Family of 4 together at home - Furnace vs. Boiler

Both boilers and furnaces are used in Canadian households, but which heating system is better? There’s a lot to consider when evaluating heating equipment, from cost to efficiency, maintenance, and more. 

We compare and contrast boilers and furnaces so that you can make an informed decision about buying a furnace for your Toronto home or choosing a Rinnai boiler for your household.

How Does a Boiler Work?

Boilers heat water and use that water—or the steam it produces—to heat your home. 

First, a fuel source, such as natural gas, oil or propane, heats a heat exchanger within the boiler. The hot water or steam is then distributed throughout your home via pipes. The boiler heating system delivers heat to each room via baseboard radiators, cast iron radiators, or even radiant flooring systems. When the water cools (or the steam condenses back into water), it typically flows back to the boiler, allowing the process to start all over again.

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How Does a Furnace Work?

Furnaces heat air (vs. water), and that hot air is used to heat your home.

Typically, natural gas combustion generates heat inside a furnace, but electricity, oil or propane can also be used to warm a heat exchanger. A fan then pulls air over the heating element, warming it up. Next, furnaces blow hot air into your home’s duct system. Forced air systems like these deliver toasty warm air to all areas of your house through vents in each room.

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Difference Between Boilers & Furnaces

Now that you know how each heating system works, it’s time to take a closer look at the differences between them. The details below will make it clear if a furnace or boiler is right for your home.

Cost Comparison

When faced with choosing a boiler vs furnace to install, the cost is likely to play a huge role in your decision. 

Overall, installing a natural gas furnace system is less expensive (and electric furnace installs are even cheaper). Boiler installations are pricier because the unit itself costs more and installation is more complex. One reason is that boilers tend to be heavier than furnaces.

Many factors will determine the ultimate cost (such as model, size, fuel source, etc.), but, in general, a furnace can be installed for between approximately $2,500-$6,500+. A boiler, on the other hand, has an initial cost of anywhere from $3,500 – $10,000+. Fuel source and the type of boiler you choose directly impact the cost.

Efficiency Ratings

The energy efficiency of your furnace or boiler will also influence cost—upfront and long-term. 

Ideally, you want to purchase a heating system with a high annual fuel utilization efficiency (AFUE). A high AFUE rating (of 80%+) means a high percentage of fuel is converted into usable heat, lowering your fuel costs over time. Boilers and furnaces with ENERGY STAR status have an enviable AFUE of 90% or higher but do come with a higher initial price tag.

Homeowners with older homes should note that their older residential furnaces and boilers undoubtedly have a low AFUE rating (below 70%). While it’s possible to increase the energy efficiency of older heating systems (by hiring an HVAC professional to perform a furnace or boiler system audit and making retrofits to reduce heat loss), purchasing an energy-efficient heating system is 100% worth it over the long-term.

Environmental Impact

Any heating system—boiler or furnace—powered by natural gas produces carbon emissions. 

Gas furnaces, tasked with heating air, require more energy—and thus more fuel—than boilers do to heat water. For this reason, boilers are generally considered to be more sustainable. As we discuss below, some boilers can last longer as well, so replacement may not be needed as often. However, electric furnaces do not produce any emissions, and many are energy efficient, making them a very environmentally friendly choice.


Furnaces and boilers work in different ways, but overall, they have similar lifespans.

A furnace typically lasts 15-20 years, and most boilers will last at least that long or longer. (Some have been known to last up to 30 years.)

What determines the lifespan of a heating system is the type of unit you have, its efficiency, usage and degree of maintenance. Newer, high-efficiency furnaces with advanced technology that are adequately maintained will far outlast a traditional furnace.


All heating systems require regular checkups and cleaning to ensure everything works perfectly (and safely) when needed. The best way to ensure this happens is to subscribe to a maintenance program or a furnace protection plan. Plans like these protect your investment and catch minor problems before they become expensive repairs.

Furnaces tend to need a little more attention than boilers do, mainly because air filters need to be replaced often (a simple task most Toronto homeowners can do) but also because they are commonly gas fueled. Boilers also require regular maintenance. For safety’s sake, only trust qualified HVAC professionals, like the experts at Husky, to perform any boiler repairs or adjustments.


Boilers, as closed systems involving water, are known to be less forgiving when it comes to sizing. That said, proper sizing of any heating system matters—a lot! 

If your boiler or furnace is undersized, it’ll struggle to produce the heat you need. This stresses the components and results in uneven heat throughout your home. On the flip side, oversized systems are entirely inefficient; they produce more heat than you need, ultimately wasting energy (and money). 

How do you make sure your furnace or boiler is appropriately sized? Ask an HVAC professional to perform a detailed load calculation. The technician will consider the climate, square footage, the number of doors and windows, the quality of insulation, and other factors when determining the best size for your heating system.


A furnace or boiler can meet your household’s heating demands when properly sized and maintained. Despite this, comfort means different things to different people, and each system does have advantages and disadvantages. 

For example, many furnaces are compatible with air conditioning units, conveniently allowing you to incorporate cooling into your HVAC system. Alternatively, if humidity is important to you, a boiler system (using water to create heat) increases the moisture content of the air as compared to the air distributed by a standard furnace (without a humidifier enhancement). Also, some people feel that boilers can make a space feel hotter than a furnace.


When a boiler or furnace is correctly installed and regularly maintained by an HVAC professional, either system is safe to use, but there are always things to be aware of.

A fire risk exists for any heating system that requires fuel, such as gas, propane, oil or electricity, to run. Again, proper maintenance is key to reducing this risk. Also, these units can produce dangerous carbon monoxide, so having a carbon monoxide detector is essential. 

Other safety concerns are more system specific. Boilers heat water, so leaks are a concern, and the temperature of the water can cause injury if it gets too high. Gas furnaces should be monitored for gas leaks, and forced air systems can negatively impact the air quality in your home if filters are not changed or if your ductwork is improperly sealed.

Husky Is Here To Help

The decision to install a boiler vs. furnace comes down to the heating needs of your family and the layout of your home.

The award-winning experts at Husky will assess your household requirements and provide a list of all the options available to you. We’ll discuss the functionality of different brands and models and find a solution that works for your home and your budget.

Call us at 905-761-9485 or Request a Free Quote