Older homes have character, charm, and often a few quirks when it comes to comfort. Drafty windows, aging insulation, and outdated wiring or chimneys can make heating less efficient and more expensive. That’s why the type of furnace you choose—gas or electric—plays an even bigger role in older houses than in newer construction.
In this article, I’ll break down how gas and electric furnaces perform in older homes, what challenges to expect, and which option might be best depending on your situation.
👉 For the bigger picture, see our main guide: Gas vs. Electric Furnaces: Which is Better?
Why Furnace Performance Matters More in Older Homes
Unlike tightly sealed modern houses, older homes often face issues that can magnify furnace inefficiency:
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Insulation gaps – Many pre-1980s homes lack wall insulation or have settled attic insulation.
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Leaky ductwork – Duct systems may not be sealed, wasting 20–30% of conditioned air according to the U.S. Department of Energy.
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Outdated infrastructure – Aging chimneys, electrical panels, and wiring can complicate installation.
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Uneven heating – Drafts and poor airflow make it harder to keep every room comfortable.
In short, the same furnace may perform very differently in an older home compared to a newer one.
Gas Furnace Performance in Older Homes
Heating Power and Speed
Gas furnaces deliver high heat output (BTUs) quickly, making them well-suited for drafty homes in cold climates. Older houses often lose heat rapidly, so this “fast recovery” is a major advantage. According to Trane, modern gas furnaces can reach efficiency ratings of 95% or higher, which means nearly all the fuel is converted into usable heat instead of being lost through exhaust.
Venting and Safety Requirements
One challenge: older homes may need updates to safely vent combustion gases. If you have a masonry chimney, it might require relining before connecting a modern gas furnace. Without proper venting, carbon monoxide risks increase. That’s why EPA recommends installing CO detectors on every level of your home when using combustion appliances.
Utility and Maintenance Considerations
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Fuel costs: Natural gas tends to be cheaper per BTU than electricity in most U.S. regions.
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Maintenance: Gas furnaces need annual inspections to check burners, heat exchangers, and venting.
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Lifespan: A well-maintained gas furnace can last 15–20 years.
For older homes in colder climates, gas usually provides stronger, faster heating at lower operating costs—provided venting and gas line access are available.
Electric Furnace Performance in Older Homes
Installation and Electrical Capacity
Older homes often lack the electrical infrastructure for high-capacity furnaces. Many electric furnaces require 60–120 amps of dedicated service. If your home still runs on a 100-amp panel or has outdated wiring, you may need an electrical upgrade. The International Code Council enforces safety standards for panel capacity, wiring, and grounding that must be met before installation.
Heating Comfort and Consistency
Electric furnaces provide even, steady heating but tend to warm up slower than gas models. In drafty or poorly insulated homes, this can feel less comfortable during cold snaps. However, in milder regions or smaller older homes, electric can still perform adequately.
Operating Costs and Efficiency
On a per-BTU basis, electricity is typically more expensive than gas. The ASHRAE notes that efficiency is less about furnace type and more about whole-home performance—insulation, duct sealing, and windows. That said, electric furnaces have nearly 100% efficiency at the unit level since no energy is lost through combustion. Pairing them with solar or renewable energy can help offset higher costs.
Comparing Gas vs. Electric in Real-World Older Homes
Scenario 1: Cold, Drafty House with a Chimney
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Best fit: Gas furnace
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Why: High BTU output and quick recovery keep up with heat loss. But chimney relining may be required.
Scenario 2: All-Electric Home Built in the 1960s
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Best fit: Electric furnace or heat pump
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Why: No existing gas line, and adding one would be costly. Panel upgrade may be required but cheaper than trenching a new gas line.
Scenario 3: Renovated Historic Home with Upgraded Insulation
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Best fit: Either option, depending on local energy rates
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Why: With weatherization improvements, operating costs narrow, making both systems viable.
Key Factors to Consider Before Choosing
Before committing to gas or electric in an older home, evaluate:
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Infrastructure: Do you already have a safe chimney or gas line? Or is your electrical panel up to code?
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Upgrade costs: Relining a chimney can cost $1,500–$3,500. Electrical panel upgrades average $1,500–$3,000.
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Climate: Gas tends to outperform in cold regions; electric may suffice in milder ones.
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Safety: Combustion appliances require CO detectors; electric reduces that risk but can stress old wiring if not updated.
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Resale value: In colder markets, buyers often favor gas for efficiency. In all-electric or eco-conscious markets, electric may be more attractive.
Final Takeaway for Homeowners
For older homes, gas furnaces often outperform electric when it comes to raw heating power and lower operating costs. But electric furnaces may be a better fit in homes without safe venting or where major electrical upgrades are already planned.
The truth is, your home’s infrastructure and local energy rates often dictate the smarter choice more than the furnace itself. Before deciding, get an HVAC professional to perform a load calculation and an inspection of your wiring, ductwork, and insulation. That way, you’ll know not only which system will perform best—but also what upgrades may be required to make it safe and efficient.
👉 Next up in this series: Do Gas or Electric Furnaces Work Better with Heat Pumps?
Alex Lane
Your Home Comfort Advocate
