Feb_wk3_022118 |

The short answer is both. According to energy.gov, older furnace or boiler systems were only energy efficient in the 50-70% range.

That means a good amount of the fuel you bought to heat your home Went to waste. The boiler and furnace systems of today can have an energy efficiency rating of as high as 98.5%. The pros and cons of each system go beyond energy efficiency. Homeowners use both for differing reasons.


Your furnace heats air that is then distributed by your home’s duct system. They can run on electricity, natural gas, propane, or oil. Since air doesn’t transport heat as well as water, the system tends to be less energy efficient than boiler systems. However, high-efficiency furnace systems can provide the most efficient energy use of any available equipment when used properly.


●    Less expensive and easier to install.

●    No freezing hazard in winter.

●    More common than boiler systems which means they are easier for local HVAC companies to maintain or replace.


●    Generally less efficient than boilers.

●    More noise since you hear air traveling through the ductwork and vents.

●    Some rooms may be hotter than others at the same thermostat setting.

●    Furnaces can blow allergens and dust along with the hot air. Also, the air is drier in winter weather.



A boiler system is an enclosed water system where the fuel heats water into steam which is moved through the house and dispersed through radiators or radiant floor systems. Water has better thermal properties than air which means the water in your boiler will retain heat for longer.


●    Boilers use less fuel to heat your home and can run on the same fuels as a furnace with the added benefit of the ability to use biodiesel blends.

●    The heat produced by boiler systems is much more consistent which means all rooms will be at or near the target temperature.

●    Less running noise.

●    Boiler systems do not need air filters which reduces the added expense.


●    The typical boiler system cost $5000 – $10,000 to install making them considerably more expensive to install than furnaces.

●    It takes longer to feel a temperature change with a boiler system when you change the thermostat.

●    Boiler systems are more expensive and difficult to remove and replace.  Also, converting from a boiler to a furnace is very expensive as you will need to install the proper ductwork throughout your home. This also means you can’t combine your boiler system with your air conditioning.

●    Boilers can leak. There is a danger of the pipes freezing in the winter if the system goes down and you can’t get it repaired in time.

Despite all its benefits, the cost associated with boiler systems means they are much less common than furnace systems and used mostly by homeowners that are concerned with air quality. Regardless of the type of system you have, it’s important to know what system you have in your house, its age, and how it works since you are the first line of defense if something goes wrong. If it does, call Legacy Mechanical, regardless of the system, we can get you up and running.