What’s the Difference Between Hot Boiler Radiators and Forced Air Furnaces?

Low temperatures outside call for a heating system that’s both efficient and cost-effective. Homeowners are often faced with many choices that are all vying for their dollar, but which model is the right fit?

If you live in a climate that has cold winters with temperatures predominantly below freezing, you’ll benefit from a boiler or furnace. Though both are excellent systems that keep you warm, there are some major differences. What are the factors that can help you decide which system best meets your needs?

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Forced Air Furnaces

Among the most popular heating systems installed in North America is the forced air furnace. These models create warm air within a heat exchanger. A fan then “forces” this air through ducts to heat your home. Furnace prices will be different depending on which type you choose.

Gas/Natural Gas

These run on natural gas ignited by a pilot light. There’s a heat exchanger that prevents any dangerous gases from entering your vents. Typically, natural gas runs through an underground pipeline, so you won’t need to refill a tank. Here are the average costs of a new gas furnace.

Propane & Diesel/Oil Fuel

Propane and oil models require fuel tanks that need to be refilled. Your system will draw fuel from these tanks to heat the air by a pilot light and a fan that forces the hot air through your vents.


Instead of using a pilot light and a medium, electricity heats the air, which a blower facilitates into your vents. It’s similar to the emergency heat mode on a heat pump— but more efficient and affordable version.

Wood Burning Units

These systems can be installed both outside or inside the home. They burn wood and then send the heat through a series of pipes, which then warms your home through a forced air system. The main advantage is that they can provide heat even during power outages.

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Hot Water Boilers

Boiler and pipes of the heating system of a house

Steam and boiler heating systems are among your heating options in cold climates. Put simply, boilers send hot water through a system of pipes that can heat your floors, walls, or baseboards through radiant heat. Radiant heat essentially radiates heat into the room. There’s far less energy waste compared to forced air and keeps the air more humid. If this system interests you, then explore the costs to install a radiant heating system.


These are also known as “standard” or “regular” and are typically found in homes larger than 2,500 square feet. For newer homes, you’ll need a unit that has a 55,000 BTU capacity. For older homes, you’ll need a unit with 82,000 BTUs.

Conventional boilers are known for how quickly they heat up a house. You’ll often see these models paired with radiant floor heating systems. The one precaution is that the heating power will depend on the size of your water tank.

Gas, Oil, or Electricity

These models heat water using various energy sources like natural gas, oil/fuel, or electricity. The prices and particulars of each system vary widely. Electric models are the most affordable, while gas boiler prices are middle-of- the-road, and oil units are the most expensive.


These systems are great for average-sized homes (between 1000-2500 square feet) and are one of the more affordable models available ($1,500). They store and heat water in a cylinder which has two tasks: 1) to deliver hot water to various rooms and 2) convert the water to steam to heat the home. Its eco-friendly nature makes it a great unit for homeowners who want to save on utilities and installation costs.

Hydronic Air Handler

Hydronic air handlers send hot water from a water heater into a hydronic heating coil. Then, hot air circulates through the coil and warms the air, which gets sent into ducts and out from vents. It works with tankless water heaters, synergizing to serve both hot water and home heating needs at once.

Wood or Coal

An outdoor wood boiler is known for being energy-efficient and working even when the power goes out. As the wood or coal burns, the system sends hot water through a series of underground pipes into your air ducts. The heat is then transferred using a heat exchanger, which in turn warms the house.


These units are made up of rows of cast-iron coils that are heated by steam or hot water. In turn, the coils radiate heat into the room. They’re one of the oldest methods of heating an interior but still are quite effective.

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What are the Differences?

How do these systems compare in cost, efficiency, ease of maintenance, and more?

Cost Calculator

Which unit is more affordable to purchase and install?

    • The cost of a furnace depends on the model you select but averages between $700 to over $2,000. Average prices by model include:
      • Electric: $700.
      • Gas: $1,200.
      • Oil $1,800.
    • Installation averages between $2,500 to over $6,000, including the price of the unit.

      • The average cost of a boiler depends on its quality and fuel type, but averages $3,500. High-end models can cost as much as $10,000.
      • Installation averages between $3,500 and $8,000.

The most affordable: Furance


A heater’s efficiency is rated by an AFUE percentage. AFUE stands for “Annual Fuel Utilization Efficiency”. Higher percentages mean that the system is more efficient. For example, an AFUE of 70% means that 70% of the energy becomes heat while the remaining 30% is lost.

