A Case for Replacing your Furnace (and Air Conditioner) with a Heat Pump
By Ellen Rubin
Climate change is a fact of our lives. Winters are colder, summers are hotter. The cost of fossil fuels and the amount of pollution are increasing while our incomes and natural resources are decreasing.
New challenges call for new solutions or at least rethinking the effectiveness of how we’ve done things in the past. Heat pumps are a newer way to rethink our HVAC needs.
The Cost of Comfort
Traditionally, buildings have a furnace in the basement or utility room that is powered by natural gas, oil, propane, or sometimes electricity, and a separate air conditioning unit that sits outside and is powered by electricity. This matters because buildings account for 20-30% of all greenhouse gas emissions in the US and heating, cooling, and water heating account for half of the energy used.
Monetarily, the average cost of running a furnace through winter is $850 for gas, $900 for electric, and $1550 for propane fuel. The average cost of using a heat pump powered by electricity is $500.
Of course, cost is dependent on the volatile price of fuel, average temperature, and the age and efficiency of the system. In comparing heat pumps to furnaces we’ll talk about the advantages and disadvantages of installing a heat pump.
What is a Heat Pump and How Does It Work?
Furnaces heat by burning fuel of some sort to generate heat that is then blown through ducts throughout the house.
Air conditioners and heat pumps work on a different principle. Instead of generating energy by burning fuel, they work by transferring heat. (Please forgive any mechanical inaccuracies, I’m not a HVAC specialist.) Heat pumps blow air over a heat exchange surface that causes a liquid refrigerant with a very low boiling point to turn into a gas. The gas moves through a compressor which increases the pressure and causes its temperature to rise.
The heated refrigerant gas is passed over an internal heat exchange surface to warm air (or cool in the summer) and that is then blown around the home’s interior. Once all the heat has been transferred, the temperature of the gas decreases and it returns to its liquid state.
Heat pumps have an outside compressor, evaporative coils, and a fan. There is a separate indoor unit called an air handler that houses more condensing coils and another fan. The two units are connected by a hose between them. In summer, the heat from the interior is transferred to the outside.
Heat Pump Advantages
Heat pumps have clear environmental, monetary, safety, and comfort advantages. This is why their popularity has grown as more people become aware of their potential. The Air Conditioning, Heating, and Refrigeration Institute reports that they were 21% more popular than gas-powered furnaces last year.
Their 2023 market share grew 2% to claim 54.7% of the market. It’s hard to decide what’s more important: improved air quality and comfort, energy savings, or environmental sustainability. They can all factor into your decision-making process because they are all important.
Air Quality
Because heat pumps don’t burn fossil fuels they don’t produce harmful emissions – both in your home and into the environment. Furnaces release the combustion gases through a flue, usually in your roof. They also leak gases, including carbon monoxide, carbon dioxide, and methane, into your home. Between 2010 and 2015 2,244 Americans died from unintentional carbon monoxide poisoning because of incompletely burned fossil fuels.
The Consumer Product Safety Commission has traced an upward trend in non-fire carbon monoxide poisoning deaths. Heat Pumps eliminate this problem because neither carbon monoxide nor methane are created.
Furnaces also release fine particulates (less than 2.5 microns in size) into the air within and around the building when fuel is burned. This size particulate can pass directly into our bloodstream from our lungs as we inhale, and accumulate in all our organs. Furnaces have filters to help mitigate the danger. Gas fired furnaces produce 45% to 70% more emissions than heat pumps.
Heat Pumps don’t actually bring in outside air to heat your home – merely transfer heat. That means that filters within your home and in heat pumps can be more effective. If you live in an area that is affected by wildfire smoke or heavy pollution, this is an added bonus. Yes, there are filters in heat pumps, just as there are on furnaces, to improve indoor air quality.
Many furnaces recommend changing filters monthly and heat pumps recommend every 1-3 months depending on household factors and the type of filter. Some heat pumps even come with washable or reusable filters, such as electrostatic filters.
Efficiency
Burning fossil fuels isn’t efficient and most systems consume 50% more energy than they produce. That is just wasteful. According to the International Energy Agency heat pumps are 3-5 times more energy efficient than traditional heating and cooling systems. Geothermal heat pumps are the most efficient at 70-80% efficiency, however, they aren’t practical in every setting.
