Space heating is the largest energy consumer in our houses, accounting for around 45% of the average household energy bill in the US. Therefore, the efficiency of your furnace plays a major role in how much money you save or lose each month.
A 95% AFUE furnace costs on average $750 – $1,000 more than a similar size 80% AFUE furnace, so the payback periods for them may be quite long if it is not used to its full potential.
Use our new Furnace Price Calculator to estimate HEATING BTU LOAD for your home, and cost of installing new 80%, 95% and 97% AFUE furnace.
Taking into account the price difference between the standard and a high efficiency furnace, is it always smart to purchase a more expensive high-efficiency furnace?
Lets look into this question by exploring different scenarios, as well as reviewing the top 7 high-efficiency gas and oil-fired furnaces on the market.
If you are ready to replace your furnace, call your local HVAC pros to get quotes and compare prices.
How does a furnace work?
The furnace operates on the principle of forced air heating and can be fueled by oil, natural gas, propane, wood or electricity. In simple terms, the furnace transfers the heat, generated from burning fuel, to the air, which is circulated around the house by the fan through the ductwork system.
Going down to details, the pilot light ignites the burners inside the combustion chamber, and the created heat enters the heat exchanger.
There, the heat is transferred to the air and raises its temperature to the one set by thermostat. The blowers push the warm air into the occupied space through supply ducts and suck the cool air back in via return ducts.
This type of furnace is called “standard” or “non-condensing”. For a detailed illustration of various components refer to the figure below.
When replacing your heating system, one alternative to consider is a boiler. Here is a detailed break down of all the pros and cons of a furnace vs a boiler.
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Low End
$3,300 - $3,900
Mid Range
$4,000 - $4,500
High Efficiency
$4,500 - $5,200
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See costs in your area
What is a high-efficiency furnace?
All high-efficiency furnaces are of condensing type and utilize a second heat exchanger to capture the extra heat from the condensed exhaust gases. The secondary heat exchanger pre-heats the incoming cool air, which significantly reduces fuel consumption.
Typical Condensing Furnace Components:
Understanding furnace efficiency
The efficiency of a furnace is measured by the Annual Fuel Utilization Efficiency (AFUE). It represents the ratio of annual heat output compared to the consumed fossil fuel energy.
For instance, if a furnace is 95% efficient, it means that 95% is converted to useful heat for your house and 5% is lost through the walls of the furnace and via exhaust gases through the chimney.
Note, however, that there are further loses of heat through the ductwork, especially if it is not insulated and is running through non-conditioned places such as attic and garage. These loses are not included in the AFUE value.
Did you know? An all-electric furnace does not generate flue gases and, therefore, does not have the heat loses associated with that. The efficiency of such boilers is between 95% to 100%. However, expensive electricity in most parts of the country does not make electric furnaces a feasible option for home heating.
Pro Tip: If you decided to go with an all-electric heating, consider installing a heat pump for your central system.
It uses the same ductwork that your furnace would use, but produces heat using a different technology, which consumes much less energy than electric furnace. In addition, heat pumps are reversible and, apart from heating in winter, they can also provide cooling in summer.
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Variable Heating
Another parameter which allows to compare the effectiveness of the furnace is how it varies the output in response to the heating demand. There are three common types:
• Single-stage heating: The furnace switches on when the space temperature goes below the set point on thermostat. Once the desired temperature is reached, the thermostat signals to shut off the burner, while the blower keeps circulating the air for some time to distribute the remaining heat. Single-stage furnaces cycle (switch on and off) more often than other types, since it has to start up every time the temperature drops down below the set point.
The higher the number of starts and stops the furnace performs, the more wear it experiences. In addition, this leads to high fluctuations in space temperatures as the furnace will start only when it is already cold in the room and will usually heat up the space to a higher than desired temperature to keep it above the set point for a longer period.
• Two-stage heating: The furnace is capable of delivering the heat at 100% and around 65% capacities. When the heating boost is required, the furnace automatically switches to a full capacity mode, but during the times of lower heating demand, the furnace will maintain the heat at about 65% capacity. This allows furnace to cycle less, prolonging its lifespan and providing higher levels of comfort.
• Modulating Capacity Heating: The furnace varies the heat output up and down in small increments to keep the exact space temperature set by the user. The operation is typically continuous (long cycles), and the fuel burnt is proportional to the heat output required at any given time. This means that the furnace uses just enough fuel to maintain comfort, resulting in higher efficiencies and elevated comfort. Furnaces of this type usually have AFUE ranging from 96% to 99%.
