Most furnaces are gas-powered. That is because it costs less to run gas furnaces over electric ones in most areas in the US. That is however not to say that gas furnaces are more efficient that electric furnaces, and there are areas where electric furnaces are cheaper to run.
Telling whether a gas is electric or gas is easy if you know where to look. There are however many homeowners who can’t tell if they have a gas or electric furnace.
So, how can you tell if you have a natural gas or electric furnace?
Start by turning up the heat then head over to the furnace. If you can see a blue flame inside the furnace through a small glass window then you have a gas furnaces. Also, the presence of an exhaust vent, gas line (usually black iron pipe) and noises from the burner are signs that you have a gas furnace.
In most cases, the easiest way to tell if you have a gas furnace is to read the label on the furnaces. If there is no label, just know that a gas furnace will a have a small glass window, gas line and exhaust vent and will also make some noises. Electric furnaces have no glass window, gas line, exhaust vent and do not make any noise.
Another thing you may want to first establish is whether you indeed have a forced air heating system. It is not unusual to find radiators and baseboard heaters in some homes, especially in old houses.
Also, find out if you have a furnace or an air handler. Furnaces and air handlers look almost the same and some homeowners may have a problem telling them apart. So, how do you know what you have?
If you have a central air conditioner, it will be paired up with a furnace. On the other hand, if you have a heat pump, it will be paired with an air handler.
Most air handlers heat the house through electric resistance heating but some are hybrid (electricity and gas). Now, if you are not sure if you have a heat pump or air conditioner, check out this post.
Do You Have a Forced Air Heating System?
As I have mentioned, even before you check out if you have a gas or electric furnace, you should first ensure that you indeed have a forced air heating system.
If you house has vents (return and supply) and ductwork, you indeed have a forced air heating system. The furnaces blower pulls air from the house through the return air ducts and after heating it forces it back to the house through the supply air ducts.
On the other hand, if you see a baseboard heater, radiant heat, boiler or even mini-splits, you do not have a forced air heating system.
Forced air heating can be gas or electric. The only difference however is that in a gas furnace, the burner produces heat after burning natural gas, where the heat is then absorbed by the air at the heat exchanger.
With an electric furnace, current flows through a heating element which makes it hot and as air moves across the element it absorbs heat from it.
Heating inside the house is controlled by a thermostat which is centrally located (unless you have a zoned HVAC system which has several thermostats).
With a gas furnace, when the thermostat calls for heating, an electronic ignition starts the burner component inside the combustion chamber. The flame from the burner component then heat a metal heat exchanger.
The heat generated circulates through the looped tubes of the heat exchanger. As the air moves across the tubes, it absorbs heat from the heat exchanger and that is how it gets heated.
An electric furnace does not have a burner and all it does is send a current through the heating element (coils) which them becomes red hot (in accordance with the amount of current being send to them).
After air has absorbed heat from the furnace, the blower forces it through the ductwork and out into the house through the supply vents.
How to Tell if You Have a Gas or Electric Furnace
The following are the different ways to tell if you have a gas or electric furnace for your forced air heating system. Start by turning up the heat on the thermostat (you need to see if you can see gas burner’s flame).
1. Read the Label
This could actually be the fastest or easiest thing you can do. Furnaces have a label or nameplate on them where you can get lots of information about it including model number.
Most furnaces will have the type (gas or electric) clearly indicated on the nameplate/label. Even if the label fails to identify what type of furnace you have, you can still use the model number to know what type of furnace it is by performing a quick search on the internet.
Another thing you can do is check the furnace user manual if you still have it. The manual will clearly state if it is a gas or electric furnace.
2. Look for a Blue Flame
Gas furnaces will have a small glass window through which you can see a blue flame inside the furnace (when it is on). On the other hand, electric furnaces do not have a flame and neither do they have a glass window.
If you therefore see a blue flame through the window, you clearly have a gas furnace. Otherwise it is an electric furnace.
3. Is there a Gas Line to the Furnace?
As you already know, a gas furnace would need to be connected to your house’s gas supply. That would be in the form of a black iron pipe (which is the best and most used pipe for connecting gas to appliances).
You can however in some cases have a copper pipe or even a yellow plastic hose. You just need to trace the pipe and see if it is connected to the gas lines to your house.
4. Can You See an Exhaust Vent?
Just like gas water heaters, electric furnaces will have an exhaust vent to remove the burnt gas fumes to the outside. Check if you can see an exhaust vent installed to serve the furnace.
If there is indeed an exhaust vent, you surely have a gas furnace. Absence of an exhaust furnace is a sign that you have an electric furnace.
5. Can You Hear Some Noises?
Gas furnaces will make some noises when running. That is the noise caused by the burning of gas (just like in your stove) and can be clearly heard when you are close to the furnace.
On the other hand, electric furnaces running quietly. You can therefore use the noise made by the furnace to identify if it is gas or electric.
Summary
A gas furnace will have a blue flame seen through a small glass window, it will have an exhaust vent, gas pipe and you can hear some noises as the flame is burning. On the other hand, an electric furnace will be quiet, without a flame and glass window and will also not have an exhaust vent or gas pipe.