Gas furnaces create heat by burning natural gas or propane supplied directly to them by a gas line. You can hear them fire up with a whoosh – and you can often see flames through a small glass window inside the cover.
Electric furnaces create heat with resistance heating coils – they don’t burn any fuel, so they do not have a gas line. However, they do use 240-volt wiring instead of the 120V wiring used by a gas furnace.
There are distinct furnace parts, sounds and other clues that help you tell the difference between a gas furnace and an electric furnace.
This page answers that question – Is my furnace electric or gas?
We’ll give you tips for how to tell if your furnace is gas or electric. You can inspect your furnace and related parts using the information here to find the answer.
Gas Line vs No Gas Line
A gas furnace needs fuel, and that fuel is brought to the furnace through a gas line usually made of copper or steel.
The gas line enters the house from outside – usually through the wall in the basement, though it can be on a first or upper floor too.
ID Tip: The gas line has a shut-off valve in it that is usually within a few feet of the furnace or inside the cover of the furnace.
Electric furnaces do not have a gas line.
Gas Regulator and Gas Meter
These are two other parts found with a gas furnace, though they are not directly on the furnace.
A natural gas furnace has both. A propane furnace only has a regulator.
Both parts are often outside near where the gas line enters your home. However, in some cases, the regulator is indoors near the furnace.
ID Tip: Go to the location inside your home that corresponds to where the gas meter or regulator is placed.
Find, if possible, where the gas line enters the house. From there, follow where it leads.
If it leads to the furnace, you have a gas furnace.
Look Inside your Furnace
Most gas and electric furnaces have a cover panel held on by clips or a couple of fasteners. It should be easy to remove.
While you might not be able to see “everything” inside the furnace, here are a few things to look for.
Gas furnace – Interior gas furnace parts include:
A gas line running into the interior of the furnace.
A gas valve assembly connected to the gas line
Burners that fire when the furnace is creating heat. Most gas furnaces have a small glass port, roughly 1.5” across, through which you can see the blue flame of the burners. You might also be able to see a device called a heat exchanger, though most are deep inside the furnace and require the removal of a second panel to get to.
These parts are all unique to a gas furnace, so they answer whether your furnace is gas or electric.
Electric furnace – Interior furnace parts include:
A series of 3-6 elements connected by thick wiring and sensors on the exterior.
If you remove the fasteners on any of these elements and gently pull it out, the interior side will show an electric coil like something you might find in an electric space heater.
Check your Electrical Panel – 120V vs 240V
Both furnace types require electricity. The difference between a gas furnace and electric furnace is that the electric furnace uses electricity to create heat, so it needs more power.
A gas furnace uses electricity mainly to run the inducer and blower motors, so it needs less power.
How many circuit breakers does an electric furnace have? A gas furnace?
ID Tip: Look inside the electrical panel or circuit breaker box.
Find the breaker or breakers labeled “Furnace.”
Is there just one breaker – usually a 15 or 20 (stamped on the breaker) amp? That’s a breaker for a gas furnace, since they require only a single breaker.
Are there two breakers, usually stamped 20 for 20 amps? Those are almost certainly breakers for an electric furnace.
Note that the two breakers are connected by a single bar. You can turn them both on or off with one flip of the switch.
Listen to Your Furnace – Whoosh vs Buzz
You can also tell the difference between an electric furnace and a gas furnace by listening to it start up.
Turn up the thermostat setting by a few degrees to ensure the furnace starts.
What does a gas furnace sound like?
The first noise you’ll hear is a light humming noise. That’s the draft inducer motor starting.
The next noise you’ll hear is a “whoosh” as the gas valve opens, gas flows into the burners, and they ignite with a whoosh.
The third noise will be the blower coming on 15-45 seconds after the burners ignite.
What does an electric furnace sound like?
The first sound you might hear is a slight buzzing noise. If you’ve ever used a space heater, you’ll remember that noise from when the electric coils heat up.
You might not be able to hear the coils heat up – but you won’t hear an inducer motor or the tell-tale whoosh of gas igniting either.
Finally, the furnace blower motor will come on.
ID Tip: If the blower is the only sound you hear when the furnace starts, it is an electric furnace.
Do You Have a Propane Tank Outside?
This is a definite clue that you might have a propane gas furnace vs an electric furnace.
A propane tank is a large, steel tank, usually longer than it is tall, but not always. The ends are typically rounded. It will have a cap on top with a meter beneath it.
Yes, it’s possible that your furnace is electric but you use propane for other appliances like the water heater or the range.
That’s why it is useful to follow the gas line inside your home to see where it leads.
Are You Billed for Gas?
Find a paper copy of your utility or energy provider statement or log into your online account.
Does it show that you are billed for electricity only? Then, your furnace is electric. If it shows that you are billed for gas too, then you might have a gas furnace.
ID Tip: Gas is billed in cubic feet. Electricity is billed in kilowatt hours or kWh.