Furnace, Boiler, or Stove: What’s the Difference?

Thermodynamically, furnaces, boilers, and stoves share minimal differences. Here’s a concise overview:

• Furnaces heat air, which is circulated through the house using a fan and ductwork.
• Boilers heat water, distributing it via pipes to radiators that warm the rooms.
• Stoves serve as centralized heat sources, often resembling fireplaces. They may have fans but typically have limited heat distribution capabilities.

While each type has its pros and cons, their costs and emissions are generally comparable, with efficiencies varying by only 10–20%. I will refer to these collectively as "traditional heating."

What Makes Electric Heaters Unique?

The most significant aspect is that electricity can potentially offer emissions-free heating. Traditional combustion heaters rely on fuels such as natural gas, propane, or wood, producing heat through combustion. This process can lead to inefficiencies and health risks due to exhaust needing to be vented outside.

Electric heating is ubiquitous in our lives—think toasters, electric stoves, space heaters, and more—operating on similar principles, albeit at a larger scale. Traditional electric heaters utilize resistive heating, where an electrical current flows through a resistor, converting electricity into heat.

Resistive heaters boast 100% efficiency and do not require exhaust systems. Their versatility and simplicity make them common in affordable housing.

Is Resistive Heating Cost-Effective?

Unfortunately, the answer is no. Currently, traditional electric heaters tend to be more expensive and often produce a larger carbon footprint.

Video Description: Discover insights about transitioning from gas to electric heating and the key considerations to keep in mind.

As most electricity is still generated from fossil fuels, your electric boiler may be powered by methane, similar to a gas boiler, just via a power plant. The conversion process from methane to electricity is only about 20% efficient, inflating both costs and emissions.

While electric heating has the potential for emissions-free operation, achieving this requires additional effort on your part. Depending on your location and energy payment structure, your electricity may already be significantly cleaner than indicated.

The electric grid is becoming greener, with initiatives underway to decarbonize various regions. You could even consider rooftop solar installations for your own clean energy or opt for zero-emissions energy plans that may be more affordable than standard fossil fuel electricity. In my case, this was true.

Creating a zero-emissions electric grid is complex and requires collective action from consumers, utilities, and government oversight.

Are Heat Pumps a Better Option?

Interestingly, heat pumps (HP) offer a solution that exceeds 100% efficiency. Rather than generating heat, they transfer it from outside to inside. In optimal conditions, an efficient HP can move 3 kWh of heat into a home using only 1 kWh of electricity.

Heat pumps function similarly to air conditioners, making them an excellent option if you can install one.

Efficiency can vary significantly based on numerous factors, some of which you can control (like indoor temperature) and others that are out of your hands (like outdoor conditions). Every home is unique, and I can’t predict how your heat pump will perform.

For instance, while some users successfully operate their heat pumps at temperatures as low as 5°F (-15°C), mine struggles below 25°F (-4°C), necessitating the use of a backup furnace.

A dual-source system, which combines a heat pump with traditional heating methods, can effectively provide comfort year-round. The HP can cool your home in summer and heat it during milder winters, switching to traditional heat for extreme cold.

Comparing Costs: Heat Pumps vs. Traditional Sources

The efficiency of a heat pump diminishes in extremely cold conditions, but it still outperforms other heating methods in terms of emissions.

While gas furnaces and wood can be cheaper at very low temperatures, a heat pump's overall emissions remain significantly lower.

What Are the Costs of Emission-Free Heating?

In my case, the heat pump accounted for approximately 60% of my heating last year, reducing emissions by over a ton compared to using gas alone and saving about $100 on heating costs.

Continual monitoring and adjustments are crucial to understanding the financial impact of switching to a heat pump. Anticipate a follow-up article in spring as I compile more data.

To achieve zero emissions, I would need to replace my furnace with a resistive heater, which would nearly double my costs annually.

Is It Time to Go All-Electric?

For now, I am keeping my gas furnace, as it still has many years of service left. However, there are substantial opportunities to electrify and save on costs.

If you’re considering replacing or installing a new air conditioning system, opting for a heat pump is a wise choice with no significant downsides. Subsidies and savings on heating costs can help offset the higher installation expenses.

For many homes, a heat pump may eliminate the need for any additional heating sources. However, for homes like mine, where the heat pump is insufficient during the coldest periods, going entirely electric remains a challenge.

Resistive heating can be beneficial in specific scenarios, such as for those committed to a zero-emissions lifestyle or homes with excess solar energy.

For the majority, home heating will lean towards electrification, reducing emissions but not completely eliminating them.

The primary barrier remains the cost of electricity. As we enhance infrastructure to clean the grid, it’s likely that the price per kWh will increase to fund this transition.

While I hesitate to suggest a carbon tax on heating fuels, as it could impact affordability, a commitment to reducing emissions necessitates cleaning our electricity supply and making electric heating costs competitive with traditional high-carbon options.

Video Description: Explore whether it's more economical to leave your heating on continuously, examining the implications for energy consumption and costs.