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Key Differences Between a Furnace and Boiler

working on gas heaterWhen it comes to heating our homes, the terms “boiler” and “furnace” are often used interchangeably to describe systems. While they provide the same result, operation is markedly different.

A furnace heats air before a motor pushes it through a series of ducts. A boiler heats water – not to be confused with a hot water heater – then passes through a series of pipes.

To better understand how the central heating system in your home works, learn the key differences between a boiler and furnace.

What Is a Boiler?

In a boiler setup, water is heated in a tank before it circulates in liquid or steam form through pipes. The water passes to different areas of your home, with the endpoint typically being a baseboard heater or radiator.

This process heats the surrounding area to make your home feel warmer. Other names for this type of arrangement are radiant heating or hydronic heat. Unlike a furnace, boilers do not use a series of ducts and tend to offer greater efficiency and less noise.

To heat the water, a boiler uses a few options for fuel, including natural gas, oil, propane or an alternative source like wood. If you have a gas boiler, a series of jets help the water reach its desired temperature. Meanwhile, electric systems operate similarly to a burner on the stove.

In action, boilers use a closed-loop system: The water that passes from the boiler through the series of pipes returns back to the tank, where it’s heated again. Because the process doesn’t have to repeat each time at full strength, your system uses less energy throughout the day to heat the returning water.

Long term, boilers require fewer repairs and waste less heat than a duct-based system, while consuming less energy. Generally, your system requires a single annual service appointment for repairs and maintenance and, depending on construction, can last years. You’ll also need to occasionally bleed the system for any excess air accumulation.

Not a Water Heater

There’s some confusion about the role a boiler fulfills, with many assuming this system also heats the hot water coming out of the faucet. Although both operate in a similar fashion, water heaters are part of the home’s plumbing and don’t use a closed-loop arrangement. A water heater ensures water is at the desired temperature before it flows to the faucet, shower or any other tap, before it passes down the drain.

What Is a Furnace?

Furnaces, whether gas or electric, are a forced-air system that uses a series of ducts. Beyond this general setup, operation varies. A gas furnace ignites fuel to start the combustion process, utilizing natural gas, oil or propane, and an electric model uses coils to heat the air inside. From here, the blower forces the hot air created through a series of ducts that pass through your home, where it emerges from a vent.

As a benefit, furnaces tend to heat a home in less time. Meanwhile, a boiler takes longer to heat the same amount of space. While furnaces are considered more traditional central heating systems, they come with a few drawbacks. Mainly, a larger percentage of air escapes from the ducts, occasionally creating a draft in your home, and this process consumes more energy for the same result as a boiler.

Also, maintenance for a furnace can be more involved due to potential carbon monoxide exposure risks. As such, not only should your furnace be serviced at least once a year but it’s also recommended to clean or replace the air filter at least monthly, if not quarterly. Forgetting to do so can cause the furnace to overheat and consume more energy.

With maintenance, further make sure you have the ductwork and not just the furnace cleaned for dust and dirt accumulation. Ignoring this step can allow allergens and other smaller particles to circulate through your home.

Yet, especially for those who live in colder regions, furnaces have one clear advantage over a boiler: Because the system doesn’t use water, you don’t have to worry about the pipes freezing and potentially bursting during winter.
Whether you own a boiler or a furnace, M.J. Fahy & Sons is here to annually service your home’s heating system to ensure its performance and address additional issues. To schedule an appointment, contact us today.