A furnace that stops working in January is one of the more stressful things that can happen to a Pittsburgh homeowner. Here is a calm, step-by-step approach for the first hour — and clear guidance on when to stop troubleshooting and call for emergency service.

First: is it safe?

If you smell gas, leave the house immediately, do not operate any switches or appliances, and call your gas utility from outside or from a neighbor's phone. Do not re-enter until the utility has cleared the building. If you have a carbon monoxide detector alarming, treat it the same way — evacuate and call 911.

Basic checks before calling for service

If there is no gas smell and no CO alarm, check the thermostat (set to Heat, set point above room temperature, fresh batteries), the furnace power switch (should be On), and the circuit breaker. Check the air filter — a severely clogged filter can cause the furnace to shut down on its high-limit safety. If the filter is clogged, replace it and wait 30 minutes before trying to restart.

Attempting a restart

Some furnaces have a reset button on the burner assembly — a red or yellow button that can be pressed once to attempt a restart after a safety shutdown. Press it once. If the furnace fires and runs normally, monitor it for the next few hours. If it shuts down again, do not press reset a second time — repeated resets can flood the heat exchanger with unburned gas, which is a safety hazard.

Keeping the house safe while you wait

If the furnace cannot be restarted and you are waiting for a technician, open cabinet doors under sinks to protect pipes, and use electric space heaters in occupied rooms if you have them. Do not use gas ranges, ovens, or outdoor grills for heat — these produce carbon monoxide. If temperatures inside drop below 55°F, consider staying with a neighbor or family member until the furnace is repaired.

Heirloom Mechanical is available 24/7 for emergency heating service in the Pittsburgh area. Call 412-889-6800 — we will tell you honestly what is wrong and what it will cost to fix it.