One Warm Room
Heat & Cold
Keeping one room habitable and the plumbing intact when the furnace has no power — and doing it without poisoning anyone.
The first surprise for most people is that a gas furnace stops working in a power outage. The fuel is still there; what is missing is the electricity for the blower, the igniter and the control board. Same for a propane boiler with a circulator pump, and same for a pellet stove, which is a gas appliance with an auger and a fan. Almost every modern heating system in an American house is an electrical appliance that happens to burn something.
The real threat is the plumbing, not the discomfort
A healthy adult in a sleeping bag can tolerate a 45°F house for days. Copper and PEX cannot. Water expands as it freezes, splits a line in an exterior wall or an unheated crawlspace, and then does its real damage when the heat comes back on and the split line starts pouring. That repair — plumbing plus drywall plus flooring plus whatever the water touched on the way down — routinely runs into thousands of dollars, which makes it the single most expensive failure in this entire section.
How fast a house cools depends on insulation, wind and starting temperature, but a rough rule for a reasonably insulated house in still air is a drop of about 1-2°F per hour with outdoor temperatures in the teens. That gives you somewhere between one and two days before interior pipes are at risk — long enough to act, short enough that the decision needs to be made before the outage, not during it.
Options for heat without the grid
| Source | Rough cost at the time of writing | Notes |
|---|---|---|
| Indoor-rated propane heater (Mr. Heater class) | $100-$200 | 4,000-18,000 BTU; needs an oxygen depletion sensor and cracked ventilation |
| Vented kerosene or propane wall heater (Dyna-Glo class) | $300-$800 plus install | Vents combustion outside; the safer permanent option |
| Wood stove | $2,500-$6,000 installed with chimney | Works with zero electricity; needs seasoned wood and annual chimney cleaning |
| Generator running the existing furnace | see Power & Backup | Blower is often 300-600 W running, 1,000-2,000 W at startup |
| Insulation, weatherstripping, thermal curtains | $100-$600 | Reduces the size of every other solution, permanently |
Note where the best value sits. A generator large enough to run a furnace blower solves the problem elegantly and costs more than a wood stove’s annual firewood for a decade. A $200 indoor-rated propane heater plus $300 of air sealing solves it adequately and buys you the ability to keep one room at 60°F on a 20 lb tank for a couple of days. Which is right depends on how often your area actually loses power for more than 24 hours in winter.
Safety: Carbon monoxide has no smell and no color, and it kills people every winter who were only trying to stay warm. Never run a generator, charcoal grill, camp stove or unvented kerosene heater inside a house, a garage or a porch. Use only heaters explicitly rated for indoor use, keep a window cracked, and put battery-backed CO alarms on every level and outside every sleeping area.
Protecting the pipes
- Know where your main shutoff is and make sure it turns. If you leave the house in a cold outage, shutting off and draining is the cheapest insurance there is.
- Open cabinet doors under sinks on exterior walls so room air reaches the supply lines.
- Let a faucet drip on the most vulnerable run. Moving water resists freezing and a dripping line relieves the pressure that actually splits pipes.
- Insulate the exposed runs now — crawlspace, garage, exterior walls, well head. Foam sleeve is a few dollars a length and it never needs a battery.
- Close off the rest of the house. Pick one room with the fewest exterior walls, hang blankets over doorways, and heat that. Heating 200 square feet is a different problem from heating 2,000.
Where this connects
If freezing forces you to drain the system, your stored water becomes the whole supply — see Water. Heating decisions also determine whether a generator needs to cover the furnace blower, which changes the sizing in Power & Backup. Hypothermia and carbon monoxide poisoning are covered in Health & Safety, the building envelope in The House, and how long you should plan to hold out in By Scenario. Working through the plan in sequence? Go back to Start Here.