What Should I Do if My Furnace Won't Ignite?

Gas furnaces have proven to be one of the most dependable means of warming up your home -- but that doesn’t mean they’re invincible. Gas furnaces, like every household appliance, can go kaput when you need them the most. One of the most common problems with furnaces is that they won’t ignite. This can be very inconvenient especially during the colder seasons of autumn and winter.

When your gas furnace won’t ignite, the best solution would be to give your reliable HVAC specialist a call. The service will cost you some money, but it’s a safer alternative than fixing your furnace ignition on your own. If you end up destroying your furnace, you might even find yourself having to buy an entirely new unit.

Why isn’t my furnace igniting, and what should I do?

Check the thermostat

In most cases, homeowners just forget to set their thermostat properly. Make sure that your thermostat is actually set to heat your home. If this doesn’t address the issue, turn the fan switch to “on” and see if the furnace starts to blow air. If you’re using a programmable thermostat, check the display for error codes.

Check the air filter

If your furnace’s filter hasn’t been cleaned and changed in years, this means that your vents and registers are blocked. Dirty air filters can obstruct proper airflow. Be sure that your furnace filter is free from dirt, dust, and other debris. If necessary, replace it with a brand-new filter. A professional HVAC technician can help determine the proper filter for your type of furnace.

Check the gas supply

Is gas even getting to your furnace? When your furnace fails to ignite, the problem might be with the gas line. If you’re using a city gas line, there’s not much you can do but wait for the professionals. Checking the natural gas line by yourself is dangerous. But if you’re using a propane gas tank, you simply need to read the valve and check the pressure gauge. If it reads 24 or below, call your local gas company to fill up your tank.

Check the condensate pan

A high-efficiency furnace can experience acidic condensation. This means that the collection pan fills up with liquid, triggering the float switch which shuts off the furnace. This automatic feature prevents water from damaging your unit. Check the condensate pan often to see if it is full, then empty it into a sink, and unclog the condensate drain. If you’re not sure how to safely do this, call an HVAC professional.

Check the pilot light

Most modern furnaces use an electronic ignition system, but if you’re using an older heater, it most likely has a pilot light or an ignition sensor. If it has blown out, your furnace won’t ignite. Fixing it is fairly easy -- all you must do is remove the ignition sensor, clean it, and put it back where it came from. Again, if you can’t do this safely, call an HVAC professional.

When should I call an HVAC technician?

Avoid troubleshooting by yourself unless you’re confident in what you’re doing. Furnaces are sensitive and complicated machines that often require professional servicing. If none of the abovementioned steps ignite your furnace, you should consider calling a trained HVAC specialist. They have the tools and experience to determine most furnace problems so that you don’t have to layer on sweaters just to stay warm.