Did you know? Variable-speed blowers are also available with each type of furnace to optimize efficiency and comfort. The speed of the blower is automatically adjusted to match the air flow with the heating demand.
For instance, the hotter the air produced by the furnace, the lower the air flow is required to heat up the space, avoiding creation of hot spots at the same time.
Pro Tip: Furnace manufacturers sometimes offer two options: a constant and a variable-speed blower. It is especially beneficial to specify a variable-speed blower with single and two-stage furnaces in order to avoid discomfort associated with the cold spots at the start of each cycle. In high-efficiency furnaces, the variable-speed blower typically comes as standard.
Standard-Efficiency Furnace (80%-90%) vs High-Efficiency Furnace (90%-98%)
When the time has come to replace your furnace, the question will naturally arise: which efficiency should you go for to maximize savings?
The answer to this question requires some estimations and will depend on a few factors, such as your current furnace efficiency, the size of your house, how well your house is insulated, how cold the winters are and what the fuel prices are in your area.
The main criterion used for comparison is the payback period of the extra investment, or how fast the new high-efficiency furnace will repay its additional cost. There is a steep rise in the price for the high-efficiency furnace compared to the standard-efficiency one.
For instance, if winters are mild in your location, your furnace will not work as hard as in the cold-winter zones, where more heating will be required, so the energy savings from your furnace will be lower and it will take a long time for a 95% furnace to recoup its higher cost.
Similarly, if your house is very well-insulated and does not lose much heat through the building’s fabric, annual savings from the high-efficiency furnace will be lower.
Pro tip: You can have a rough estimate of how much you will save when switching to a higher efficiency furnace by using online calculators such as this one.
Request a more precise calculation from your HVAC engineer, who will use a specialized software, taking into account all the parameters of your house, to work out the exact saving you might get.
Is a high-efficiency furnace worth the extra money?
Chances are, you are replacing your old, inefficient furnace which has reached the end of its life and are looking to purchase a modern one. Furnaces that are more than 15 years old are usually single-stage and have efficiencies in the range of 56% to 70% AFUE.
For this comparison exercise, we will assume a 65% AFUE furnace is getting replaced by a standard-efficiency 80% or a high-efficiency 95% furnace.
Using an online calculator and considering average gas prices in the US, the results for a 1800 sq. ft. house are the following:
We can see that savings are around 70% larger if you have a high-efficiency furnace in any climate, however, how fast can these savings recoup the higher upfront cost?
Taking $1500 price difference between the standard and high-efficiency furnace and the difference in annual savings, a homeowner in Minneapolis will recover the cost difference in less than 11 years, but a homeowner in Seattle – only after around 21 years.
Considering that the lifespan of high efficiency furnace is anywhere between 15 to 30 years depending on the maintenance frequency, the return of investment of 11 years seems like a good deal.
This means that after 11 years you will start saving “free money” until the end of the furnace life which can be another 10-20 years. In contrast, it will be hard to justify the extra investment for a homeowner in Seattle, where the spent money will only come back closer to the end of the furnace life.
Some other factors will influence the costs and payback periods estimated above. Unlike standard-efficiency furnaces, almost all high-efficiency furnaces are Energy Star certified and will qualify for tax credits and rebates.
You should be able to receive up to $450 in rebates if you purchase a high-efficiency furnace, shortening the payback period by another three years. That’s from 11 years down to 8 years for cold-winter locations!
Nevertheless, additional expenditure might occur when installing a high-efficiency furnace, since they typically use sealed combustion as opposed to atmospheric combustion used in older and most standard-efficiency furnaces.
In the sealed combustion, the air comes from the outside through a PVC pipe and generate acidic exhaust gases that are not suitable for old, unlined chimneys.
This way, you may incur some additional installation costs associated with the new fresh air intake, new chimney or lining of the existing chimney. Sealed combustion ensures higher efficiency, by minimizing heat loses through the combustion chamber walls.
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Low End
$3,300 - $3,900
Mid Range
$4,000 - $4,500
High Efficiency
$4,500 - $5,200
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Did you know? There are ways to improve the efficiency of your heating system without going for a new super-efficiency furnace. For example, you can improve the insulation of your house by sealing drafty doorways, adding insulation to the attic spaces, or even replacing windows with more energy-efficient ones. You can also set up a programmable thermostat which, as per US Department of Energy, will save you an estimated of 10% on heating costs.