Generally, with research and design improvements, efficiency is only going to improve. Researchers at Eastern Switzerland University of Applied Science, have been fine-tuning a blend of refrigerants that increases performance by up to 25%.
Having a system that reduces your energy costs, for both heating and cooling, is certainly something to consider. If you currently use electric baseboard heaters and furnaces, your energy savings should be 65%. Plus, heat pumps pair extremely well with solar panel use. What’s not to like about slashing energy bills and pollution at the same time.
Home Comfort
By transferring heat, rather than burning fuel, you aren’t drying out the air in your home so you may not need to add a humidifier to lessen static shocks and dry skin. Heat pumps tend to run longer, yet less frequently, than furnaces so you don’t have the rush of warm air and then cooling; thereby maintaining a more consistent temperature throughout the day and improved air circulation.
Sustainability
You might wonder if trading out gas powered HVAC for electric is truly more sustainable. After all, the energy to run the system comes from somewhere. Power companies are increasingly turning away from fossil fuels and embracing renewable sources of energy.
Even the US, which is not among the leaders, uses over 20% non-fossil-fuel sources. Depending on your location, that proportion is significantly higher. For instance, Northwestern Energy in Montana gets 58% of their electric generation from carbon-free sources and 40% of the energy in South Dakota comes from wind projects. Some countries get 100% of their electricity production from renewable sources.
Here is a listing by country: List of countries by renewable electricity production – Wikipedia. Both very warm African countries and cold Scandinavian countries have found a way to use 100%, or almost 100%, renewable energy, making it easy to avoid gas-sourced heat in favor of more monetarily stable electricity.
Size
If space is an issue, you might want to consider a heat pump. The outside unit requires less clearance than a traditional air conditioner – only 24”. The indoor unit takes up even less space. Both can be wall-mounted. Usually, furnaces are bulky and require a separate room or dedicated space in a basement, crawl space, or utility room. Attached humidifiers take up additional space.
Addressing and Debunking Typical Arguments Against Heat Pumps
Cold Weather Function
One of the most frequent arguments against heat pumps is that they don’t function well in cold weather. While this might once have been valid, today’s models function well in -30°F weather. The refrigerant can be between -15° and -56°F so any air temperature above that will allow air to turn to vapor. High performance heat pumps are twice as efficient as natural gas heating systems in sub-zero weather.
While it’s easy to read statistics and company claims, real-world proof is aways reassuring. Maine, one of the coldest states, surpassed their goal of having 100,000 residences install heat pumps by 2025, a year and a half early. The new goal is 175,000 residences by 2027. (There are only 570,000 households in Maine and that figure includes those living in multi-family dwellings.) Overall, the state had a 10% decrease in heating oil as the primary fuel for heating from 2018 to 2022. In Norway, Finland, and Sweden over ½ of the homes use heat pumps.
Longevity, Maintenance, and Cost
It’s true that furnaces have a slightly longer useful life than heat pumps: 20 years vs. 15 years. Note that heat pumps longevity may be negatively impacted if you live on a salt-water coast. Both systems require regular maintenance and filter changes so I don’t know that maintenance for one system is more economical than the other.
Another argument is that the initial cost of a heat pump is slightly higher than a non-high-efficiency furnace. This is a multi-part issue and you would need to do your own research into how much each system would cost to purchase and run where you live. However, these are some of the factors you should consider:
- Unit cost. A new furnace generally costs between $2,800 and $9,500 for a high-efficiency model. High efficiency models don’t require an outdoor flue because they recycle combustible gases but they need a PVC drain pipe to discard the acidified water they expel. Heat pumps have a slightly higher initial cost of $4,200 – $6800. Two factors help mitigate the manufacturers cost of heat pumps. There are a lot of rebates available, including those offered by the US Inflation Reduction Act. Investigate what incentives your local, state, or national governments offer. Also remember that heat pumps act as a cooling unit so you don’t have to purchase separate air conditioners.
- Running cost: Electric heat pumps cost about ½ as much to run as natural gas or electric furnaces, and as little as 1/3 as much as an oil or propane furnace. Installation costs are similar among all options. The Canadian Climate Institute has found that heat pumps were the least expensive option, between purchase and running, about 67% of the time.
