Understanding the Differences Between Furnaces and Boilers

Understanding the differences between Furnaces and Boilers

What type of heating system is best for you and your house?

We often receive calls from our customers asking about the differences between furnace and boilers. They oftentimes use the word “boiler” when they actually mean “furnace”. People just don’t understand what their differences are.

To arrive at a better choice, you must get to know first the difference between furnaces and boilers. People frequently refer boilers and furnaces the same, although they are not. 

In this blog post, you will know the differences between boilers and furnaces, how they work, the pros and cons of each system, and the things to consider in choosing the best heating system.

Outdoor Boiler and Furnace: What’s the difference?

The simplest way to remember the difference is that an outdoor furnace uses air and an outdoor boiler uses water in distributing heat throughout your home. 

A furnace heats with the air so it has a heating element inside of it. It heats air and then it distributes the heat through ductwork.


A boiler heats with water and that’s most of the outdoor wood boilers, they are considered outdoor wood boilers however people call them outdoor wood furnaces. They distribute the heat through piping or pipe. (Click here to see the BEST PEX Pipe for your outdoor wood boiler.) And the way that distributes the heat throughout the house is through usually baseboards, air handler, or even radiant floor heating.


What are the pros and cons of each system?

Outdoor Wood Boilers and Furnaces has been keeping families toasty warm for decades already. But now more than ever, using outdoor wood boilers is beyond question the best alternative for heating American homes as the price of electricity and natural gas is unceasingly rising. But...

Your choice of an existing heating system in your home may be influenced by weighing the benefits and drawbacks of each system. 

Warm air from furnaces causes a drafty environment because air is constantly moving in all directions. While air movement is fantastic for cooling in the summer, it is uncomfortable for heating. Baseboard or cast iron radiators, which use convection or radiation to heat the air, will deliver consistent, dependable heat.

In contrast to forced air heating systems, hydronic heating won't dry out the air or distribute dust and allergies throughout your house. If you attach the furnace to the air conditioning ductwork to heat it will be less expensive than using a boiler system for heat and central air cooling. Domestic hot water heating is more comfortable. 

No matter if you have a boiler or a furnace, if you don't maintain it, it won't run as efficiently as it should. And since you may be heating your home less effectively, you could be losing money due to this heating cost.

The type of maintenance needed for these systems is another distinction. Some contractors advise changing the filter of a furnace anywhere from once a month to once a quarter for best air quality because the air is blown throughout the house. Outside wood boilers require entirely separate upkeep. An efficient outdoor wood stove can last for years with little maintenance, unlike high-efficiency boilers and oil boilers (such as a warm air furnace).

Filter Kit

How Efficient are Outdoor Wood Boilers?

Outdoor wood furnace efficiency ratings are measured in many ways and this can be deceptive. Some rating methods are hard to understand. Most commonly, “efficiency” is measured based on “What percent of BTUs in the fuel goes into your building?” With all fuels, some of the heat from the fuel must go up the chimney to eliminate contaminants, but this “lost heat” needs to be minimized. If 100,000 BTUs of wood fuel is put into an outdoor furnace, and 80,000 BTUs of heat are sent to the home, then that outdoor furnace efficiency can be rated at 80%. Most of the high-efficiency outdoor boilers achieve 80% or more efficiency.

How to Make Your Outdoor Wood Boilers more efficient?

The quality of woods you burn will affect the efficiency of your outdoor furnace. The energy stored in various types of wood can vary significantly. Also, another factor that affects the available heating BTUs in your wood is its moisture content. ​Freshly cut green wood contains up to 50% moisture. That means that 50% of the weight of the wood is water.

When you try to burn green wood, you must first use up your precious BTUs from your fire to boil off the water in greenwood. Those are BTUs that could have gone into your home but instead are wasted. But properly seasoned wood contains only 20% moisture.

So the 3 Most Important Steps are as follows:

  1. Split
  2. Stack
  3. Cover

    Click here to know more about these three important steps.

    What are the things to consider in choosing the best heating system for your home?

    1. Boilers provide more flexible installation options because it is simple to transfer a lot of heat through a small number of pipes. Although furnaces can be built in remote areas, boilers cannot because the air cools down too quickly as it moves, and it is difficult to move over long distances.
    2. Air does not retain heat as well as water does. Additionally, air does not transfer heat as quickly as water. Therefore, boilers frequently outperform furnaces in terms of efficiency. Large fans require more energy than circulators, which are designed to circulate hot water, in order to move air.
    3. In order to store water at low pressure, boilers are typically made with heavier materials and more intricate construction. Furnaces typically have simpler construction methods and lighter materials. Furnaces typically cost less due to these factors.
    4. Due to the fact that hot water heating does not significantly dry up the air in winter, many people find it to be more comfortable than hot air heating. Dust and grime in the air can also be stirred up by air heat. Using the same ducts in furnaces can help transmit heated air in the winter and can also move cooled air in the summer.
    5. In general, water-cooled engines last longer than air-cooled ones because of this. Outdoor wood furnaces warp or break significantly more quickly than outdoor wood boilers because they are more difficult to shield from heat.

    It is important to understand the functions of the furnaces and boilers so you can ensure that you're doing everything to keep your home operating effectively even though you're not giving enough attention to them when they are running smoothly.

    If there is a question that you cannot get an answer to, just contact us! Let us know your question - we are here to help you! Simply click HERE to ask us any question. This time of year is very busy so please forgive us for being swamped, but we value you as our customers and want to help you. (Note: Urgent calls get the highest priority.)