Gas furnaces are one of the most popular types of central heating systems. According to the U.S. Energy Information Administration (EIA), nearly half of all homes in the United States rely on natural gas as their primary heating fuel. In comparison, only 36% of homes use electricity as their primary heating fuel.
Gas furnaces generate heat by burning natural gas in a combustion chamber. As they burn natural gas, they produce hot combustion gases that travel through a heat exchanger. The heat exchanger will then transfer some of this heat to the air moving over it, thus creating hot air. While they run on natural gas, however, gas furnaces still need electricity.
One of the reasons gas furnaces still need electricity is to power the electronic ignition. In the past, gas furnaces used pilot lights. A pilot light is a small flame that ignites the natural gas within the furnace’s combustion chamber. But pilot lights have since been replaced with electronic ignitions.
Electronic ignitions are starters powered by electricity. They consist of a conductive metal probe. As electricity travels through the probe, it will heat up. Upon reaching an appropriate temperature, the probe will ignite the natural gas.
The blower is also powered by electricity. Even if you have an old gas furnace with a pilot light, it won’t be able to warm your home unless it has electricity. The blower consists of a wheel and motor, the latter of which requires electricity.
If there’s a power outage in your home, the blower won’t be able to push air into the ductwork. Without electricity, the blower motor won’t spin, so neither your gas furnace nor your air conditioning system will work.
Of course, you may not be able to adjust the thermostat to turn on a gas furnace if the power goes out as well. Thermostats are powered by electricity. Many of them rely solely on external electricity. When the power goes out, they’ll turn off.
With that said, there are some thermostats that feature backup power in the form of batteries. They are designed to automatically switch over to the batteries in the event of a power outage.
Many homeowners are surprised to discover that they can’t use their gas furnace during a power outage. Gas furnaces may run on natural gas, but they still require electricity. They use electricity for the electronic ignition, blower motor and thermostat.