How Much Electricity a Gas Furnace Uses Per Month

The amount of electricity a gas furnace uses per month varies by model, blower motor type, thermostat settings, climate, and run-time. This article explains how to estimate monthly kWh usage, compares typical ranges, and offers tips to reduce electricity consumption and costs.

Furnace Type	Typical Blower Power (Watts)	Estimated Monthly kWh (Heating Season)
Standard PSC Motor	300–900 W	50–300 kWh
High-Efficiency ECM Motor	50–300 W	10–100 kWh
Modulating Furnace With ECM	30–200 W	8–60 kWh

How Gas Furnaces Use Electricity

A gas furnace primarily burns natural gas or propane to generate heat, but it still uses electricity for components such as the blower motor, ignition system, control board, and fans. The blower motor is the dominant electrical load, running whenever the furnace circulates heated air.

Main Electrical Components And Their Typical Power Use

Blower Motor

Blower motors come in two main types: permanent split capacitor (PSC) and electronically commutated motors (ECM). PSC motors are older and less efficient, typically drawing 300–900 watts when running. ECMs are variable-speed and much more efficient, commonly using 50–300 watts.

Ignition And Control Systems

Modern furnaces use electronic ignition and control boards that draw minimal power, usually under 20 watts when active. The intermittent spark or hot surface igniter consumes power only briefly during each start cycle.

Inducer Fan And Draft Components

High-efficiency furnaces use an inducer fan to vent combustion gases, typically drawing 50–200 watts during operation. This fan runs only during heating cycles, adding to total electrical usage.

Estimating Monthly Electricity Use For A Gas Furnace

To estimate monthly electricity use, calculate the blower motor watts multiplied by average run hours per day, then multiply by days in the month and divide by 1,000 to convert to kWh. Add other component loads if needed.

Example Formula: Monthly kWh = (Motor Watts × Hours Per Day × Days Per Month) ÷ 1000

Example Calculations

Example 1: A house with a PSC blower using 700 W that runs 6 hours per day for 30 days: (700 × 6 × 30) ÷ 1000 = 126 kWh/month.

Example 2: A house with an ECM blower using 150 W that runs 8 hours per day for 30 days: (150 × 8 × 30) ÷ 1000 = 36 kWh/month.

Typical Monthly kWh Ranges Based On Climate And Efficiency

Monthly electrical usage of gas furnaces varies widely by climate and system efficiency. In mild climates, run-times are shorter; in cold climates, furnaces run longer and often use more electricity.

• Mild Climates: 10–50 kWh/month with ECMs, 30–120 kWh/month with PSC motors.
• Moderate Climates: 30–100 kWh/month with ECMs, 80–250 kWh/month with PSC motors.
• Cold Climates: 60–200 kWh/month with ECMs, 150–400+ kWh/month with PSC motors.

Factors That Affect Monthly Electricity Consumption

1. Motor Type

ECM motors significantly reduce electricity use compared to PSC motors because they modulate speed and maintain airflow efficiently.

2. Furnace Age And Efficiency

Older furnaces often have less efficient blowers and controls that increase electrical draw. High-efficiency furnaces (AFUE 90%+) may include additional electrical components like condensate pumps, adding small amounts of usage.

3. Thermostat Settings And Cycling

Higher thermostat settings or frequent cycling increase blower runtime. Smart thermostats can optimize cycles and reduce electrical run-time while maintaining comfort.

4. Home Insulation And Air Leakage

Poor insulation or air leaks force the furnace to run longer to maintain temperature, increasing both gas and electrical usage. Sealing and insulating reduce runtime and electricity consumption.

5. Duct Design And Airflow Resistance

Restricted ducts or oversized systems can cause longer blower runtimes and higher watt draw. Properly designed ducts and regular maintenance lower electrical use.

How To Measure Actual Electricity Use

Smart Meter And Utility Bills

Monthly electricity use can be observed from electric utility bills. Look for changes during heating months and compare to non-heating months to estimate furnace-related usage.

Plug-In Power Meters

For furnaces with accessible external components (like dedicated blower plugs), a plug-in power meter measures watts and cumulative kWh. Many furnaces are hardwired, making this option less feasible without a professional.

Clamp Meter Or Energy Monitor

An electrician can use a clamp meter on the furnace circuit to measure amperage and calculate watts. Whole-home energy monitors installed at the electrical panel provide detailed real-time and historical data and can isolate HVAC consumption patterns.

Cost Implications And Examples

Electricity cost depends on local rates. At $0.15 per kWh, a furnace drawing 100 kWh/month costs $15. If electricity costs $0.30 per kWh, the same usage costs $30.

Monthly kWh	Cost @ $0.12/kWh	Cost @ $0.18/kWh	Cost @ $0.30/kWh
25 kWh	$3.00	$4.50	$7.50
100 kWh	$12.00	$18.00	$30.00
250 kWh	$30.00	$45.00	$75.00

Ways To Reduce Furnace Electricity Use

Upgrade To An ECM Motor

Replacing a PSC blower with an ECM can cut blower energy use by 40–70%. This retrofit is often cost-effective over the life of the furnace, especially in cold climates.

Use A Smart Thermostat

A smart thermostat reduces unnecessary runtime by optimizing schedules, adapting to occupant patterns, and using geofencing or learning algorithms to avoid wasteful heating.

Improve Home Envelope

Adding insulation, weather-stripping doors and windows, and sealing ducts reduces heat loss and lowers furnace run-time, cutting both gas and electricity usage.

Maintain The System

Regular air filter changes, annual professional tune-ups, and ensuring proper airflow keep the furnace running efficiently, which minimizes electrical draw and prevents excessive cycling.

Use Zoning Or Ceiling Fans

Zoning systems allow heating only occupied areas, reducing overall furnace runtime. Ceiling fans in reverse winter mode can redistribute warm air and reduce thermostat demand.

When Electricity Use Is Unusually High

If electricity use from the furnace appears higher than expected, investigate these common causes: blocked return vents, failing ECM or blower motor, short-cycling due to thermostat or limit switch issues, or an incorrectly sized system.

Professional diagnostics are recommended when simple checks (filter, vents) do not explain high usage. An HVAC technician can test motor amperage, inspect controls, and recommend repairs or replacement.

Comparing Electric Furnace Vs Gas Furnace Electricity Use

Electric resistance furnaces consume much more electricity because they use electric heating elements rather than gas. A gas furnace’s electrical use is modest and typically limited to blower motor and controls, making it far less electricity-intensive than an all-electric system.

Key Takeaways For Homeowners

• Blower motor type is the major determinant of a gas furnace’s monthly electricity use: ECMs are far more efficient than PSC motors.
• Typical monthly consumption ranges from about 10–400 kWh depending on climate, motor type, and runtime.
• Upgrades such as ECM retrofits, smart thermostats, and improved insulation offer the best opportunities for reducing electrical use and costs.
• Measure actual usage with whole-home monitors or professional metering to get accurate data for decision-making.

Resources And Further Reading

For detailed specifications, consult furnace manufacturer manuals and the U.S. Department of Energy website for guidance on HVAC efficiency and motor standards. Local utility websites often offer energy-saving programs and rebates for ECM upgrades and smart thermostats.

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