Propane vs. heat pump, worked all the way through

The three constants that do not change

Two of the numbers in this comparison are physics and one is a nameplate rating. None of them are marketing.

Propane energy content

91,502 BTU per gallon (higher heating value). Fixed. Does not vary by supplier.

Electrical equivalent

3,412.14 BTU per kilowatt-hour. Also fixed.

HSPF2

Delivered BTU per watt-hour, seasonally averaged, measured under the current federal test procedure. A rating, not a promise, but it is the only comparable figure published.

Everything else — your gallons, your price per gallon, your furnace's actual AFUE, your EMC rate — is specific to your house and is what the calculator asks you for.

Why AFUE is the input people underestimate

Homeowners routinely quote their furnace as more efficient than it is. A unit installed before roughly 1992 is frequently 65–75% AFUE in practice. A 1990s-2000s mid-efficiency unit is typically 78–82%. Only condensing furnaces with a PVC flue reach 90%+.

If your flue is metal and vents through a masonry chimney or a metal B-vent, you are almost certainly on the lower end. That single input moves the comparison more than the price of propane does, because it determines how many of your gallons never became heat.

The part that decides it: fuel price behavior

A single-year snapshot understates the case, because propane and electricity do not behave the same way as prices.

Propane is a commodity delivered by truck to a rural address. Its price carries crude and natural-gas linkage, winter demand spikes, regional supply constraints and a delivery-logistics component that is worse the further you are up a mountain. It is volatile, and the volatility is asymmetric — it spikes in the season you need it.

Electricity from an EMC is a regulated cooperative rate. It moves, but it moves in small, announced, board-approved steps. Over a ten-year hold the difference in variance is arguably worth more than the difference in mean price, particularly for a fixed-income household.

Where the break-even usually lands

For a Pickens County house burning 700–1,000 gallons a winter through an 80% furnace, replacing at end of life, the equipment premium over a like-for-like propane furnace replacement is typically recovered in three to six heating seasons on operating cost alone.

Two things move that materially. A required electrical service upgrade pushes it out. Any active rebate or subsidised financing pulls it in sharply — which is why the financing page and the rebate status page matter more than the equipment brochure does.

If your furnace is not at end of life, the honest answer is that the payback stretches, because you are then paying for a working appliance's replacement rather than choosing between two replacements.

Common questions about propane vs heat pump: the BTU math

Where these numbers come from

• U.S. Energy Information Administration — energy conversion calculators — heat content of a gallon of propane
• EIA weekly heating oil and propane prices — the $/gallon series behind the worked examples
• AHRI Directory of Certified Product Performance — verify any quoted HSPF2, SEER2 and capacity rating

Every contractor in this network holds a current Georgia Conditioned Air or Electrical Contractor license. You can confirm any license yourself before you sign anything — Georgia Secretary of State license lookup.