Burning questions

How many watts does an electric furnace use? It’s a bottomless pit

Using a furnace to keep your home warm during the colder months makes up over half of your energy bill. How many watts does an electric furnace use and how to bring the running costs down? Find out in our article.

Electric furnace resembles a hair dryer, in a way

Electric furnace diagram

An electric furnace keeps your home cozy using the power of electricity. In essence, an electric furnace works similarly to a hair dryer, using electricity to heat elements and then transferring that heat to air to keep you comfortable.

It starts with the thermostat, the brain of your heating system. When the temperature dips below your desired setting, the thermostat sends a signal to the furnace, saying, “Time to heat things up!” Upon receiving the signal, electricity flows through the furnace’s heating elements. As electricity passes through them, they resist the flow and heat up.

Then, a blower fan inside the furnace kicks on, drawing in cool air from your home. This air is then directed over the hot heating elements. As it passes over them, it absorbs their heat and is now ready to be distributed throughout your house. The heated air is then pushed by the blower fan into the ductwork, carrying it to each room, and warming your entire living space.

The thermostat continuously monitors the temperature. Once the desired temperature is reached, it signals the furnace to shut down, preventing overheating. The furnace will then turn on again when the temperature drops, maintaining a comfortable warmth in your home.

Furnace can devour half of your energy bill

The wattage of an electric furnace ranges somewhere between 10,000 watts and 50,000 watts, depending on the model. If you are living in a cold climate with harsh winters, own a large house and prefer warmer temperatures, your furnace will tend to the top of the scale. 

Since electric furnaces run only when the thermostat tells them to, they actually consume 50% less power. If you have a 20kW furnace, it consumes somewhere around 10kW per hour. If you turn it on for two hours a day, in reality it will run for one and use half as much energy.

Consumption per 2 hours = 20 kW × 2 h / 2 = 20 kWh

Despite that, we would reach 600kWh in a month of daily use. Considering the average American household draws roughly 900kWh of energy per month, electricity costs would make up over half of the electric bill.

Let’s estimate the cost of running your electric furnace. Multiply the consumption per day by your electricity rate, say, $0.20 per kWh:

Cost per day = (20 kWh × 2 hours / 2) × $0.20/kWh = $4

This will make $120 in a month, which would make over $350 for an entire winter. Fortunately, there are also a lot of ways to make it lower.

5 tips for using electric furnace efficiently

Feeling like your furnace operates more like a bottomless pit than a heating system? Here are five workable tips to enjoy a cozy home without breaking the bank.

Tip #1: Adjust your thermostat

Lower your thermostat by 1-2 degrees when you’re at home and awake. You can go even further by 5-7 degrees when sleeping or away from home. Every degree you lower the temperature can save you on your heating costs. A programmable thermostat will automatically adjust temperatures throughout the day and night, ensuring efficient heating even when you’re not at home.

Tip #2: Maintain your furnace

Schedule annual checkups for your furnace to ensure optimal performance and efficiency. A well-maintained furnace operates smoothly, minimizing energy waste. Regularly changing dirty air filters allows your furnace to breathe easier and work more efficiently, reducing energy consumption.

Tip #3: Improve home insulation

Sealing gaps around windows and doors prevents drafts and cold air from entering, reducing the workload on your furnace. Ensure your attic and basement are properly insulated to prevent heat loss from these areas, saving energy and lowering heating costs.

Tip #4: Try alternative heating strategies

Wear warm clothes and layer up to feel comfortable at slightly cooler temperatures, reducing reliance on the furnace. Consider using space heaters in specific rooms you’re occupying instead of heating the entire house, but ensure proper ventilation and avoid leaving them unattended.

Tip #5: Install a solar system

With solar panels, you won’t have to choose between a warm home and your electric bill. A home PV system generates electricity for all of your home appliances so that you don’t have to buy it from the grid.

Running an electric furnace on solar power solely is too hard. To start a 20kW electric furnace, you would have to build a 25kW solar system if we take into consideration power losses and inefficiencies of equipment. A solar system doesn’t have to match the electric furnace power rating though — you can always draw extra electricity from the grid.

17 cents

average cost of a kilowatt-hour in the US in 2024

Still, solar panels are going to at least alleviate the burden of high electric bills. A 7-kilowatt solar system — the most common size in the US — produces about 30 kilowatt-hours of usable alternating current per day in California. With the average cost per kilowatt-hour in Cali at about 19 cents, a PV system saves you about $150-$170 per month.

The difference between your solar system’s performance in July and January can be as much as 50%. In winter, a solar system can help run the furnace or a space heater but in summer it takes on the air conditioning unit — another big threat for your electric bill. Learn how much energy an AC unit consumes in our article. If you’re wondering how else you can save money on electricity, check out our article “How to make home energy efficient, save money and help the planet”.

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Years of experience in translation and a love of nature help Julia find the right words to encourage going solar. She joined the team in 2023 and is happy to make her contribution to a greener future.

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