Why East End and Fire Island Homes Freeze
A lot of seasonal housing in Southampton, East Hampton, Sag Harbor, Montauk, Westhampton, Shelter Island, Southold, and on Fire Island was built for summer and winterized later. That means plumbing in crawlspaces and on exterior walls, and heat added after the fact. Add wind off the ocean and bays, long stretches with nobody inside, and power that can drop for days after a nor'easter, and small failures go unnoticed until the thaw.
Fuel is the other East End factor. Large parts of the South Fork and North Fork have no natural gas main, and Fire Island has none at all, so most second homes run on oil, propane, or heat pumps. A tank that runs dry in January is one of the most common causes of a frozen house.
Heat On, Winterize, or Glycol?
| Factor | Keep Heat On | Full Winterize | Glycol Hybrid |
|---|---|---|---|
| Best for | Homes used some winter weekends | Summer-only homes, Fire Island cottages | Hot water heat, rarely visited |
| Heating pipes | Protected while heat runs | Drained | Glycol in the loop |
| Domestic water | Live (or partly isolated) | Drained, antifreeze in traps | Drained |
| Main risk | Fuel runs out, power or boiler fails | Missed low spot or trap | Glycol not tested or diluted |
| Winter cost | Fuel + monitoring | Shutdown + spring start-up | Glycol + some fuel |
If You're Leaving the Heat On
Service the boiler or furnace
Get it cleaned, tested, and combustion-checked before you leave, not at Thanksgiving when it fails.
Lock in fuel
Automatic oil or propane delivery, plus a tank monitor that reports the level to your phone.
Remote temperature alerts
A Wi-Fi thermostat or a separate low-temperature sensor that texts you, plus leak sensors under sinks, near the water heater, and at the boiler.
Know how the boiler gets its water
Before you close the main, find out whether it also feeds the boiler (see the FAQ below).
Plan for outages
Boilers and furnaces need electricity. East End and barrier-island outages can last days. A standby generator on the heating circuit is the real fix.
Someone with a key
A caretaker or house-watch service that checks inside, not just the driveway. Insurers often expect regular checks of a vacant home.
The boiler water-valve trap
Closing the main water valve is good advice for a vacant house, but on many Long Island homes it also cuts the boiler's automatic fill. If the heating loop then loses water through a small leak, the boiler's low water cutoff does its job and shuts the burner off, and the house freezes with the thermostat still calling for heat. Have your technician confirm where the boiler's fill comes from, and if needed add a dedicated valve so everything else can be shut while the boiler stays fed.
If You're Shutting It Down
A proper winterization drains every low point in the heating and plumbing, not just the obvious ones. That includes the boiler, baseboard and radiator loops, the water heater, outdoor showers and hose bibs, ice makers, and washer lines. Compressed air clears what gravity leaves, and non-toxic RV antifreeze goes into every trap and toilet.
The spring start-up matters just as much: refill slowly, purge air from the heating loop, check for split fittings before the water is fully on, and light and test the boiler or furnace before the first guests arrive.
Glycol for Hot Water Heating Systems
In a closed hot water system (baseboard, radiators, radiant floors), propylene glycol in the loop keeps the heating pipes from bursting if the heat fails. It needs the right concentration, an annual test, and proper backflow protection on the boiler fill. It protects only the heating loop, so domestic plumbing still needs its own plan. If your house has radiant floors, see our radiant heat service page.
Fire Island Specifics
Fire Island adds logistics to everything: winter ferry schedules thin out, freezes on the bay can stop service, and every part, tool, and fuel delivery has to be planned around the water. Book fall shutdowns and spring start-ups well ahead for Ocean Beach, Saltaire, Fair Harbor, Cherry Grove, Fire Island Pines, Davis Park, and the other communities. And if you keep a winter-use house there, keep a remote temperature alert and a local contact with a key.
Insurance: Read the Freezing Clause
Many homeowners policies exclude freeze damage in a vacant or unoccupied house unless you maintained heat or shut off and drained the water. Keep your service invoices, fuel delivery records, and thermostat or sensor logs. They're your proof of reasonable care if a pipe does let go.