      • Depending on fuel and model type, the AFUE rate fluctuates between 55% to over 95%. While you can expect systems manufactured before new eco-friendly mandates to be under 70% efficient (about 10-15 years old). Here are the average AFUE percentages for modern models.
        • Gas: 80%
        • Fuel: 80%
        • Electric: 95%-100%
      • Note: Figures don’t count the AFUE lost in ducts, which can be as high as 35%.

      • These also have variations in AFUE percentages.
        • High-efficiency water tank units: 90%
        • High-efficiency steam boilers: 82%
      • There’s no AFUE loss in ducts.

The most energy efficient: Boilers

Operating Price

After the unit is installed, which one gives you more utility savings?

Technician servicing the gas boiler for hot water and heating


The prices vary based on the energy source you use. Local prices for fuels and natural gas will fluctuate, while electricity is generally a more predictable cost. Average costs per year (after losing some AFUE through ducts):

      • Propane: $1,550
      • Natural gas: $850
      • Electric: $900
      • Oil: $820

Average heating costs per year depend on market prices for natural gas and oil, but it has a few unique cost-saving factors:

      • Doesn’t lose AFUE in ducts.
      • Can use zone heating, which reduces energy waste.
      • Costs can be even lower if you install an eco-friendly boiler.
      • The costs of heating your home are closely tied to how much it costs to heat the water tank. As you need more heat, more water and energy are required to keep your home warm. Here are the average annual water heating costs for a cold, northern climate.
        • Propane: $630
        • Oil: $500
        • Natural Gas: $240
        • Electric: $500
Lowest Price to Run: Boilers

Location & Local Climate

Which one would work better in your location?

      • Newer models can be up to 98% efficient in heating a home, but they lose up to 35% efficiency in air ducts. In very cold climates, homes can feel a bit drafty and dry because the heat distribution isn’t consistent.

      • High-efficiency models are up to 90% efficient without losing any heat in ducts. They heat homes through radiant heating that keeps the home evenly warm with more humid indoor air.

The winner in Texas & Florida (south): Furnace with A/C
The winner in Washington State (west): Boiler
The winner in New York (north): Boiler

Space in Home

Define how much space does each unit require? Which is better for structures like barns or detached garages?

      • They’ll need a spot in your basement, crawl space, or mechanical room. Outdoor units are ideal for separate spaces that don’t have ducts since they can send heat directly through walls.

      • Though the hot water tanks take up space in the home, some combo units don’t require tanks. They don’t need ducts because they use radiant-style heating. Boilers can also be outdoors.

The winner: Tie, since both can be outdoor units

DIY & Installation


      • DIY considerations: Installing it requires knowledge and experience. This is especially true if you need to connect your unit to gas lines or oil tanks. It’s recommended that you hire a pro given the many safety pitfalls of a DIY job.
      • Average professional costs to install a furnace vary by energy type.
        • Electric: $1,950
        • Gas: $2,370
        • Oil: $5,780
      • Installation takes just a few hours.
      • DIY considerations: Handling gas lines and oil tanks always involves risk. Also, electric-powered units have their own risk of electrocution during installation. This can be avoided when a knowledgeable professional takes the helm.
      • Professional costs to install range between $3,400 and $7,400, with the average installation cost of $5,300.
      • It usually takes 3-4 days to install this complex system.
Cheapest to Install Furnace

Tune-Ups & Repairs

Which system is more affordable to repair?

Home furnace air filter replacement

Cheapest to Repair or Service Furnace

Maintenance & Cleaning

Which system is easier to maintain and clean throughout the year?


  • These models don’t have ducts or air filters, which leaves less to maintain and clean.
  • Getting a yearly inspection is also highly recommended to prevent expensive fixes.

Easiest to Maintain Boiler


Which model is safer for your family, pets, and home?


  • Properly installed units are backed with safety measures. For example, gas units have protection against fumes and combustion issues.


  • Homeowners must maintain their furnaces regularly to keep all safety measures working properly.
  • With gas furnaces, there’s a risk of carbon monoxide if these measures fail.
  • Family members with allergies will react more to the dryness and dust from forced air units. However, installing a humidifier can remedy the dryness issue.


  • They’re better for people with allergies because they deliver cleaner air (no dusty ducts).
  • The air is more humid compared to forced air units.


