Frozen pipes: the winter checklist for pre-war apartments

Every January we thaw and repair a few dozen frozen pipes, mostly in the same kinds of apartments: pre-war walk-ups with plumbing in an exterior wall and a heating system that was balanced for a building that no longer exists. Here is the checklist we hand out in November.

Before the first freeze

Find the pipes that run along outside walls, usually the kitchen sink and any bathroom on a corner. Open the cabinet doors under them on cold nights so room air reaches the pipe. If a radiator under a window has been cold for a winter or two, get it bled or balanced now; an unheated room is where the pipe in the wall freezes.

During a cold snap

Leave a faucet on the exterior wall dripping, a pencil-thin stream is enough. Keep the heat on when you travel, no lower than 55°F. If you go away for more than a weekend, shut the supply valve at the apartment and open the faucets to drain what you can.

If a pipe has frozen

Turn off the water at the shut-off. Open the faucet so melting water has somewhere to go. Warm the pipe slowly, a hair dryer, warm towels, never an open flame. If you see a split in the pipe or water anywhere it should not be, stop and call; that is the $349 thaw-and-repair on the board and it is cheaper at 9 AM than at 2 AM.

We also fit insulation on exposed runs and replace shut-off valves that no longer close, $249 for a new shut-off, and it is the most useful $249 in a pre-war building.