Find the plug, then warm it
Pipe Thawing Service Denver
Safe Pipe Thawing & Ice Plug Location
Heat applied to the wrong twelve inches of pipe accomplishes nothing except burning an afternoon you don't have. Locating the ice comes first. Thawing it comes second. And the list of things that must never touch a frozen pipe is shorter, and more important, than either one.
- Locate the plug first
- Open the tap before heating
- Work backward from the fixture
- No open flame, ever
Finding the ice before you heat anything
Which fixture died tells you which branch to walk. Trace that line backward from the dead faucet toward the water heater or the manifold, and the plug will be in the coldest segment along the way. In practice that means an exterior wall cavity, a vented crawlspace, a garage ceiling with plumbing above it, a rim joist bay, an unheated addition, or the kitchen sink on the north side of a Denver bungalow where the supply runs outboard of what little insulation the wall has.
Then use your hands. Frozen pipe runs noticeably colder than pipe on either side of the plug, and copper often frosts or beads at that exact spot. Tapping along the run changes tone where the water is solid. A twenty-dollar infrared thermometer swept along a joist bay narrows a fifteen-foot run down to about two feet, which is the difference between an hour of patient warming and a wasted afternoon aimed at the wrong bay.
Behind finished drywall, don't start cutting. Warm the room hard, open the cabinet and vanity doors so house air reaches the chase, and give it time. If you still need to open a wall, an infrared read or a thermal camera should pick the spot first. Blind holes in January are how a small freeze turns into a drywall project.
The slow, boring thaw that works
Open the affected faucet before you apply any heat at all, both handles on a mixer, and leave it open the whole time. Melting ice needs somewhere to go, and an open tap keeps pressure from stacking up behind the plug. Then heat from the fixture end and work backward toward the ice, so meltwater runs out instead of getting trapped between two frozen sections. Heating the middle of a plug first is how people split pipe that would have survived.
Timing depends entirely on access. An exposed run under a sink might clear in twenty minutes. A plug inside an exterior wall can take three or four hours of a warm room and open cabinets, and it is not a sign you're doing it wrong. Slow is fine. Slow is better than fast.
- Open the affected faucet, hot and cold, and leave it open.
- Start at the fixture and move backward toward the suspected plug.
- Hair dryer, heat lamp, or a space heater at a safe distance. Hot wet towels rewrapped every few minutes also work.
- Warm the room and open cabinet and vanity doors so house heat reaches the wall cavity.
- Stay with it. Heat left running unattended on a pipe is how houses burn.
- When flow goes from nothing to a dribble, keep heating another few minutes and watch for drips.
What a thawing call costs, and when to make one
An accessible thaw is normally a service call plus an hour of labor, which along the Front Range usually means a couple hundred dollars into the mid hundreds. Add locating equipment, a finished wall or ceiling, or a run somebody has to reach on a ladder, and it climbs from there. After-hours work during a metro-wide cold snap is its own market, because the January night that freezes pipes in Aurora is freezing them in Arvada at the same hour and every truck is already committed.
Call sooner rather than later in four situations: you can't locate the ice, the line runs behind finished surfaces, a whole floor or the whole house has gone dry, or you've worked at it for forty-five minutes with no change in flow. A dry whole house usually means the buried service line, not an interior branch, and that's a different job entirely with different equipment. Our frozen main line page covers that one.
Season matters for scheduling. Thaw calls start on the Palmer Divide in late September, when Monument is already seeing hard frost and the plains still feel like summer. By the first week of October, Longmont and Firestone are in it too. And the wind towns get there early on the calendar and often on nights that look mild: a still fifteen-degree night in a sheltered yard is survivable, while the same fifteen degrees with a downslope gale across Superior or Louisville pulls heat out of a wall cavity three times faster.
The goal of a thaw isn't speed, it's not making things worse. Open the tap, warm gently from the fixture backward, stay in the room, and stop the moment you see water where water shouldn't be. Anything you can't see, can't reach, or can't identify is worth a phone call rather than a guess.
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Start a quoteFour things that must never touch a frozen pipe
An open flame, first and always. A propane or MAPP torch on a sealed frozen section can flash trapped water to steam with nowhere to vent, and it scorches framing you can't see behind the pipe. It also melts solder at every joint it passes. Torched pipes and burned houses have a long shared history in this trade, and no amount of care makes it a reasonable method.
Boiling water poured over a cold fitting, second. Thermal shock cracks brass and cast fittings, and the water you pour freezes on the floor into a skating rink at the exact moment you need footing. Third, a heat gun parked on PEX or CPVC. Both soften and deform well below the temperature that gun produces, and a deformed section becomes next winter's failure.
Fourth, combustion heat in a closed space. A kerosene salamander or a propane construction heater in a sealed crawlspace or a shut garage produces carbon monoxide with nowhere to go. If you're running any fuel-burning heater in a confined area and anyone starts feeling headachy, dizzy, or nauseated, get everyone outside and call the fire department. That is not a plumbing decision. If you smell gas at any point, leave the house first and call from outside.
The stopgap that actually helps costs nothing: a pencil-thin drip on the vulnerable run during a cold snap, cabinet doors open, and the room warm. It buys time. It is not a substitute for the insulation and air-sealing work that keeps the pipe from getting there next year.
Related work
More frozen pipes services
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Front Range cities we write for
Questions we actually get
Pipe Thawing Service: quick answers
How long should a frozen pipe take to thaw?
An exposed run under a sink often clears in fifteen to thirty minutes with a hair dryer. A plug inside an exterior wall can take several hours of a warm room and open cabinets, and that's normal. If flow hasn't changed at all after about forty-five minutes of direct heat, you're probably warming the wrong section of pipe.
Is a space heater safe to use on a frozen pipe?
It is, with rules. Keep it at least three feet from anything that burns, plug it straight into a wall outlet rather than an extension cord, put it on a hard level surface, and never leave the room while it runs. Warming the whole space is usually more effective than aiming it at one spot anyway.
The pipe thawed but now water is spraying. What first?
Shut the main off, then open the lowest faucets in the house to drain pressure out of the system. Kill power to any soaked area at the panel, not by reaching for a wet switch. Then photograph everything before you start moving water and belongings. Repair comes after the water stops, never before.
Ice in the wall and no flow?
Describe the dead fixture, the room, and your city, and we'll get it in front of someone who thaws lines for a living.
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