Furnace vs. Boiler: What’s the Difference?

San Rafael

(415) 942-6565

Santa Rosa

(707) 452-3464

There are multiple different methods you can use to rely on heating for your home, including heat pumps, furnaces, or boilers. When it comes to furnaces and boilers specifically, there is often some confusion on what differentiates the two. For a basic explanation, a furnace will use forced air in order to provide heat for your home, while a boiler utilizes water to give the entire house heating from things like radiant flooring systems. You may be wondering what the specific differences are or which heating appliance will be the best heating system choice for your home.

This article will look at all of the differences between boilers and furnaces, including their specific functions and appearances, lifespan, maintenance requirements, costs, and energy efficiency. We will then discuss some pros and cons of each system type before telling you how you can decide whether a furnace or boiler is right for your home.

Furnaces and Boilers — Differences Between Heating Systems

Function and Appearance

Hot water boilers or steam boilers heat water by using either natural gas, propane, electricity, heating oil, or even wood pellets as a source of fuel, sometimes enough to turn it into steam. The hot water or steam is then sent through a system of pipes towards the radiators placed throughout the home. This hot water or steam can be sent to things like wall heaters, radiant floor systems, cast iron radiators, or baseboard radiators. A boiler will typically need a separate air conditioning system, but it can sometimes be paired with a water heater or work as a combination boiler and water heater on its own.

A furnace is a forced air system where natural gas, oil, electricity, or propane is used as a fuel source to warm a heat exchanger. The air is pulled in and over this heat exchanger and combustion chamber and is then pushed through the duct system with a blower fan. The heated air is then distributed throughout the house through the vents. A furnace can usually be combined with a central air conditioning system. Natural gas furnaces are the most common.

A boiler is a much larger and more industrial-looking unit, while a furnace is smaller and more box-shaped. A boiler vs. a furnace will take up a lot more room since it needs a tank to store the hot water.


Boiler systems will last much longer than a furnace because of all of the components involved in a furnace, such as the combustion chamber, the home’s duct system, and so on, that make them more susceptible to damage. With regular maintenance and upkeep, boilers can last up to 30 years, while furnaces only usually last up to 15 or 20 years.

Maintenance Requirements

Regular tune-ups are required to keep any system running smoothly for the full extent of its lifespan, but there are slight differences in maintenance when it comes to furnaces and boilers. A boiler system will require fewer regular checkups than a furnace since it does not have as many moving parts as a furnace does. Furnaces will require things like changing air filters, duct cleaning, and checking the components for possible failure, since there are so many of them. These tasks have to be performed every few months. Boilers, on the other hand, usually only require a once-a-year inspection. A furnace will require a yearly professional inspection as well. This is important for both heating systems since there is the danger of carbon monoxide poisoning if something goes wrong with either one; therefore, a technician should give it a look on a yearly basis.


The installation cost of a boiler vs. a furnace would be much higher. Installing a new boiler system can cost anywhere from $5,000 to $12,000, depending on the model and fuel type. A furnace installation will cost between $2,000 and $7,000 on average. What will mostly determine monthly running costs and repair costs is the type of system you get as well as the fuel source it uses. There are also things like your home’s heating requirements, which will determine how much energy needs to be used to comfortably heat the whole house.

Energy Efficiency

You can compare the energy efficiency of a boiler vs. a furnace using their annual fuel utilization efficiency ratings. AFUE ratings are determined based on the type of boiler and the heating source (natural gas, oil, etc.). Heating water requires less energy than heating air. Since a boiler heats water and a furnace heats air, boilers are considered more energy efficient than furnaces. There are energy-efficient models for both heating systems that will lower energy usage and monthly running costs but will be more expensive in upfront costs.

An even more efficient heating option is a heat pump, which takes warm air directly from outside and transports it inside, working in reverse for cooling. Heat pumps are less expensive to operate since they are not creating heated air and are instead moving outside air inside your home. Since furnaces actively heat air and boilers actively heat water, they take up more energy than heat pumps.

Pros and Cons of Boilers and Furnaces

So what are the pros and cons of a boiler vs. a furnace?

Most boilers offer fewer maintenance responsibilities, more comfortable heating with radiant heat, energy efficiency, less noise when running, no required ductwork, and water that can be safely reused in a cycle rather than constantly refilled. The hot water a boiler heats can even be used in some boiler systems for things like showers, sinks, and dish washers. The radiant heat is also more consistent.

On the downside, boilers are much more expensive, and they run the risk of water leaks that can cause extensive damage to your home.

Furnaces, meanwhile, take much less time and money to install, and they can be paired with a central air conditioner with the same ductwork so that you have a heating and cooling system all in one.

However, they run the risk of creating a drafty environment within your home, as well as requiring a lot more time spent on maintenance tasks. There are also a lot of allergens that can be recirculated through the hot air in forced air systems, creating a particularly bad environment for people with allergies.

Furnace or Boiler — Which Heating System is Best?

Deciding which heating system is the best option for your home will depend on things like the heating requirements of your home, the climate where you live, your budget, and the specific type of boiler or furnace system you are wanting to get. A boiler is far more expensive upfront, but it will be more energy efficient in the long run. Furnaces require a lot of time for maintenance, but it will take far less time and money for the installation process, and you can connect an air conditioner with it.

A good way to know which heating system will be the best for your home is to consult with heating and cooling experts. John Owens Services has years of professional experience in the HVAC industry and can help you analyze every aspect of your heating needs so that you can make the best informed decision about which system you want to go with. Apart from that, we provide excellent installation, repair, and maintenance services. There are dangerous parts involved with furnace and boiler installation, such as steam and electricity, that you can rest easy knowing are being handled by licensed professionals so that no harm comes to you or your home.

Boilers and furnaces can be essential in providing you with heat, so you want to be sure they are installed to perfection. We have boiler and furnace pros who can assist with every aspect of your new furnace or boiler and can provide an annual inspection as well, so that you can always rely on having warm air in your house. From wall and baseboard heaters to ducts, we can offer installation, repairs, and maintenance for all aspects of boilers and furnaces.

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San Rafael
(415) 942-6565
Santa Rosa
(707) 452-3464



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San Rafael
(415) 942-6565
Santa Rosa
(707) 452-3464