What to Do If Your Heater Won’t Turn On After a Storm in St. Louis

If your heater won’t turn on after a storm, start by checking that it has power, the circuit breaker hasn’t tripped, the thermostat is set correctly and powered, the fuel (gas or oil) is flowing, safety switches haven’t shut it down, and the pilot light or electronic ignition is working. If you still can’t get it to fire up, contact a qualified technician.

 

Initial Safety and Power Checks

 

Before touching anything, turn off the heater at its main switch or disconnect it to avoid shock. Whether you’re in St. Louis or Nashville, storms can knock out power to your furnace.

• Locate your home’s electrical panel and check for a tripped breaker labeled “furnace,” “heater,” or “HVAC.” If it’s in the middle position or off, flip it fully off, then back on.
• Find the furnace switch—often a light-switch style on or near the unit—and ensure it’s in the ON position.
• If your heater uses a fuse instead of a breaker, inspect it for a blown fuse and replace with the same amperage rating if needed.

 

Thermostat and Control Inspection

 

The thermostat is your command center. If it’s not calling for heat, the furnace won’t start.

• Set the thermostat to HEAT mode and raise the temperature at least five degrees above room temperature. Listen for a click—this tells you it’s sending a signal.
• Replace thermostat batteries if it’s battery-powered; weak batteries can prevent the heat call.
• Make sure the thermostat display is on. If it’s blank, power may be out to that circuit.
• Check wiring connections behind the thermostat cover. Loose or corroded wires can interrupt the heat signal.

 

Fuel Supply and Ignition System

 

Your heater needs fuel and a way to ignite it.

• Gas Furnaces: Ensure the gas valve at the furnace is open (parallel to the gas line). If you smell gas strongly, evacuate and call the fire department.
• Pilot Light (Older Models): Look through the sight glass. If the pilot is out, follow the manufacturer’s steps to relight it—usually turning a knob to IGNITE or PILOT and holding a button while using a long lighter.
• Electronic Ignition (Newer Models): These use a spark or hot surface igniter. If you hear clicking but no ignition, the igniter may be faulty and require replacement.

 

Airflow and Filter Maintenance

 

Restricted airflow can trigger safety limits that shut down heating systems.

• Locate the air filter—usually in the blower compartment or return-air vent—and inspect it. If it’s dirty or clogged, replace it with the correct size and type.
• Ensure all vents and registers throughout your home are open and free of furniture or debris.
• Check the return-air grille for blockages like curtains or rugs.

 

Additional Safety Switches and Sensors

 

Furnaces have built-in safety devices that can trip during power surges or blocked airflow.

• High-Limit Switch: If the furnace overheats, this switch cuts power. After filter cleaning, reset it by finding the red or yellow button on the blower housing and pressing it once.
• Float Switch (Condensate Safety): High-efficiency units drain water. If the drain line clogs, the float switch opens and shuts the system. Clear the condensate line with a wet/dry vacuum.
• Pressure Switch: Ensures proper venting. A blocked flue or failed inducer motor can keep this switch open. Inspect for vent obstructions and listen for the inducer fan motor running.

 

When to Call a Professional

 

If you’ve checked power, thermostat settings, fuel supply, filters, and safety switches and your heater still won’t start, it’s time to call a certified HVAC technician. They can safely:

• Diagnose electrical faults, faulty igniters, or control board issues.
• Test gas pressure and combustion to ensure safe operation.
• Inspect heat exchangers for cracks or corrosion.
• Perform preventive maintenance to avoid future breakdowns.

A qualified technician carries the right tools and parts, follows safety codes, and restores reliable heat so you stay warm and safe after any storm.