Furnace vs Boiler – What Are the Differences

furnace vs boiler featured image

Furnaces and boilers were originally invented to solve the problem of heat distribution. They heat from a central location, the furnace with air, and the boiler with water. The old fireplaces couldn’t cut it for the modern world – they made indoor life difficult.

The furnace/boiler options also rose out of a need to save energy. The boiler is the leader there, but only by a slim margin. Boilers are 95% efficient. Because furnaces use air, which loses heat quickly, warmth is lost through the ductwork, not the furnace itself. This loss can amount to 35%, which adds up to a lot of waste of energy resources over time.

A strict comparison between the two won’t help you make a decision, because there are many other factors to consider. Besides price, the major difference between them is air vs water, which frankly, for most people, doesn’t make enough of a difference to accept the disparity in price at the outset. A mid-range boiler will be between $2.5K and $4K. A high-efficiency boiler will be up to $10K, including installation.

If you add humidifiers and air purifiers, and your house and ductwork are properly insulated, and the building has good windows, you won’t need to make the considerable investment in a boiler. A furnace will meet your needs. But take a look at the rest of this article for some helpful hints on all the things worthy of your attention before you decide.

Up-Front Costs, Maintenance, and Longevity

A new gas boiler can be up to $8,000. A home furnace is almost always cheaper, which is why many choose that option. Many land developers take that option for the same reason, and as the buyer, you’re stuck with it – a replacement adds much (unrecoverable) to the costs.

With all the moving parts, a furnace requires a lot more maintenance. You must replace filters, and you might have to hire a professional to clean dust and dirt from ducts and intakes. A boiler has fewer moving parts, but at some point, you might have to address a broken circulator pump. A professional will likely charge you $400 or more.

DeWALT provides a comprehensive code reference on HVAC installations.

Air Quality and the Health of Residents

A boiler presents no concerns for health. Without forced warm air, you don’t have to worry about added dust and allergens. If you have someone in the home with eczema, asthma, or compromised immunity, you will have to consider your decision carefully. Boilers are definitely the more desirable option.

If you have concerns about air quality and for whatever reason, you’re stuck with a furnace, replace the filters regularly. This will also reduce your energy costs. A gummed-up filter forces your furnace to work harder and longer. A Premium HEPA activated carbon filter like this one from Nispira removes 99.97% of allergens. You also have some bulk-buying options that present further cost-savings.

reko lighting r2000 air purifier

When you have to be content with a forced-air furnace, an air purifier can also help. This purifier from REKO purifies the air using a UV-C light system and is designed to be installed on your HVAC Duct. An ozone lamp provides a portable option in this one provided by Dsane.

The radiation presents a safety risk, so follow operating instructions carefully. The lamp can’t operate with people or pets in the room, and the room must be ventilated for 30 minutes before entering. This table-top model from Jolight provides a smaller, more affordable option.

Remember that an energy-efficient design isn’t automatically a human health-conscious design. How to Build a Healthy Home provides an excellent resource if this is a concern.

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Heat Distribution

A boiler system is one that faithfully warms the whole house, especially if heat is distributed through the floor. Furthermore, you can make use of zone control with this heating system. This allows you to set different temperatures for different rooms and schedule those settings, something that is much more difficult with forced heated air.

The SmartZone-4X, 4 zone controller kit with a temperature sensor is universally compatible with a heating system and thermostat. This unit is easy to install and allows you to control zones remotely, which will be convenient while you’re on vacation or if you are spending most of your time in the kitchen and one bedroom – no sense wasting energy on empty rooms.

A furnace will leave you with cold spots, but you can mitigate this by leaving the fan on all the time. That uses up more power and places greater strain on the system and filters, however.

govee indoor temperature humidity sensor

If you want to improve distribution, inspect other parts of the house, including the attic and windows. Are the attic and ductwork well-insulated? Are the windows deteriorating?

Look for moisture seeping into the spaces between panes or crumbling frames. If the frames are plastic, look for warping, mold, and condensation. Replacements are costly in the short-term but will reliably solve many heat distribution and retention issues. This will also reduce drafts.

Here is an excellent resource for building a sustainable home.

Keep on top of temperatures in all areas of the house with more powerful sensors like this one from Govee, including thermometer, hygrometer, with notification alert and data storage for the furthest extremities of your indoor sanctuary: garage, sunroom, and basement – you name it.

“Smart thermostats” aren’t smart enough yet on their own to identify and address cold spots, but you can adjust settings through Alexa, such as this one from Sensi. These use Wi-fi to accept setting adjustments from multiple devices.

SmartZone-4X Control - 4 zone controller KIT w/Temp...
Govee Indoor Hygrometer Thermometer 2 Pack, Bluetooth...
Sensi Touch Smart Thermostat by Emerson with...
Google Nest Thermostat E - Programmable Smart...
SmartZone-4X Control - 4 zone controller KIT w/Temp...
Govee Indoor Hygrometer Thermometer 2 Pack, Bluetooth...
Sensi Touch Smart Thermostat by Emerson with...
Google Nest Thermostat E - Programmable Smart...
SmartZone-4X Control - 4 zone controller KIT w/Temp...
SmartZone-4X Control - 4 zone controller KIT w/Temp...
Govee Indoor Hygrometer Thermometer 2 Pack, Bluetooth...
Govee Indoor Hygrometer Thermometer 2 Pack, Bluetooth...
Sensi Touch Smart Thermostat by Emerson with...
Sensi Touch Smart Thermostat by Emerson with...
Google Nest Thermostat E - Programmable Smart...
Google Nest Thermostat E - Programmable Smart...


A furnace and the fan that distributes the heated air inevitably produce noise, but as long as the fan is not loose, it is white noise. You might even find the hum pleasant and calming, lessening the other din that comes in from outside. Some people who struggle with interrupted sleep choose to leave their fans running through the night for that reason.

lectrofan white noise sound machine

A boiler heating system is silent. (If you’re stuck with a boiler system, good news! You can have both: LectroFan makes this white noise sound machine!)


Forced air dries out everything. You will have dry skin and cracked nasal passages, which makes you vulnerable to viruses and bacteria. Plants, musical instruments, and wood furniture all suffer in a dry environment.

Some furnaces come equipped with humidifiers. If yours doesn’t, products like the Aprilaire Whole-Home Humidifier can help. This is a large-capacity unit capable of humidifying 3,000 square feet of space.

You can also find smaller, portable units that feature aromatherapy options like the Everlasting Comfort Humidifier with Essential Oil Tray.

aprilaire 500m whole home humidifier


As you can see, a boiler heats a home via the circulation of hot water, while a furnace heats a home vis the circulation of hot air. The air is then heated and distributed throughout the home through the vents and the ductwork. This is also known as forced-air heating.

For something quieter, then go for the boiler system. This way, you will not have to hear the hot air blowing through the system. A boiler system also requires far less maintenance as there are no filters that require cleaning. You will also find much better air quality since a boiler system doesn’t blow air. This means no dust or allergens are being blown throughout the home.

A forced-air furnace heats the home with natural gas or propane that is ignited in the burner. The furnace blows the heated air into your ductwork and distributes it. The average lifespan of a gas furnace is 15 to 20 years. So, with all this information, you should now see the many differences between a furnace vs boiler and what might work better in your home.

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