What to do when your Gas Furnace or Boiler Doesn’t Start?


It’s the first cold snap of the season and the last thing you want to be dealing with is a heater not working. We have a few things to check to see if you can resolve the issue yourself before calling for an emergency service appointment. If after you go through these few tips and you’re still having issues with your heater, give the Cool Crew a call. We’ll get an appointment scheduled with one of our experienced technicians to evaluate your system and work to get it back up and functional.

Check the thermostat.

Make sure the temperature is set above the current room temperature and the system is set to HEAT position. Your thermostat may have two options for the fan setting. The Fan ON option allows you to run the system blower continuously. The AUTO setting will only run the blower when the system is heating. Try to get the heater to turn on by raising the thermostat to the highest temperature setting than the room temperature.

Did you lose electricity? Did a breaker trip?

If you lost electricity recently, check to see if a breaker tripped. Flip the switch on the breaker back on and see if your furnace or boiler starts. If your breaker continues to trip, please call us to schedule an appointment.

Also check that the electrical switch on the furnace is in the ON position. If your system has recently been serviced, this switch may have been accidently left in the OFF position.

When was the last time you changed the filter on your system?

A dirty filter makes your system work harder to move warm air efficiently throughout your home. Dirt can also accumulate on coils resulting in further restricting airflow. When your system must work harder, parts may wear out quicker and need to be replaced sooner. A clogged filter can cause a furnace to shut down. Replacing a dirty filter can lower your furnace’s energy consumption by as much as 15 percent.

Did your pilot light go out?

Older gas furnaces use a standing pilot light that may have been extinguished. It could be a combination of things that caused this issue. If your furnace clicks on, but doesn’t fire up, there most likely is a pilot light or ignition sensor issue. We recommend calling for a service appointment and not cleaning the sensor yourself. Newer systems use an electric intermittent pilot ignition that receives a signal from the thermostat and should be inspected by a professional.

Is the service door on your furnace or boiler closed?

Check to see if the service door on your furnace is properly shut. If you recently changed your filter or had service, the door may have been left open or closed incorrectly. Most furnaces have a safety sensor that prevents the furnace from running if there is an issue with a door.

When was your heating system last serviced?

Finally, be sure to schedule routine maintenance yearly to keep your heating system operating at optimal levels. Routine maintenance also can catch small problems before they turn into a major issue. Routine maintenance also boosts efficiency which drives down heating costs and can extend the life of your heating system.

Need to schedule a service appointment? Contact the Cool Crew today!