Furnace vs Boiler debate

This is not often a debate on which one you should choose. Most homes have one or the other already. You’re likely here because you’re trying to determine the pro’s or con’s of a furnace vs boiler.

As an example, in older semi or detached homes you could come across an old radiator system and may be wondering what exactly it is. After all, you’re likely used to seeing a natural gas furnace in most modern homes. You just press a button on your Nest thermostat and it heats right up! 

In many homes pre 1960 though, homes didn’t have the same ductwork that they have today- which is known as a “forced air” system that allow you to have a natural gas furnace.

You will find people that are passionate on the topic of furnace vs boiler as well. Both have their benefits and limitations. Firstly:

What’s the Difference Between Boiler Radiators and Furnaces?

Both units keep your house warm during the cold winter months, but the major difference between a boiler and a furnace is that a boiler uses water, while a furnace uses hot air.

Boilers, such as a Viessmann brand distribute heat generated from boiled water or steam through your home’s hot water pipes to warm baseboards and iron radiators. Hot water, steam and gas are the most common models although you’ll likely find older versions with oil or even coal!

A furnace runs on the type of heat (gas, propane or electric) that runs through your home. Using your home’s ductwork system for distribution, hot air travels through vents to warm your home. It’s the same ductwork that pushes cold air through your home via a central air conditioning system.

Boiler vs. Furnace: Which Is Better?

To break down the boiler versus furnace debate, we’ve created a few categories for you which will help you decide which system is right for you.

Size/Appearance of a furnace vs boiler

Both boilers and furnaces are likely in the basement. Water boilers are typically quite tall and cylindrical. Regulations require them to be installed along the wall of your home, which is why most are in the basement or garage.

Furnaces, on the other hand, are smaller and rectangular. Their smaller size allows more flexibility on location. Most often they are found in the middle of the basement near ductwork, but they could also be up high towards the ceiling if needed.

Keep in mind that you should always install furnaces with at least a foot of space around every edge to keep them from overheating.

Cost of a furnace vs boiler

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

  • Boiler systems are very expensive, sometimes in the range of $25,000 installed but a good system will last 40- 50 years. 
  • Furnace prices are typically in the range of $5000-$7000 installed and last about 25 years if maintained properly. 
  • If you’re installing a furnace, many people choose to add a central air conditioning unit at the same time. Companies will offer discounts to do both at the same time since the technician is there anyways. Central air conditioning units cost roughly $4000 installed.


We’d suggest you call in the pros on this one. When you start dealing with gas and water, it can quickly get out of hand. Not to mention that your insurance company probably wouldn’t be pleased to hear about a DIY job.  Depending on its power source, you could also be dealing with electrical lines.

Beth and Ryan personally use and recommend AIDO Climate Solutions. Call them and tell you we sent you!

Energy Efficiency

Boilers cost more than furnaces, although each heating system will cost about the same to run throughout the winter. In some cases, a boiler that runs on steam may cost more than one that runs on gas or boiling water.

Gas systems are relatively cheap to run. The average Guelph utilities average $75 per month to run a gas furnace and AC system in Guelph. 


When it comes to home maintenance and potential repair costs, a boiler is definitely the superior choice. Boilers require very little maintenance after initial installation. 

Furnaces on the other hand can break down at the least convenient times. Often times you can replace parts to keep the unit going but inevitably the unit is going to go. We’d also recommend annual furnace maintenance to stretch the life out.

Which Is Best for the Guelph winter climate?

Boilers offer steady heat distribution throughout the home. Some find the circulation of hot air to uneven or even uncomfortable. 

Furnaces on the other hand could offer more even distribution of hot air on main levels. The higher the house goes, the further the air has to travel. 

If you have a 2 storey, 2.5 storey or even 3 storey home, you may notice less even heat distribution.

Do you have young children? 

If you’re moving to an older home that has the upright, century old radiators, you should consider that these can get very hot. These could burn a young child if left unattended. It may be worth calling in a professional to give you more modern options.

Furnace heating systems are generally quieter than boilers, so if an older home has appropriate ductwork installed it might be better to choose air over water.

Which Is Best for Smaller Homes?

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

So, if you live in a townhouse or condo, you’ll likely always want a furnace.

Furnace vs boiler for cooling

If you are considering a house with a boiler system, a major factor to consider is air conditioning. A home with a boiler doesn’t have ductwork and therefore is not compatable with central air. This may be a deal breaker for some.

There are options though if you’re considering a home with a boiler system. The main option is a ductless model. These are wall mounted on the interior, typically above doorways. From the outside, the unit has refrigeration lines that come into the house at specific locations and provide cool air.

The other option are the more common window units which you’ve likely seen.  These units fit into an open window and provide cooler air- the main downside here is that you lose the use of this window itself.

This post is part of a larger series that Beth and Ryan have created titled “16 Things to Consider When Buying an Older Home“.