No heat right now: the complete 10-minute emergency checklist

Cold house, cold night. Run this exact order — it is arranged by how often each step is the answer, and every step is free.

1. Thermostat

Heat mode. Setpoint 5+ degrees above room temp. Fresh batteries. Screen alive.

2. Furnace switch

The light switch on or beside the furnace. On.

3. Breaker

Furnace breaker on; reset once if tripped.

4. Filter

If you cannot see light through it, swap it. Overheat shutdowns from clogged filters are the #1 no-heat cause in midwinter.

5. Blower door

Firmly seated. The door switch kills everything silently.

6. Gas

Valve handle parallel to pipe. Stove works? Then supply is fine.

7. Vents outside (high-efficiency)

Snow or ice blocking the PVC intake/exhaust is THE classic cold-snap failure. Clear both pipes.

8. Power-cycle

Furnace switch off, count 60 seconds, on. Clears many latched faults.

9. Read the blink code

Burners still not lighting? Watch the little window on the furnace for the flashing LED and count the pattern — then look it up on this site to know exactly what to tell the technician.

10. Space heaters + dripping taps

While you wait for the tech: heat the occupied room only, and on a hard-freeze night let faucets on exterior walls drip so pipes survive.

Safety line: Gas smell at any step: out of the house, utility emergency line, from outside. Below-freezing night with no fix in sight: burst pipes cost more than any emergency service call — do not toughing-it-out your plumbing into failure.

Is the furnace flashing a light?

If the burners will not light, the control board is almost certainly flashing a diagnostic code behind the little window. Count the flashes and look the code up by brand here — walking into the phone call knowing the code saves diagnostic time.