Differences between boiler and furnace: what is the best option? (You Didn’t EXPECT this!)

When you’re trying to decide which heating system is best for your home, it can be difficult to know what the differences are between a boiler and a furnace. When you call a plumber you also have to know which one of the two you have so that they can send the correct technician. Let’s take a look at how you can distinguish between them.

A boiler is traditionally used in homes that heat water. This can be used for heating or warm water. When the hot water heats up, it goes through pipes and heats the house. These often work on natural gas, electricity or oil.

Radiators on the other hand don’t heat water but they heat air. For this reason, they don’t offer warm water but only heat.


To keep it simple: if you have radiators in some rooms, you have a boiler. If you have ductwork and heat panels on your floor, you have a furnace.

What is a boiler and what does a boiler do?

Boilers are often more advanced than water heaters. Water heaters just heat up water. Boilers can often heat up water and radiators with the same device. Older systems just heat up radiators though. These systems have evolved a lot in recent years and have become more efficient. For this reason, a lot of people pick a combi system where the boiler heats up the water and the radiators.

There are tankless systems and also boilers that have a tank. A tank holds hot water and this makes the system more efficient if you use a lot of hot water. The boiler doesn’t have to start every time you open up the faucet to get hot water. Tanks are more expensive to install and are not useful if you don’t use a lot of hot water. For this reason, tankless systems are often used in apartments or for smaller families.

These systems often last up to 10-15 years if they are well taken care of. You have to get it inspected every 2 years and flush the system to remove sediments. You also want to check if there are leaks from time to time. 

What is a furnace and how long do furnaces last?

A furnace can be used to heat air. This is accomplished by burning fuel, like oil, natural gas or propane. The heated air leaves the furnace and heats your house using ductwork.

This is one of the most common heating systems for homes in North America. It is cheap and easy to install and leaks are less of an issue. 

These systems generally last up to 10 years. It is important that you clean the air ducts from time to time. This can take quite some work. 

How can you tell if you have a furnace or boiler?

The easiest way to tell if you have a furnace is by seeing if you have ductwork. If you have ductwork, then there’s a good chance that your home has a furnace. 

Ductwork is often located in the floor. It is generally covered by a metal plate. If you hold your hand over it, you should feel warm air when the furnace is working.

If you’re not sure whether or not you have ductwork, the easiest way to check would be to look in your basement. You can usually see the vents leading from the rooms up into the floor. 

 A boiler often uses radiators. These are easy to see as they are installed on the wall and take up quite a lot of space. More recently floor heating is becoming more popular and this is harder to detect as it is installed under the floor. You can also look up the brand and model number online to check what type of system you have. This model number is often found on the cover plate of your device. It is also printed on your manual. You can also contact the company that installed your device to see what they have on record. 

The best heating system for your home: difference between boiler and a furnace

Each system has its unique advantages and disadvantages that you have to take into account when you decide which one to pick.

Boilers are often more efficient than furnaces. This can make you save on your energy costs. They also don’t push dirty air in your house. A lot of people don’t clean their ducts and this can lead to unclean air being pushed into your house. 

Boilers in combination with floor heating can be very comfortable. 

 Furnaces are cheaper and you have less chance of water leaks that can create a lot of damage in your house. They are easier and faster to install as well. Furnaces might be less comfortable though and require more maintenance. They also last less long. If you live in a warmer climate and don’t have to use the heating system often, installing a furnace might be the best option. If you need a lot of heating, it can be best to pick a boiler. You can discuss your needs with your plumber to see which system works best. 

More recently we see that people are starting to choose heat pumps as well. These take their energy from under the ground (geothermal) or air. These systems don’t need natural gas and are therefore more environmentally friendly. They still need a lot of electricity so you might need to install solar panels as well to keep it interesting. This technology is still evolving a lot so it will be interesting to see if it can become more efficient in the years to come. 

A boiler that has been cut open. We can see the inside of the copper tank that holds warm water. Image by PlumbingInstantFix, all rights reserved.

To conclude, we can state that there are big differences between boilers and furnaces. While boilers warm up water, furnaces heat up air. This results in a big difference in how they are installed. Now you know what these systems do, you can see what you have in your house or what system would work for you. In warmer climates, a furnace is often installed in combination with a water heater. In colder climates, people tend to pick boilers as they are great for heating up cold houses. Boilers are more expensive but last longer. You have to see what is important for your situation when you chose between these two options.