Furnace Sizing Calculator

Typical Cost To Install New Furnace Average: $4,160 - $5,730
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Furnace Size Calculator accurately estimates furnaces equipment size in BTUs as well as installation cost of a gas furnace – standard & high efficiency with AFUE ranges of 80-98%.

Calculate Gas Furnace Cost & Size in Virginia

sq. ft.
Low End
$0
Mid Range
$0
High End
$0
Estimated Load Heating: 0 BTU
Recommended Equipment Heating:

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Climate Region / Zone: Your estimated location is Virginia - Climate Region #3

Your location on the climate zone determines the heat load needed for your furnace.

Some states have multiple climate zones/regions. Please adjust your climate region as needed - see map below:

NOTE: These furnace cost estimates take in to account the most recent price increases for materials, that went into effect from Nov 2022, and will remain relatively unchanged through 2023, unless there is a significant spike in inflation.

How To Use Furnace Sizing Calculator

This Furnace Size Calculator is pretty straight-forward to use, and accounts for the the type of fuel & efficiency of your furnaces.

For example, if your fuel is OIL, the efficiency will automatically change to 85% AFUE, which is the only type of furnace available for OIL.

It also automatically calculates heat loss in the exhaust (either chimney or direct vent through PVC piping), and adds this loss to the BTU requirements (unit size).

STEP 1: Using a “Region Map” select your heating zone – this will determine the heating BTUs per square foot.

STEP 2: Enter your home’s square footage (heated area only).

STEP 3: Select desired furnace efficiency. Note that a 95% AFUE (high efficiency) is pre-selected as it’s a most installed type of Gas Furnace today. All high efficiency furnaces are “direct-vented”, and cannot be vented into a chimney. If that is an issue, select an 80% AFUE.

STEP 4: Select your heating fuel type – Natural Gas or Heating Oil. We are working on adding option for Propane furnaces.

However, for the most part, propane equipment is very similar in cost to install.

The main difference between Gas, Oil and Propane would be fuel (energy) price. Use our Heating Fuel Costs Calculator to estimate your annual energy cost, and usage, based on your location, home size and equipment type (Furnace / Boiler / Geothermal or Air Source Heat Pump and Resistance Electric Heating).

To give you an idea of how much different heating fuels cost per season, here are the numbers in Massachusetts, for a 1900 sq. ft. home (the default size in our calculator), with a 95% AFUE furnace.

Fuel Type Units Cost/Yr.
Natural Gas: 1,164 Therms $2,055
Heating Oil: 839 Gal $2,797
Propane: 1,272 Gal $4,530

STEP 5: Select your project type. For most folks, this would be a retrofit job (Replacing old system). If you have a new construction project or a completely gutted house, often you will need ducts installed. See next section OR use our Duct Cost Calculator.

STEP 6: Select if you need ducts installed. Prices are calculated for new INSULATED ducts, with 8R insulation.

STEP 7: Optional setting:

– Ceiling Height
– Insulation Grade
– Windows/Doors Air Tightness
– Windows quantity
– Exposure to the Sun

Optional items above may affect your heat loss / heat gain, thus increasing or decreasing BTU load needed to heat your home.

STEP 7: Calculate the BTU load, size of furnace(s) recommended for your home, and average installation prices. You will get Low End, Mid Range and High End pricing.

Most homeowners go with the mid range price quote.

However, if you hire an experienced installer who just opened their business, you can often get better pricing, and a good quality installation.

Average Costs For:
Most Homeowners Spent Between: Most People Spent: $4,160 - $5,730
Low End
$3,970
Average
$4,420
High End
$6,490

See costs in your area Start Here - Enter Your Zip Code


How Much Does It Cost to Install A Gas Furnace?

Installing a typical 95-96% AFUE (efficiency) furnace costs $4,415 to $5,448 including all labor and materials.

Your furnace replacement cost will depend on home size, and does not include upgrading (increasing & insulating) the ductwork.

This price estimate is for a 100K BTU, 95% AFUE Furnace, which is appropriate for a 2000 sq. ft. home, with average insulation.

The question is – how are these prices estimated? Let’s take a look.

– For the equipment, the furnace itself, exhaust, drainage and other accessories, it costs between $1,950 and $2,200 , including sales tax.

– For labor, a typical HVAC contractor charges $70 per hour (including taxes, insurance, benefits, etc). It takes about 24 man-hours of labor to get your furnace up and running. So we get $1,680 for labor.

– The third ticket item would be contractor’s overhead and profit. Remember, that if contractor does not make profit – who’s going to repair your heating system if there is a warranty issue? Also contractors have operating costs. So we figure about 25-30% goes to expenses and profits.

From there we get a $5,000 average cost to install a new Gas Furnace. This includes all the material price increases that happened in 2021, and were caused by the supply shortages due to Covid-19, etc.

