How to Winterize a Vacant Unit or Rental in Boston So You Do Not Get the January Call

Empty units freeze. A vacant condo with the heat off, a rental between tenants, a summer place on the South Shore closed for the season. Here is the checklist that keeps them dry until spring.

If the unit will stay heated

• Thermostat at 55 minimum. Lower than that and pipes on exterior walls are at risk in a deep freeze.
• Open cabinet doors under every sink so warm air reaches the supply lines.
• Put a smart thermostat or a Wi-Fi temperature sensor in the unit so you get an alert if the heat fails. A $40 sensor has saved us from more than one rebuild.
• Shut off the water at the unit valve anyway. Heat can fail; a closed valve cannot leak.
• Check it every week. Insurance policies often require inspection every 30 days or less on vacant property, and some void coverage after 60 days of vacancy without notice to the carrier.

If the unit will not be heated

1. Shut off the main water supply.
2. Open every faucet, flush every toilet, and drain the lines from the lowest point. Use compressed air if there is a drain-down valve.
3. Pour RV antifreeze (the pink kind, not automotive) into every toilet bowl and tank, and every sink, tub, and shower trap. Traps hold water and they freeze.
4. Drain the water heater, or leave it full and keep it on low if the room will stay above freezing.
5. Disconnect and drain the washing machine and dishwasher lines.
6. Unplug the refrigerator and prop the doors open.

Tell your insurance company

Most Massachusetts policies have a vacancy clause. If a unit is vacant more than 30 or 60 days and you have not told the carrier, a frozen pipe loss can be denied outright. A phone call to your agent, and a vacancy endorsement if they require it, protects the claim.

For property managers with several units

Put the winterization on a checklist with a date and a signature, and keep it with the unit file. When a carrier asks what was done, that checklist is the answer. We provide it as a service for owners with multiple vacant units, with photos of each shutoff and each drained fixture.

In the spring

Turn the water back on slowly, one fixture at a time, and watch for leaks at every joint. Pipes that survived the winter can still have hairline splits that only show under pressure.