The Biggest Differences Between Boiler Radiators and Furnaces

By HomeAdvisor

Updated April 7, 2022

matteogirelli/iStock/Getty Images Plus via Getty Images

Reviewed by Jeff Botelho, Licensed Journeyman Plumber.
Written by HomeAdvisor.

The boiler versus furnace debate isn’t as straightforward as you might think. While they both warm the inside of your home, one runs on water and the other uses hot air. Other factors such as differing costs, ongoing maintenance and repair, and the type of home you own can help you decide which is right for you.

On This Page

  1. What’s the Difference Between Boiler Radiators and Furnaces?
  2. Boiler vs. Furnace: Which Is Better?
    1. Size and Appearance
    2. Cost
    3. Installation and DIY
    4. Energy Efficiency
    5. Maintenance
    6. Repair
  3. Which Is Best for Your Home?
    1. Which Is Best for Your Home in Cold Weather Climates?
    2. Which Is Best for Smaller Homes?
    3. Which is Best for Older Homes?
  4. Boiler vs. Furnace vs. Heat Pump
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What’s the Difference Between Boiler Radiators and Furnaces?

Both units keep your house warm during the cold winter months. The major difference between a boiler and a furnace is that a boiler uses gas, oil, or electricity to generate steam or boiling water, while a furnace uses hot air.

As its name implies, a boiler distributes heat generated from boiled water or steam through your home’s hot water pipes to warm baseboards and iron radiators. Hot water, steam, gas, oil, hydronic air, and even wood or coal boiler systems are all options you might consider.

On the other hand, a furnace runs on the type of heat (gas, propane or electric) that runs through your home. Hot air travels your home’s duct system and vents to warm your home.

Boiler vs. Furnace: Which Is Better?

These categories break down the boiler versus furnace debate, which will help you decide which heating system is right for your home.

Size and Appearance

Older water boilers are typically quite tall and cylindrical. “Most boilers manufactured in the last 40 years or so are rectangular in shape,” says Jeff Botelho, Expert Review Board member and plumber. “Up until the invention of direct- and power-vent models, they could be found closer to the chimney for exhausting purposes. Today, regulations specify that they go along the wall of your home, which is why most are in the basement or garage.”

Older furnaces are small and rectangular. Today’s newer models have tight clearances and fit in much smaller spaces—such as your garage, attic, or inside of a utility closet—without much clearance aside from what is required to remove access covers. Keep in mind that you should always install furnaces with at least a foot of space around every edge to keep them from overheating.


Whether you install a water boiler or air heating system, buying a heating system for your home isn’t cheap.

  • Gas boiler prices range between $3,500–$10,000+
  • Furnace prices range between $700–$2,000

You’ll pay the most for furnaces that run on oil, while high-end boilers with extreme efficiency can easily surpass five figures. (But keep in mind, these prices reflect the cost of the system, not operating or installation costs.)

Installation and DIY

Both boilers and furnaces are tricky to install. In some states, it’s illegal to attempt the job yourself. Depending on its power source, you could be dealing with electrical lines, gas lines, or oil tanks—which means it’s better to hire a pro to install a boiler or furnace.

Expect to pay another $2,000 to $8,000 on installation costs for either type of device. Furnaces are an easier job, which may mean you’ll pay less.

Energy Efficiency

Boilers cost more than furnaces, although each heating system will cost about the same to run throughout the winter.

Gas furnace prices are generally lower than electric furnaces, meaning you can save lots of money by switching to gas if you’re heating your home frequently.


When it comes to maintenance and potential repair costs, modern, high-efficiency boilers are far more expensive to repair than other heating equipment. They also require annual service.

When well-maintained, you can expect your water boiler or hot air furnace to last between 10 and 20 years. A boiler may last slightly less. Consider the cost to repair a furnace before choosing it to heat your home.


Both pieces of equipment vary when it comes to repair costs, making the boiler versus furnace conversation a bit tricky. A simple boiler leak can compromise your system and be more costly to repair than your average furnace issue, with the national average for boiler repairs being $395.

Because furnaces use hot air instead of water, there’s no risk of it freezing during very cold weather. Still, the average cost for furnace repairs is $280.


Furnaces and boilers both have potential safety concerns, most of which won’t be a problem if you maintain your unit.

Furnaces require service once a year. During the inspection, a furnace installation specialist can tune up your machine and ensure your family isn’t exposed to carbon monoxide.

“Furnaces also require air filters, which you should periodically replace,” says Botelho. “The time between filter replacements relies on many factors, including how dusty the space is, the construction of the building, and how often doors and windows are left open.”

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Boilers require less maintenance overall, but since water and electricity do not mix, most repairs are needed immediately if something goes wrong.

Which Is Best for Your Home: Boiler vs. Furnace?

The type of home you own or where you live can also help you settle on a boiler versus a furnace.

Which Is Best for Your Home in Cold Weather Climates?

Boilers offer steady heat distribution throughout the home. Some find the circulation of hot air through the home off-putting or uncomfortable. If you live in a cold-weather climate where you’ll use your heating system several months out of the year, this could be one reason to install a boiler radiator system.

Which Is Best for Older Homes?

Furnace heating systems are generally quieter than boilers, so if an older home has appropriate ductwork installed (or you can afford the expense), it might be better to choose air over water.

Installing 150 feet of new ductwork (about average for a 1,000- to 2,000-square-foot home) will cost between $1,500 and $3,000.

Which Is Best for Smaller Homes?

Furnaces are better than water boilers for small homes. They take up less space and can fit in utility closets, which frees up potential living space you might lose with a water boiler.

Boiler vs. Furnace vs. Heat Pump

A third type of heating system you might consider is a heat pump, which brings warm air from outside during the colder months and removes warm air from inside during the summer.

Heat pumps, unlike boilers or furnaces, collect heat instead of distributing it through air ducts or pipes. This type of home heating system is much more efficient than a boiler or furnace and comes with the added benefit of removing humidity from the air.

However, maintaining a heat pump is a much bigger job than a boiler or furnace. The fans, filters, and coils must be monitored and changed out every couple of months.

Know what you need for your home? A local boiler installation specialist (or furnace, whichever you’ve decided) can help you keep your home warm all year round.

Ready to start your boiler or furnace installation?


  1. Mike, May 21:

    The efficiency numbers are very outdated. Modern gas fired furnaces can be > 98% AFUE. Same with gas fired boilers.

    A furnace can actually be healthier than a boiler since it can constantly recycle and filter the air in the house.

    In my experience, on average boilers are similarly priced and have a similar time and complexity to install as furnaces. Usually 1-2 days for both.

    Honestly under DIY it should just say don’t do it, period. These are not DIY projects. Additionally there is a lot more to consider, such as correctly sizing the equipment for the house and its pipes/ducts if they are already present. It is more often than not incorrect to simply replace equipment with new equipment of the same size.

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