Boilers and Furnaces - What is the Difference?

Boilers and furnaces are the main tools for home heating. When you next plan on renewing the heating for your retrofit or new home, there are some key differences between boilers and furnaces that you should know.

Basically, boilers and furnaces warm your home. However, they do it in very different ways. A boiler is a hydronic system that uses pipes to carry heated water to the rooms within your home. A furnace pushes the heated air through a series of ducts to distribute warmth around your home. So, in a nutshell, one is a dry system while the other is a wet system.

To understand the key advantages and disadvantages, first, we should look in more detail at boilers and furnaces to get a handle on what they do.

What Is a Boiler?

A boiler heats water in a holding tank and circulates it around your home via radiators, baseboard heaters, or underfloor heating coils. The boiler is typically located in a central location and uses a series of pipes that emanate outwards to all the rooms in the house.

How Does a Boiler Distribute Heat?

Try and imagine a boiler as a beating heart and the pipes as arteries, supplying heat to different spaces within the house. The boiler generates hot water or steam, depending on the water dispersal system you have. This heat is then pushed through either radiators, baseboard heaters, or coil systems under the floor to increase the room temperature.

How Is a Boiler Powered?

Boilers use lots of different energy sources to create heated water. Most use either natural gas, oil, or electricity, but some even use wood to generate warmth.

How Many Types of Boiler Are There?

With the advancement of technology, there are an ever-increasing variety of boilers available to buy. Each has pros and cons, with some suiting different settings better than others. Here’s a handy list of the types of boiler you can buy.

Condensing Boiler

Condensing boilers are more efficient than non-condensing models because they are sealed systems that capture flue gasses that would have been lost in other systems. It makes them one of the most efficient boilers you can buy. Condensing boilers are more energy-efficient, harnessing 90 to 92 percent of the energy and transferring it to heat.

Non-Condensing Boiler

Non-condensing boilers are the older, more established models. They have been around for generations, providing reliable heating in our homes. However, with the move towards greener and more frugal forms of heating, non-condensing boilers have lost a lot of ground to their condensing counterparts.

These types of boilers are not sealed systems, so wastage is greater, reducing the energy-extraction levels to between 50 and 80 percent.

Gas Boilers

Gas boilers are the most common, especially in more urban areas. They are also cheaper to run than electric boilers. While a gas boiler is not 100 percent efficient compared to an electric radiator, you get more heat for your dollars because it is cheaper.

While gas is not environmentally friendly, it is the greenest of the fossil fuel options. Gas creates less than half the CO2 emissions of oil and a third of coal.

Oil Boilers

Oil boilers are a great option if you live without a natural gas supply. They are commonly used in rural locations where off-grid living is the norm. The advantage is you can get a continuous source of warmth throughout the winter months.

The downside is you need to get the oil delivered, and it fluctuates in price. You also need a large holding tank to hold the reserves of oil.

Propane Gas Boilers

These boilers are another great alternative to natural gas boilers, especially if you live off-grid in remote areas. They work along the same lines as a gas boiler, except the gas comes from large canisters stored outside the property.

Electric Boilers

Electric boilers are cleaner than other types because they do not produce waste exhaust gases. They are also more efficient. However, it will cost you 3 to 4 times the amount to run an electric boiler compared to a natural gas version.

Electric boilers are common in high-rise apartment blocks where gas is a fire risk, and as a result, there is no gas available in the building. The main advantage of these boiler types is they are smaller, quieter, and cheaper to buy and install.

The disadvantage is they are not suitable for larger homes, as they struggle to provide the heat required and the high cost of electricity.

Biomass Boilers

Biomass boilers burn wood chips or pellets to heat a holding tank full of water, which is then transferred to the inside of your home. These boilers are environmentally-friendly because, in the case of wood, they releases as much carbon when burned as the wood absorbed when it was a tree,

Biomass boilers free you from natural gas, meaning as long as you remember to order the pellets, you can use them anywhere. They are another excellent off-grid option.

The downside is they are expensive to buy and install. Plus, you also have to create space to store the pellets.

The Pros of a Boiler

  • Reduces dust and allergens within the heating system.
  • Quieter operation.
  • Provides a more balanced heat source.
  • Underfloor heating is the most comfortable distribution.
  • Piping is more versatile than ducting.

The Cons of a Boiler

  • Single-use system. Additional AC is needed for cool air.
  • Water leakage causes more damage to your property.

What Is a Furnace?

A furnace uses combustion to generate hot air, which it then pumps throughout your home using ducting in the floor, walls, or ceiling.

How Does a Furnace Distribute Heat?

The hot air generated from the combustion process gets pushed through ducting via a heat pump, blower, or fan. In each room, vents or registers allow this hot air to enter the room. Because the ducting fits inside walls, floors, and ceilings, these vents are typically found in the walls or floors.

It’s worth remembering that if you compare the performance of furnaces and boilers, furnaces are less efficient distributers because water retains heat much better than air.

How Is a Furnace powered?

A furnace can operate using natural gas, oil, propane, and electricity. Some older homes have coal furnaces located in the basement, but thankfully, modern homes rarely employ this system because it is dirty and takes up a lot of space.

How Many Types of Furnaces Are there?

Essentially, there are 4 main types of furnaces available for domestic heating.

Natural Gas Furnace

Natural gas furnaces are the most popular type available. They are cheaper to run than electric varieties, and you have a continuous supply of heat. These furnaces are also incredibly efficient compared to other fuel types.

A natural gas furnace returns a 98 percent efficiency in the newest models. That is just 2 percent wastage, making it a cost-effective heating method.

Oil Furnaces

Oil furnaces are less efficient than natural gas systems. They can reach 80 to 90 percent efficiency, so they are still a good option for returning on your investment. They are also one of the best choices for remote locations without a  gas supply.

Oil furnaces are most popular in the Northeastern USA.

Propane Furnaces

About 10 percent of furnaces use this energy source. Propane is a by-product of natural gas and oil production and gets stored in large tanks located outside the home. Propane is another remote location heating option.

The only downside with propane is you have to remember to keep on top of your reserves.

Electric Furnaces

Buying an electric furnace is a lot cheaper than the other options and they are easier to install. They also return the highest values when it comes to energy-efficiency, and the longest lifespan.

However, electricity is expensive compared to other energy sources, which dramatically increases your monthly running costs.

Electric furnaces are not as powerful as gas or oil options, so you might have to rethink if you have a larger home.

The Pros of a Furnace

  • Lower leakage hazard.
  • Dry system.
  • Ducting is less costly.
  • Easier to service and repair.

The Cons of a Furnace

  • Less efficient.
  • Larger energy consumption.
  • Dry systems contain dust and allergens.
  • Filters required.

Boilers and Furnaces - The Decision is Yours

So, now you know the difference between boilers and furnaces, it’s up to you to decide which system is better for your home. There are more options with a boiler, and you also get greener alternatives like biomass systems. Plus, water retains heat more efficiently than air

Furnaces do have their advantages though. With a furnace, you can incorporate the installation as part of a complete central heating and air conditioning system. You don't have to have two separate home networks (e.g. - radiators and air ducts) for your comfort. You can instead use a furnace on a central air system for simplified heating and cooling.

Don't know how to choose between boilers and furnaces? You can check out our great selection of furnaces here, and our amazing inventory of boilers right here.

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