Check the thermostat, furnace switch, and breaker only if there is no smell of gas, smoke, or other danger. If a carbon-monoxide alarm sounds, leave and call emergency services. Do not use an oven, grill, or outdoor heater indoors. Open cabinet doors below sinks on exterior walls, let faucets drip if appropriate, and know where the main water shutoff is. Keep children, older adults, and pets warm elsewhere if the outage will last. Call for emergency HVAC help and describe the fuel type, symptoms, and indoor temperature. A temporary space heater should sit on a hard surface with clear space around it and should plug directly into the wall.
What to ask next
The right next step depends on the system, the urgency, and the building. Keep the model number, symptoms, age, and any previous service notes nearby when you request an estimate. A professional should explain the diagnosis or sizing basis in plain language.
When to bring in a professional
Use the callback form to describe the issue, or review HVAC services to find the closest starting point. For urgent loss of heat, see what to do in a cold snap.