4 Reasons Why Your Furnace Won’t Light

Furnace light.

Why Won’t My Furnace Light?

Most homes, old and new, have a gas furnace installed. Depending on when it was installed, a furnace can last up to 20 years with proper care. However, during that time you may experience random hiccups with your furnace like the furnace light going out. In some cases, a furnace won’t light because there’s no gas going to it.

Here are a few other reasons why your furnace may not ignite.

1. Broken Flame Sensor

A broken flame sensor could be the reason your furnace won’t light. Flame sensors are what turn off the gas burners in order to avoid gas buildup. If a flame sensor is broken, it will prevent the gas burners from igniting.


To fix this problem, you can replace the flame sensor or contact your local HVAC technician to safely replace it for you.

2. Broken Thermostat

If you turn your heater on and notice that no matter how high you set it to, your home just won’t warm up then the problem could be your thermostat. Normally, when your heater ignites after turning up the temperature on the thermostat, you may hear the flame ignite on the burner.

However, if you turn on your thermostat and don’t hear the flame ignite or feel the heat, you should contact an HVAC technician to inspect your heater and the thermostat for issues.

3. Dirty Gas Burners

When gas burners get dirty, they can’t carry enough oxygen to ignite. The best way to find if this is the problem is by hiring a technician to safely and properly clean the burners.

4. The High Limit Switch is Open

If the safety switch is open, then the gas burner on your heater won’t turn on. The switch’s job is to turn off the furnace if it gets too hot or if the air filter is clogged because air can’t circulate to keep it cool.

Contact A. Fagundes Plumbing & Heating Inc. to Inspect Your Furnace

When you run into problems with your furnace, rely on a professional HVAC technician to run tests, inspect, repair, and maintain it. HVAC professionals have the right equipment and knowledge to fix any issues you may have related to your HVAC system as a whole. Give us a call when you need us at (978) 350-5522 to schedule your appointment!