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Furnace vs. Boiler: What's the Difference?

Written by Carol J Alexander

Published on February 7, 2023


Furnace vs. Boiler: What's the Difference?

Learn the difference between a furnace and a boiler and how each works so you can choose the right option for your home.

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It’s easy not to think about your heating system until it stops working correctly. Then, it helps to know what type you have so you can get help. A furnace takes in air, heats it, and then distributes the warm air throughout the home through a series of ducts. A boiler heats water and then pumps hot water or steam through a series of pipes to radiators in every room or through tubes in the floor. The main difference between the two is that a furnace heats your home with air, and a boiler heats your home with water or steam.

In this article, we’ll discuss how boilers and furnaces work, the pros and cons of each, and which option is right for your home.

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Furnace vs. boiler: how do they work?

When you own a home, it’s essential to understand how different components in your home function, particularly when they provide comfort and safety. Let’s look more in-depth at how a boiler and furnace work.

What is a boiler?

A boiler creates either steam or hot water to create hydronic heating. If you have a steam boiler system, it circulates the steam from the boiler to iron radiators throughout the house. If you have a hot water system, a pump moves the water throughout your home in two ways.

Older homes generally have baseboard radiators. Impellers throughout the piping system carry the water to radiators installed where you want to heat. In most homes, you’ll find a radiator in every room and hallway. Newer homes use hot water in a radiant floor system. A gridwork of tubes lies under the subfloor in the areas you want to heat. The heat radiates upward as the impellers carry the hot water through these tubes. Nothing beats radiant floor heating when you get up in the night for a drink of water.

With a boiler system, each area has a thermostat to regulate the temperature. So, if you have rooms you seldom use, like a guest bedroom, you can lower the thermostat in that area to save energy.

What is a furnace?

A furnace is a forced air system that uses a high-powered fan to draw cool air in, heat it, and blow it back out through the ductwork into the areas you want to be heated. Since the system draws air in, there is a filter on the intake you need to clean regularly.

Except for closing the vents in certain areas, there’s no way to regulate the temperature in different rooms of the house. Consequently, the area closest to the furnace gets the warmest air. Then, as the hot air travels through the ductwork, it cools slightly before reaching the room. 

What are the pros and cons of furnaces and boilers?

Whether replacing an old HVAC system or building a new home, consider the pros and cons of furnaces and boilers.

Pros and cons of a furnace

  • + Lower installation costs.
  • + Speed of installation is quicker. Installing a furnace only takes a few hours.
  • +
  • - No risks of water leaks. And, with loss of power, there’s no risk of the water freezing.
  • - A furnace will heat a cold home quickly.
  • - You can use a furnace in conjunction with a central air system.

Pros and cons of a boiler

  • + Evenly distributed, pleasant warmth.
  • + Silent. There is no fan to make noise.
  • - Higher installation cost.
  • - It can’t double as a source of air conditioning.

Is a boiler or furnace more expensive?

When comparing the cost of a boiler vs. a furnace, it’s important to note that the expense doesn’t end with the installation. So first, let’s look at the cost of installing a furnace and boiler and running them.



The factors that influence the cost of boiler installation depend on whether you’re replacing an existing unit or starting from scratch. When replacing an old boiler, you have the labor and the cost of the boiler. Installing a boiler is more costly than installing a furnace because of the piping that needs connecting.


When replacing a furnace, you may incur the cost of repairing or replacing some ductwork, which could run into thousands of dollars, depending on the type of furnace and the type of duct. Electric furnaces are less expensive to install than oil ones. High-efficiency furnaces cost more than those without an ENERGY STAR rating, depending on the size and type.


The cost of operating a furnace or boiler system depends on several factors. The first factor is the unit's efficiency rating, which is measured by the annual fuel utilization efficiency (AFUE). The AFUE is the appliance’s annual heat output ratio to the total fossil fuel energy it consumes annually.

Fluctuating fuel costs also have a significant impact on the cost of operation. Other factors are how warm you keep your home and the region in which you live.

Add the cost of routine maintenance to these factors, and you have the total cost to operate your furnace or boiler. Boilers need no more than a yearly inspection and cleaning by a professional. Furnaces also need a professional check-up each year, but as a homeowner, you’ll need to replace the intake air filter on the unit each month. Depending on the size and filtering abilities, a filter can cost between $5 and $50.

Is a furnace or boiler right for your home?

If you’re not replacing an existing unit, you may consider whether a furnace or a boiler is right for your home. In addition to the factors on the following chart, you’ll want to consider the implications of retrofitting both systems.

A furnace requires room for ductwork. Another system may be your best option if you don’t have a basement or attic to run the ductwork. However, a boiler system requires the installation of water pipes. You can retrofit a baseboard radiator more easily than installing radiant floor heating in an older home. But you’ll still need to access a basement or crawl space to install the pipes.

Time to warm up

Staying warm in the winter months is essential to most people. So choosing the right home heating system for you is an important decision. Whether you go with a forced-air heating system, hot water boiler, or heat pump, you’ll want to partner with a professional who knows the HVAC business and has a proven track record in installations in your region.

Get in touch with a local pro to install your furnace or boiler today

Written by

Carol J Alexander Content Specialist and Subject Matter Expert

Carol J Alexander is a home remodeling industry expert for Fixr.com. For more than 15 years as a journalist and content marketer, her in-depth research, interviewing skills, and technical insight have ensured she provides the most accurate and current information on a given topic. Before joining the Fixr team, her personal clients included leaders in the building materials market like Behr Paint Company, CertainTeed, and Chicago Faucet, and national publications like This Old House and Real Homes.