Non-financial reasons to consider a high-efficiency furnace
High-efficiency furnaces may not offer financial benefits in some cases, but there are other reasons why homeowners would like to invest in them. One of the reasons is enhanced indoor comfort.
High-efficiency furnaces are generally equipped with a modulating burner that is capable of maintaining the exact internal temperature you want at all times, and it will do so without any disturbing noise. In addition, variable-speed blowers will prevent the cold air blasts that are typical for older single-stage furnaces.
Another reason is the commitment to reduce carbon footprint by burning less fossil fuel and live a more environmentally-friendly lifestyle.
Furnace manufacturer hierarchy
Before we get into the review of the most efficient furnace models, it is worthwhile to have a look at the furnace manufacturer hierarchy.
As you can see from the figure below, there are only a few manufacturers in the market producing furnaces under different brands.
The products from the brands under the same manufacturer are very similar, if not the same. For example, Rheem’s Prestige R98V furnace is identical to the Ruud’s EcoNet Ultra U98V model.
They are sold by different names, but produced by the same manufacturer – Paloma Industries. The same can be said about most Carrier and Bryant furnaces, which are both manufactured by United Technology Corporation (UTS).
In case you cannot find a dealer of your selected furnace in your area, you should be able to locate the same furnace from other brands, but with a different name, as long as they are produced by the same manufacturer.
Top 7 High-efficiency furnaces
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The following is the list of the furnaces with the highest efficiencies for both gas and oil along with their costs and features.
The cost estimates are US averages and can vary widely even from one salesperson to another. That is why always make sure to get at least three quotes from various sellers in order to get the best deal.
Lennox SLP98V High Efficiency Gas Furnace
Cost Range (Installed): $3,250 – $ 5,500
Efficiency (AFUE): up to 98.7%
Warranty: 10-year limited warranty on covered components; limited lifetime heat exchanger warranty
Fuel: Gas
Lennox SLP98V furnace series have the highest efficiency in the industry – up to 98.7%.
It boasts all the features of a super-high efficiency modern furnace: variable-capacity burner capable of controlling the indoor temperature with a precision of 0.5 degrees, variable-speed blower that prevents temperature swings and cold spots at startup, quiet operation and ultra-smart thermostat.
One drawback is that they produce their own proprietary parts, which means that there might be delays in deliveries when replacement of any component is required.
York TM9V High Efficiency Gas Furnace
Cost Range (Installed): $3,000 – $ 6,900
Efficiency (AFUE): up to 96%
Warranty: 10-year limited warranty on parts; limited lifetime heat exchanger warranty; 1-year limited warranty on labor
Fuel: Gas
York TM9V furnace is a high-efficiency, Energy Star certified furnace which has a two-stage burner and a variable-speed blower. The temperature control might not be as precise as in furnaces with modulating burners, but it is a very compact unit that can fit into tight spaces.
It also has an integrated self-diagnostic control module. Apart from a lifetime heat-exchanger warranty and 10-year parts warranty, common among all super high-efficiency models, it also provides a 1-year warranty on labor.
Carrier Infinity 98 59MN7 High Efficiency Gas Furnace
Cost Range (Installed): $3,000 – $ 5,300
Efficiency (AFUE): up to 98.5%
Warranty: 10-year limited warranty on parts; limited lifetime heat exchanger warranty
Fuel: Gas
Carrier Infinity 98 59MN7 furnace offers all the usual perks of a high-efficiency furnace including modulating burner and variable-speed blower.
In fact, Carrier was an early adopter of variable capacity heating, so you can expect a reliable operation for improved comfort. An additional feature is the ability to combine the furnace with a heat pump under one system which results in a dual fuel heating: gas and electricity.
When the outdoor temperatures are above freezing, heat pump does the job at a lower cost. Once the temperatures drop below freezing, the gas furnace takes over and provides reliable high-efficiency heating.
If you cannot find this model in your area, try to look for Bryant Evolution 987M. It is a very similar furnace made by the same manufacturer.