  • Electricity and water don’t mix, so any malfunctions with electric units need attention ASAP.
  • It can also leak water which can lead to mold and damage to your property.

The safer and healthier option Boiler

ROI & Resale Value

The right unit will have a positive impact on your home’s value. Which one is a better investment?

  • They cost less per unit and can last 15-30 years. Newer models are more energy efficient which is attractive to homebuyers.

  • They cost more per unit and can also last 15-30 years. However, there are quite a few known to last for decades and even over a century. Newer models are becoming more energy efficient, which homebuyers like.

Best for Resale Boiler

Industrial Units for Commercial Use

Which model is better for large commercial spaces?

industrial boiler tank and large pipe top of hospital building.

  • Though their presence isn’t common in commercial buildings, newer models are coming out that can efficiently heat larger spaces.

  • These are more common in commercial settings because they can heat large spaces for less.

Best for Resale Boiler
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Combo Units

Sometimes your home needs a unit with a unique set of capabilities. In this case, a combo unit may be the best option for you.

Hot Water Furnaces

Though you may see this term floating around the internet, be advised that this is just another name for a steam or boiler heating system.

Forced Air Boilers

These are properly known as hydro-air systems, which is a hydronic heating system combined with the power of forced air. In this system, an oil or gas hot water boiler heats water, which is then is transferred to a coil in an air handling unit. A blower then sends air over the hot coils to push warm air into your ducts. The perk of this system is that the air isn’t as dry as with a forced air heating system.

Combi Boilers

These units, which are often called “combis”, are a combination of a water heater and radiant heat. They’re common in homes and apartments less than 1,500 square feet. They don’t require a storage tank but instead get water from the main. As a result, you get hot water and heat whenever you need it. There’s also no wait time for your tank to heat up.

Which System is Better for Your Home?


  • More affordable unit price
  • Affordable professional installation
  • Low repair costs
  • Quicker & easier installation
  • Can take up minimal space
  • Best for temperate and southern climates (paired with AC)


  • Higher ROI/Resale value
  • Safest
  • Lower utility payments
  • Easier to maintain
  • Cleanest
  • Can take up minimal space
  • Best for commercial/industrial use
  • Best for cold/northern climates

Which System do you Have?

The easiest way to tell is to look at your system’s label. What does it say? If it’s still hard to discern, then get a professional to inspect it. Is hot air being forced through vents with blowers? If so, you have a furnace or combo system. If the heat is being sent through pipes and heating your floors, walls, or baseboards through radiant heat, it’s likely a boiler.

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Other HVAC Systems

Boiler versus Furnace versus AC

As opposed to furnaces and boilers, air conditioners can only cool and dehumidify the air. They use a compressor to draw air into a condenser, which liquefies the air, sending it into a thermal expansion valve that then gets sent into controlled amounts into the evaporator coil, where it’s used to cool down air that a fan sends into vents.

Learn more about the differences between heat pumps and air conditioners.

Heat Pumps

Heat pumps can serve as both a heating and cooling unit and are best suited for temperate climates with mild winters. They don’t require a pilot light or combustion. They also don’t heat the home through water or pipes. Instead, heat pumps draw heat from the ground or air and convert it to hot or cold air depending on the cycle that’s activated. To learn more, explore the differences of a Heat Pump vs. Furnace.

Convection Baseboards

Convection baseboards are not to be confused with radiant baseboards. These electricity-powered units are not very efficient and are only suited for small spaces where great heating power isn’t required. It sends little heat into the room without a blower.

Best Brands & Models


  • Trane
  • Lennox
  • American Standard
  • Carrier
  • York
  • Goodman


  • Slant-fin
  • Bosch
  • Westinghouse
  • Lennox
  • Crown

Combo Units

  • Navien
  • Bosch
  • AO Smith
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  1. Mike, May 21:

    The efficiency numbers are very outdated. Modern gas fired furnaces can be > 98% AFUE. Same with gas fired boilers.

    A furnace can actually be healthier than a boiler since it can constantly recycle and filter the air in the house.

    In my experience, on average boilers are similarly priced and have a similar time and complexity to install as furnaces. Usually 1-2 days for both.

    Honestly under DIY it should just say don’t do it, period. These are not DIY projects. Additionally there is a lot more to consider, such as correctly sizing the equipment for the house and its pipes/ducts if they are already present. It is more often than not incorrect to simply replace equipment with new equipment of the same size.

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