As winter approaches, you may be thinking about replacing your heating system… and your first question is probably, “Which system is best for my home, a boiler or a furnace?”
Here’s the answer: the heating system that’s “best for your home” will depend on your budget and the features that are most important to you.
When evaluating whether a boiler or a furnace is the better system for your home, you should consider the differences in:
- The way heat is delivered
- Energy efficiency
- Air quality
- System replacement cost
Below, we will go into each of these factors in more detail, so you can get a better idea of which heating system is best for your home and lifestyle.
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Factor #1: The way heat is delivered
Boilers heat your home with heated water. This water is sent throughout your home in pipes and the heat from that water is released via radiators or radiant floor systems.
Furnaces heat your home with heated air. A furnace sucks in air from your home, heats this air, and then blows the heated air throughout your home via air ducts.
Both of these systems can sufficiently heat your home, but some homeowners have a preference on the way heat is delivered.
Because boilers don’t use heated air, there is no draft when your home is being heated. Some homeowners experience a draft with a forced-air system, like a furnace or heat pump.
Boilers provide natural zoning (you can control the heat of each room individually via the radiator in that room), whereas zoning with a furnace would require the installation of multiple thermostats.
3. Consistent temperature
Boilers run for longer periods of time than furnaces do, which allows the heat more time to evenly dissipate across your home. This creates a more consistent temperature around your home compared to furnaces which turn on and off more quickly, sometimes resulting in hot and cold spots.
4. Temperature response time
Furnaces are able to quickly react to a change in temperature on the thermostat, where boilers take a little while to change temperature. So if you want to change the temperature by a few degrees, your furnace will respond much faster than a boiler can.
Factor #2: Energy efficiency
The efficiency level of both boilers and furnaces are rated with a measurement called AFUE (Annual Fuel Utilization Efficiency). Essentially, AFUE measures what percentage of fuel used by the system is turned into heat and what percentage is turned into waste.
For example, if a boiler has an AFUE of 90%, it means that 90% of the fuel used by the boiler will be turned into heat and 10% of it will be lost as waste.
Even though boiler and furnace efficiency are rated on the same scale, if a boiler and a furnace both had an AFUE of 90%, it doesn’t necessarily mean they are operating at the same level of efficiency.
Boilers tend to be more energy efficient because the heat (heated water) is contained within insulated pipes, so there is little to no heat loss as the heated water travels throughout your home.
On the other hand, furnaces move heated air through your home via air ducts, which are typically located in unconditioned spaces like the attic. This usually means there will be some heat loss as the heated air makes its way through your home. In addition to this heat loss, ENERGY STAR reports that 20 to 30% of conditioned air is lost from holes and loose connections between ducts, making a forced-air system (like a furnace), less efficient than a boiler.
Factor #3: Air quality
The bottom line is this: Without a quality air filter, a boiler will probably be the better system for air quality because it doesn’t kick up dust and other pollutants/allergens. However, with a high-MERV filter, a furnace will be the better option for air quality because it can actually remove allergens/pollutants from your home.
Let’s look at this in a little more detail:
A forced air system, like a furnace, heats your home by blowing heated air through it, which also means that any allergens, dirt and other pollutants in the air are circulating your home as well.
Because boilers heat your home through steam, they do not circulate the pollutants listed above, which generally means they won’t stir up pollutants that aggravate allergies and respiratory problems.
However, although boilers don’t stir up pollutants, they don’t work to eliminate them either, whereas a furnace CAN eliminate allergens and pollutants, depending on the filter you install with it.
If you pair your furnace will a high-MERV filter, a furnace can provide better air quality than a boiler. That’s because high-MERV filters (11+) catch small particles like pet dander, mold spores and dust mites as well as contaminants like bacteria and tobacco smoke.
We know this is slightly confusing, so if air quality/reducing allergens is high on the priority list for you, you should speak with a technician before installing a heating system. An experienced pro will be able to talk with you about your options and find a solution that will work for you.
Factor #4: System replacement cost
Furnaces are typically cheaper to replace than boilers.
The main reason is because boilers require a lot more infrastructure than furnaces do, so they cost more to replace.
Boilers typically cost anywhere from $5,000 to $10,000+ whereas furnaces usually cost $4,500 to $10,000+.
That being said, those prices only include the cost to replace units if you already have them—not the cost to install them from scratch. For example, the cost to install a boiler if you've never had one before would be a lot more expensive than the prices listed above because you'd need to factor in the cost of adding radiators and additional piping in every room. In the same way, if you need to repair or install ductwork, the cost of a furnace can greatly increase as well.
Read more about the cost to install a furnace on our blog, “How Much Does it Cost to Install a Furnace in Pittsburgh?”
Ready to install a new heating system? Hire Calfo
Whether you’re still unsure which type of heating system you want/need for your home or you’re ready to install a boiler or furnace, we can help. We’d be happy to talk through your budget and heating needs to help you figure out which solution would be best for your home.