Goodman GMVM97 High Efficiency Gas Furnace
Cost Range (Installed): $2,500 – $4,000
Efficiency (AFUE): up to 98%
Warranty: 10-year limited warranty on parts; limited lifetime heat exchanger warranty; 10-year unit replacement limited warranty
Fuel: Gas
Goodman GMVM97 is a great alternative to expensive brands like Carrier, Lennox or York. Most parameters are the same, including 98% efficiency, modulating burner, variable-speed blower, and even warranties (lifetime heat exchanger and 10-year parts warranties), but the cost is slightly less.
Goodman also offers its new ComfortBridge smart control technology, which shifts the indoor climate control from a thermostat into the HVAC equipment itself. It is particularly useful if you have other Goodman HVAC equipment installed such as their central air-conditioner or heat pump.
Note that the same furnace is available as Amana AMVM97 and Daikin DM97MC in case Goodman model is not available in your area.
Rheem Prestige R98V High Efficiency Gas Furnace
Cost Range (Installed): $2,750-$4,200
Efficiency (AFUE): up to 98%
Warranty: 10-year limited warranty on parts; limited lifetime heat exchanger warranty; limited lifetime conditional unit replacement warranty
Fuel: Gas
Rheem Prestige R98V furnace offers one of the highest efficiencies in the market at a lower cost than most well-known brands, while also having a modulating burner, variable-speed blower and same warranty periods. It was crowned as one of the most efficient furnaces by Energy Star in 2017.
A special feature of this furnace is WiFi enabled EcoNet control center, which serves as a hub for communication for a home’s heating system operated from the user-friendly display, web portal or a mobile app.
Paloma Industries, which manufacture Rheem furnaces, also produce the same furnace under the Ruud EcoNet Ultra U98V model name.
Adams AHEO Highboy Condensing Oil Furnace
Cost Range (Installed): $7,500-$10,500
Efficiency (AFUE): up to 95%
Warranty: 5-year warranty on parts; 20-year warranty on heat exchanger
Fuel: Oil
If gas furnace is not an option for you due to the lack of gas network infrastructure in your area, oil furnace can be considered. Adams AHEO Highboy is the highest-efficiency oil furnace which uses a condensing technology similar to high-efficiency gas furnaces. Adams is claimed to be the most reliable manufacturer of oil-fired furnaces; however, the quality comes at a high price, even higher than most high-efficiency gas furnaces from popular brands.
Although it can compete with gas-fired furnaces in high efficiency, it still has a single-stage burner and the warranty is much less attractive: 20 years on the heat exchanger and 5 years on parts.
Thermo Pride OL6 Oil Furnace
Cost Range (Installed): $2,400 – $4,370
Efficiency (AFUE): up to 87%
Warranty: 10-year limited warranty on parts; limited lifetime heat exchanger warranty
Fuel: Oil
Another oil-fired furnace to consider is Thermo Pride OL6.
The efficiencies are only up to 87%, but it is still considered as high efficiency among oil-fired furnaces, with most of the models certified by Energy Star.
It also offers a compact design that is perfect for installations with height constraints. The burner is single-stage, but there is an option to install a variable-speed blower for greater thermal comfort and less noise.
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Low End
$3,300 - $3,900
Mid Range
$4,000 - $4,500
High Efficiency
$4,500 - $5,200
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Which energy efficient furnace is right for you?
Which type of furnace to go for to be in a winning position is not a straight forward question to answer on the spot. However, with some calculations, it is possible to determine exactly what efficiency – standard or high – is the most beneficial in your situation.
However, it can be said with certainty that a high-efficiency furnace is hard to justify in climates with mild winters.
On the other hand, if your intention is to achieve higher comfort levels in your house or perhaps reduce your carbon footprint no matter the cost, the super high-efficiency furnace is a perfect option for you.
For an easier comparison between the top high-efficiency gas and oil-fired furnaces, refer to the table below:
Top 7 Most Efficient Gas and Oil-Fired Furnace Comparison
The most attractive option on the list above is Goodman GMVM97 gas furnace. It has all the features and characteristics of the modern high-efficiency furnace, but for a lower price than more popular competitors such as Carrier or York.
Goodman has overcome the reputation of a budget brand and offer high-quality furnaces at more affordable prices.
Among the oil-fired furnaces, Thermo Pride OL6 offers a good relationship between the price and efficiency. Considering that oil-fired furnaces typically do not have efficiencies higher than 90%, this Energy Star certified model is a good option if oil is the only fuel available for heating your house.