Noise Level
There are some claims that heat pumps are noisier than furnace options. Most of the noise comes from the compressor, which in the case of heat pumps, is located outside. Heat pumps make clicking or knocking sounds rather than the whoosh and blowing sound you hear with a gas furnace. Having a humidifier attached to your furnace increases the noise. Some heat pump owners claim that their units are quieter than their previous furnaces. If noise levels are a concern for you, compare manufacturer’s information on available models.
Alternative Solutions using Heat Pump Technology
There are some heat pumps that use an underground network of pipes filled with a mixture of water, antifreeze, and/or a refrigerant placed below the frost line, to generate the heat. The piping acts as a heat exchanger, absorbing the earth’s heat. The rest functions like a standard heat pump. This system takes advantage of geothermal energy and is an effective way to generate a greater amount of heat.
Germany has taken advantage of large community heat pumps. Currently district heating stations supply heat for 15% of the buildings. Their goal is to have 70% of the country run on thermal energy from wastewater, industrial waste heat, and geothermal energy by 2024 instead of using coal, oil, and natural gas.
If you are unable to install a heat pump where you live, possibly because you are renting or in an apartment, there are still some options besides traditional furnaces.
Mini-splits are smaller units that can be installed to heat/cool a particular room. They don’t require conduit ducts, but function more as single room installations. For more information on their requirements see Mini Split Power Requirements – PICKHVAC.
Another option are units marketed as portable air conditioners/space heaters. They need minimal installation and can be moved from room to room. They do require exhaust hose(s) that vent to an outside window. These are fairly efficient, consuming roughly a third of the energy used by natural gas heaters, and have the added advantage of filtering dust, bacteria, and viruses from the air. They run on regular household electricity.
If you want to learn more, you can find information on these, and even mini-split systems, on Amazon. Still, your best choice is to replace your air conditioner and furnace with a home heat pump.
There are a few companies that are developing window-mounted heat pumps. These aren’t commercially available yet, but probably will be in the near future. They don’t require significant space, and can be set in vertically sliding windows.
Heat pump technology can also be used to power your water heater rather than relying on electricity or natural gas. Using one significantly reduces the 20% of home energy that is typically spent to heat water. It also reduces the overall use of natural gas, a non-renewable resource, makes you less dependent on volatile pricing, and eliminates another common source of carbon monoxide poisoning.
Heat pumps have many advantages for your comfort, health, the environment, and your pocketbook. Luckily, they are becoming more known and widely used. States are starting to encourage their purchase through incentive programs; 9 US states have pledged to boost sales to 65% of the HVAC market in the next year and to 90% by 2040.
The US Environmental Protection Agency has just awarded $450 million to Maine, Connecticut, Massachusetts, New Hampshire, and Rhode Island to accelerate heat pump sales. California is considering a ban on the sale of gas furnaces for environmental reasons. 25 states are part of the US Climate Alliance that promotes policies to speed up the installation of heat pumps to quadruple their current number. These states represent 54% of the population and 57% of the economy.
While 4.7 million heat pumps have already been installed in the US, the goal is to reach 20 million by 2029. See 25 States Agree To Quadruple Number Of Heat Pumps In America – CleanTechnica for more information.
As demand grows, more companies are starting to enter the market with planet-friendly designs and engineering. Johnson Controls has developed the first commercial heat pump that uses a refrigerant with lower “global warming potential” than other types, making it even more sustainable. The unit produces 4 units of heating power for each unit of power input.
Final Thoughts…
The greatest advantages of heat pumps are that they save consumers money while also creating a safer, more comfortable home and protecting the environment. While those who have interests in fossil fuel production may not think this is a worthwhile endeavor, with more countries switching from fossil fuel dependence to renewable energy for their power grids, switching your home heating from gas-based to electric makes a lot of sense.
If you want to know just how far the acceptance of heat pumps has come, here is a musical tribute to them: Musicians’ Slow Jam Is Ode To Heat Pumps – Videos from The Weather Channel
Companies Manufacturing Heat Pumps
Bosch, Daikin, Johnson Controls, and Midea all participate in the Residential Cold Climate Heat Pump Technology Challenge.
Some popular HVAC companies that offer heat pumps options include: Carrier, Lennox International, Rheem, and Trane Technologies.