What is forced-air heating? Your guide to maintenance and energy efficiency

Key points

• Forced-air heating uses a furnace to heat air and blower motors to distribute the warmth through ducts.

• Energy Star-rated furnaces are up to 11% more efficient and can save you $30 to $80 annually on utility bills.

• Forced-air heating ductwork can be used for cooling if you install a central AC compressor.

Forced-air heating is the most popular type of heating in the U.S. sold by some of the best furnace brands out there. Upgrading to a high-efficiency hot air system can improve heating efficiency by up to 11%, according to the U.S. Department of Energy (DOE). 

Forced-air heating — commonly called a forced hot air (FHA) system — uses a furnace to heat and distribute air throughout the home. This type of heater is more efficient than boiler systems, which heat and distribute water, reaching efficiencies of up to 98.5% as opposed to the maximum of 90% you can get from a boiler.

According to Energy Star, the average annual home heating bill is around $600. If you have an 8.5% bump in efficiency from switching to a forced-air home heating system, you could save an average of $50 annually. Over the potential 30-year lifespan of these systems, that’s a total potential savings of $1,500.

Ray Snesrud, founder and CEO of Water Heaters Now, a plumbing and HVAC company in Burnsville, Minnesota agrees: “FHA systems are much more efficient than electric baseboard heating but not quite as efficient when compared to radiant heating systems.”

Forced-air heating systems aren’t right for everyone because they can be noisy, depending on the equipment location in the home, and they come with added maintenance for ductwork. 

Before you reach out to an HVAC system specialist for an estimate, understand the perks of an FHA and how it works to see if it’s suitable for your home.

How does a forced-air heating system work?

A forced-air heating system uses a central heating system called a furnace to create heat. The furnace heats the air by using natural gas as a fuel source in around 57% of U.S. homes, as estimated by the DOE.

An air handler connected to the furnace uses a blower motor to pull heated air from the heating chamber and push it through ductwork that runs through the home. The ductwork is hidden behind walls, ceilings and floors, and it delivers air through supply vents to heat the living area.

The same ductwork that your heated air travels through in the winter can carry cooled air in the summer, but you’ll need a central air conditioning system in addition to your furnace.

The blower motor then pulls air from the home in through the return vents. It is delivered back to the furnace for heating as necessary. Some forced-air heating systems are also equipped with mechanical ventilation systems, which pull fresh air from the outside through the vents for heating. These systems use separate vents and blower motors to introduce fresh air into the air ducts.

Is forced-air heating energy-efficient?

Forced-air heating can reach up to 98.5% efficiency, making the system extremely efficient. These ratings refer to the amount of energy lost from burned fuel — gas, oil or electric — to the air surrounding the furnace as it functions. The rating is called AFUE, which stands for annual fuel utilization efficiency. It measures the amount of energy from the fuel source that gets turned into heat. The higher the AFUE rating, the more efficient the heater.

The Energy Star qualifications for furnaces are 5% to 10% higher than for boilers — 90% to 95% as opposed to 85% — because furnaces can reach higher levels of efficiency.

Is forced-air heating gas, electric or oil?

Forced-air heaters can use gas, electricity or oil as a fuel source. The fuel source that’s best for you depends on the availability of natural gas connections in your area and the local price of oil and electricity.

Electric furnaces are technically the most efficient, potentially reaching 100% AFUE. However, electricity is typically produced using natural gas or oil at a power plant with just 30% efficiency. Unless you produce your own electricity via solar panels, heating costs are likely to be higher with an electric furnace.

Gas furnaces and oil furnaces burn their respective fossil fuels to produce heat, which then heats the air in the main heating chamber inside the furnace before it moves through the home.

Some modern furnaces are hybrids that use both gas and electricity. Hybrid systems will switch to electric as a fuel source to conserve energy in mild weather. Gas-fired furnaces heat faster than electric furnaces, making gas the preferred fuel source in extremely cold weather. “Electricity is a less powerful source for heat than gas by a long shot,” Snesrud said. “In cooler climates, a gas FHA [system] is the only economical option.”

Can forced-air heating be used for cooling, too?

Forced-air heating systems can only be used for heating your home, as this system cannot cool air. However, FHA systems make use of ductwork that runs through your home to deliver conditioned air. You can install a central cooling system that uses the same ducts to cool your home. This gives you year-round temperature control.

Based on prices from Lowe’s, a central AC condenser will cost between $1,100 and $5,600, depending on the brand, size and seasonal energy efficiency ratio (SEER). This price does not include installation labor.

Combining your heating system with an AC can save you money on installing ductwork. If you had a boiler and hot water heating system that would require new ductwork to be installed, you’d be paying for the AC system, duct installation and the labor for both.

What are the pros and cons of forced-air heating?

The high efficiency of forced-air heating systems and the option to introduce fresh outdoor air into the home using built-in ventilation systems help make forced-air heating a popular option in the U.S. Boiler systems don’t come with built-in ventilation, which means the only way to get fresh air inside is to open windows or doors. 

However, there are drawbacks, including needing access to natural gas lines in your area. 

Here are some benefits and downsides to forced-air heating.

Forced-air heating pros

• 8.5% to 9% more efficient than boilers
• Potential lifetime savings of $1,500 over boilers
• Can introduce outdoor air into the home rather than recirculating indoor air
• You can use ductwork alongside central air conditioning to cool the home 
• No baseboards or radiators to take up living space, unlike hot water and steam boilers

Forced-air heating cons

• Blower fan creates noise alongside airflow, sometimes hitting 20 decibels at the source — the volume of a ticking watch
• Cannot cool home without additional equipment
• You may need occasional duct cleaning to remove allergens and contaminants
• Between 20% and 30% of the conditioned air in most ducts is lost to leaks, which leads to higher energy bills

How much maintenance do forced-air heating systems require?

Forced-air heating systems require about the same amount of maintenance as other heating systems. You should expect to carry out routine DIY maintenance, including changing air filters to prevent debris build-up and excess strain on your blower motors. Just keeping your air filters clean can reduce energy consumption by up to 15%, the DOE reports.

Homeowners should also have a tune-up completed regularly to ensure moving parts are lubricated and any minimal wear is addressed before it turns into a problem.

“Changing the filter once a month for the 1-inch-wide models [of air filters] is good, whereas the 4-inch models need to be only changed twice a year,” Snesrud said. “For preventative maintenance, a biannual checkup should be done by a professional. Often small adjustments in pressure settings can prevent a major repair bill.”

What’s next?

Modern furnaces hit AFUE ratings of up to 100% for electric models and 98.5% for gas-fired models, which translates to utility bill savings of up to $1,329, according to the DOE. Upgrading to an Energy Star-rated furnace is a good idea if you’re in the market for a new heater.

You can also get the most value out of your existing ductwork by coupling your forced-air heater with a central AC to use in the summer.

If you know your existing system has more life and you’re not quite ready to upgrade, consider hiring a local HVAC professional to carry out routine maintenance. Regular tune-ups and inspections can extend the life of your system and help avoid repair costs.

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