Installing a heat pump together with a furnace costs $6,100 – 10,000+, including all equipment and professional installation.

Pro Tip: many states offer an energy savings tax credits & rebates from your local utility company and/or state energy conservation agency.

Furnace prices include professional labor and materials needed to replace or install a warm air furnace, and (optional) new ductwork.

In many states, homeowners can receive “energy efficiency” tax credits and cash rebates for installing a furnace with an AFUE rating of 95% or higher.

These rebates can cover up-to 25% of your out of pocket furnace installation costs.

For example in Massachusetts, there is a $1,000 rebate for 95% AFUE furnace with ECM motor, and $1,250 for 97% AFUE furnace with ECM.

Typical Cost To Install New Furnace Average: $4,160 - $5,730
See costs in your area

Furnace Efficiency

Installing a new high efficiency furnace will significantly improve the heating comfort in your home, and provide noticeable energy cost savings.

Now it is especially important to reduce your heating bill, when Gas, Electricity and Oil prices are on the rise, and you can do so by upgrading your old 76% efficiency furnace to a 92-97% high-efficiency unit.

Whether or not you should opt for high efficiency furnace (versus a standard 80% efficiency unit), is a topic for a separate discussion, which we will cover soon on our blog.

PRO TIP: While high efficiency furnaces will reduce your heating energy usage by up-to 18%, majority of heat loss in your house happens through uninsulated ducts, roof/attic, leaky/drafty windows & doors, etc. Therefore, we also recommend improving your home insulation, and not just relying on installing a 98% AFUE furnace.

If you have old, uninsulated ducts, you will be losing as much as 25-30% of your heat in those ducts alone. Same goes for walls/attic/windows.

Consider insulating your attic, which can reduce heat loss by 10-15%.

New triple glaze windows can reduce total house heat losses by 5-7%, and installing spray foam or blown-in insulation into hollow wall cavities can reduce house heat loss by another 7-10%.

Last but not least – the biggest offender causing warm air heating energy losses is uninsulated ducts.

Consider insulating or replacing your ducts.

If your monthly heating bill is $500, at least $100 of that is lost in your ducts. Next time you do duct cleaning, you may find some “benjamins” in there 🙂

One more thing to consider about your existing ductwork is the air flow requirement for high efficiency furnaces (with ECM motors).

ECM motors move air at much higher velocity and volume, compared to standard blower motors, and therefore need bigger ducts, for both supply and return air. Duct size is insufficient, the efficiency of an ECM motor furnace drops.

Average Costs For:
Most Homeowners Spent Between: Most People Spent: $4,160 - $5,730
Low End
$3,970
Average
$4,420
High End
$6,490

See costs in your area Start Here - Enter Your Zip Code


What Size Furnace Do I Need?

Multiple Furnaces and Equipment recommendations: For bigger projects (homes over 3000 sq. ft.), the largest BTU size furnace (125K BTUs) may not be sufficient.

In such cases, multiple furnaces will be utilized. Our calculator will spec multi unit jobs at multiples of 125K BTUs, and the remainder in steps of 40K, 60K, 80K, 100K, 110K and 120K BTU sizes.

For example – your job needs 160K BTUs of heating. We will price a 125K + 40K BTU system.

While you could instead go with 80K + 80K, that would overly complicate this already complex algorithm, while the price will remain the same or similar.

Since our equipment recommendation is for reference and information purposes only, the actual equipment decision should be made between you and your Furnace Installer.

Heat loss in the ducts and through the chimney

We add 8.5% heat loss coefficient to account for your duct losses. If you have insulated metal ducts, this figure could be as high as 15% or more.

Our calculator also accounts for exhaust gas heat lost through the chimney or into direct vent. This is where the High Efficiency furnace shows much better performance compared to a regular efficiency 80% unit. Your “chimney” loss is only 3-5% compared to 20% for an 80% furnace.

This loss ratio is calculated in the BTU load, and recommended equipment is selected based on target heat load.

You can use advanced options to simulated improving your house insulation and windows, which will result in lower heat loss, and thus, lower BTU load requirement.

Typical Cost To Install New Furnace Average: $4,160 - $5,730
See costs in your area


About Leo B

Leo has been a contractor since 2003, specializing in: roofing, siding, general contracting (GC) and residential remodeling. Leo is also a Certified HVAC, Oil & Gas Heating Technician/Installer. In addition to roofing and remodeling, Leo is passionate about Solar, green building and energy conservation, so a lot of my time and energy goes to installing energy efficient heating and cooling systems.


See more about Remodeling Calculator team here


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One comment on “Furnace Sizing Calculator

  1. Tom Roach

    My elderly mom just got a quote for 4000 to install a Goodman 60000 btu furnace in a house that is 1550 square feet. It seems to small of btu. What is your professional opinion

    Reply