keep the central thermostat satisfied while rooms far from the stove run much colder), or a power outage shuts off the primary heat.

Prevention before a cold snap

Keep the primary heating system running

• Maintain at least 60°F throughout the home during cold weather, even if you are away.
• If you use a wood or pellet stove as your main heat source, keep the central boiler or furnace operating so all areas of the home stay protected, not just the room with the stove.
• Avoid large thermostat setbacks during extreme cold. The savings are not worth the frozen pipe risk.

Promote airflow to vulnerable plumbing

• Open cabinet doors under sinks on exterior walls so room air can reach the pipes.
• Open interior doors to spread heat through the home, especially to rooms over garages or near exterior corners.
• Keep garage doors closed if there is plumbing or heating equipment in the garage.

Add insulation to at-risk pipes

• Foam pipe insulation (a few dollars per length, tool-free install) on pipes in unheated basements, crawlspaces, and along exterior walls.
• Heat tape (electric warming cable) on the most vulnerable runs that cannot be insulated practically.
• Seal air leaks where pipes pass through exterior walls or into unheated spaces.

Let cold-vulnerable faucets drip

If a fixture has frozen in the past, or sits on an exterior wall, let it drip slowly during the worst overnight cold. Moving water is harder to freeze than standing water. A pencil-lead-thin stream is sufficient.

If you are away, do not turn the heat too far down

• Set the thermostat to at least 60°F, never lower during cold weather.
• Have someone check the home daily during prolonged absences in deep winter.
• If the house will be vacated for an extended period, consider shutting off the main water supply and draining the lines as a final precaution.

What to do when a pipe freezes

Find the frozen section

The frozen section is typically the run where water flow has stopped at a fixture. Common locations: under sinks on exterior walls, in basement ceilings near rim joists, in crawlspaces, along exterior walls in finished basements.

Thaw it carefully

• Open the faucet served by the frozen pipe so meltwater has somewhere to go.
• Apply heat gently with a hair dryer, heating pad, or space heater. Work from the faucet side toward the frozen section.
• Never use an open flame (torch, propane heater). Plumbing fires are a real and dangerous risk.
• Once water starts flowing, leave the faucet open at a small trickle until the pipe is fully thawed and you have addressed the cause.

What to do when a pipe bursts

A burst pipe is a real emergency. Act in this order:

1. Shut off the main water supply at the meter or where the line enters the home. Every household member should know where this is located.
2. Shut off the heating system if a hydronic (boiler) pipe burst. This stops circulation and reduces the leak rate. For zone-specific leaks, you can shut off just the affected zone.
3. Turn off electricity to areas where water has reached outlets or equipment.
4. Open faucets to relieve pressure and drain remaining water.
5. Call a licensed plumber. A.J. LeBlanc Heating provides 24/7 emergency service across southern NH.
6. Call your insurance carrier if there is significant water damage.

Schedule a winter readiness inspection

If you have had frozen pipes before, your home has known cold spots, or you simply want a plumber to look at vulnerable plumbing before the next cold snap, contact A.J. LeBlanc Heating. For 24/7 emergency service, call 603-623-0412. Serving New Hampshire families since 1928.

Frequently Asked Questions

At what temperature do pipes freeze?

The conventional rule is that the pipe environment needs to drop below 20°F for at least several hours before freezing becomes a real risk. Pipes in well-insulated interior walls of a heated home rarely freeze. Pipes in basements, crawlspaces, exterior walls, garages, and unheated rooms are the typical trouble spots.

Should I leave faucets dripping during a cold snap?

For at-risk fixtures (exterior walls, history of freezing), yes. A pencil-lead stream of cold water is enough to prevent freezing. Hot water taps benefit too.

Can I use a torch to thaw a frozen pipe?

No. Plumbing fires from torches are a real risk, especially in older walls with combustible insulation, paper-wrapped pipes, or wood framing. Use a hair dryer, heating pad, space heater, or call a plumber.

How do I shut off my main water supply?

The main shut-off is typically located where the water service enters the home, often near the water meter or pressure tank (for well systems). Locate yours before an emergency happens. If you cannot find it, your plumber can show you on the next service visit.

Will my insurance cover a burst pipe?

Most NH homeowner's policies cover sudden burst pipe damage, but not damage from chronic leaks or freezing in a vacant home where the heat was turned off. Check your specific policy.