A gas furnace primarily burns natural gas or propane to produce heat, but it still uses electricity for components such as the blower motor, ignition system, controls, and safety devices. Estimating daily electricity use requires understanding component power ratings, runtime, and climate-driven duty cycles. This article explains typical electrical loads, shows calculation examples, and offers practical ways to measure and reduce electricity consumption.
| Component | Typical Power Draw | Daily kWh Range (Example) |
|---|---|---|
| Blower Motor (Variable-Speed) | 200–800 W | 1.5–9.6 kWh |
| Single-Speed Blower | 400–1200 W | 3.2–14.4 kWh |
| Inducer/Exhaust Fan | 75–200 W | 0.6–1.6 kWh |
| Electronic Ignition/Control | 10–50 W | 0.08–0.4 kWh |
| Total Typical Daily Use | — | 2–16 kWh (most homes) |
Content Navigation
- How Gas Furnaces Use Electricity
- Typical Power Draws For Furnace Components
- Calculating Daily Electricity Use: Step-By-Step
- Factors That Drive Daily Electricity Use
- Estimating Cost: How Much Does That Electricity Cost?
- How To Measure Actual Electricity Use
- Practical Tips To Reduce Furnace-Related Electricity Use
- When Electricity Use Is Unusually High
- Energy Efficiency And Interactions With Gas Consumption
- Regulatory And Incentive Considerations
- Frequently Asked Questions
- Key Takeaways
How Gas Furnaces Use Electricity
Although combustion provides heat, a gas furnace relies on several electrically powered parts. The most significant is the blower motor that circulates warm air through ducts. Other electrical consumers include the inducer/exhaust fan, electronic ignition and control board, thermostat (especially smart thermostats), and safety devices like pressure switches.
Typical Power Draws For Furnace Components
Understanding component wattages is essential to calculate daily use. Typical ranges are based on common residential furnaces in the U.S.
Blower Motor
Blower motors vary widely: single-speed PSC motors often draw 400–1200 watts while variable-speed ECM motors commonly draw 200–800 watts depending on airflow and speed. The blower operates both during heating calls and often continuously if the fan is set to ON.
Inducer/Exhaust Fan
The inducer motor runs during ignition and while the burner is operating to maintain safe venting. Typical power is 75–200 watts and runtimes are proportional to burner cycle lengths.
Ignition, Controls, And Thermostat
Electronic ignition systems, control boards, and pressure switches draw modest power, typically 10–50 watts combined during operation. Smart thermostats may draw an additional few watts continuously.
Heat Strip Or Electric Supplement (If Present)
Some gas furnaces include electric heat strips for backup or supplemental heat. These can draw 1,000–5,000+ watts and dramatically increase electrical consumption when engaged.
Calculating Daily Electricity Use: Step-By-Step
Calculations require component power, average runtime per day, and the formula: kWh = (Wattage × Hours)/1000. Two realistic examples show typical daily use for moderate and cold climates.
Example 1: Mild Climate, Efficient Furnace
Assumptions: ECM blower at 300 W running 6 hours/day, inducer 100 W running 2 hours, controls 20 W continuous for 24 hours but mostly idle draws estimated 5 W effective while not running.
Blower: (300 W × 6 h)/1000 = 1.8 kWh. Inducer: (100 W × 2 h)/1000 = 0.2 kWh. Controls/Thermostat: (5 W × 24 h)/1000 = 0.12 kWh. Total ≈ 2.12 kWh/day.
Example 2: Cold Climate, Single-Speed Blower
Assumptions: Single-speed blower at 800 W running 12 hours/day, inducer 150 W running 8 hours, controls 10 W effective continuous.
Blower: (800 W × 12 h)/1000 = 9.6 kWh. Inducer: (150 W × 8 h)/1000 = 1.2 kWh. Controls: (10 W × 24 h)/1000 = 0.24 kWh. Total ≈ 11.04 kWh/day.
Factors That Drive Daily Electricity Use
Several variables make daily electrical consumption vary widely between homes.
- Climate And Heating Demand: Colder climates increase burner cycles and blower runtime, raising electrical use.
- Furnace Type And Efficiency: High-efficiency condensing furnaces may use slightly more electricity for controls and condensate pumps but reduce gas consumption overall.
- Blower Motor Type: ECM variable-speed motors are typically more efficient and can use less electricity compared to older PSC single-speed motors when properly configured.
- Fan Setting: Leaving the fan on continuously can add several kWh per day depending on motor power.
- Supplemental Electric Heat: Heat strips or electric auxiliary heat are major electrical loads when engaged.
- Home Size And Insulation: Larger, poorly insulated homes need longer runtimes to maintain temperature.
Estimating Cost: How Much Does That Electricity Cost?
To convert kWh to dollars, multiply kWh by the local electricity rate. The U.S. national average retail rate is roughly $0.16 per kWh but varies by state.
Using the two examples: Mild climate at 2.12 kWh/day × $0.16 = $0.34/day. Cold-climate example at 11.04 kWh/day × $0.16 = $1.77/day. Homes using auxiliary electric heat can see much higher daily costs.
How To Measure Actual Electricity Use
Estimations can be refined by direct measurement with a clamp meter, plug-in energy meter, or whole-home energy monitor.
- Clamp Meter: Measures current on furnace circuits; multiply amps × volts × hours to get kWh.
- Plug-In Meter: Useful for external components like furnaces with plug-in blowers or standalone heat strips.
- Whole-Home Energy Monitor: Provides detailed usage by circuit or whole-home load patterns and helps isolate HVAC contributions.
Practical Tips To Reduce Furnace-Related Electricity Use
Reducing electricity without sacrificing comfort often focuses on blower operation, controls, and system tuning.
- Use Programmable Or Smart Thermostats: Optimize setpoints and reduce blower runtime during unoccupied hours.
- Avoid Continuous Fan Setting: Set fan to AUTO rather than ON to limit blower hours unless continuous circulation is necessary for air quality.
- Upgrade To An ECM Blower: When replacing the furnace or blower, choose an ECM motor for higher efficiency and variable airflow control.
- Seal And Insulate Ducts: Reducing duct leakage improves delivery efficiency, which can reduce blower run time.
- Schedule Professional Maintenance: Proper tuning, filter changes, and combustion checks keep blower and inducer motors operating efficiently.
- Minimize Use Of Electric Heat Strips: Use setpoints to avoid triggering auxiliary electric heat; ensure the gas furnace and thermostat are configured correctly.
When Electricity Use Is Unusually High
If measured electrical use from the furnace circuit appears high, consider potential causes.
- Faulty Blower Motor: A failing motor can draw excess current or run inefficiently.
- Incorrect Fan Settings Or Wiring: Fan on modes, improper fan relays, or wiring issues can keep the blower running at high speeds.
- Stuck Relay Or Control Board Faults: These can cause continuous operation of motors or auxiliary components.
- Frequent Short Cycling: Rapid burner on/off cycles increase inducer and ignition runs, raising electricity use.
Have an HVAC technician inspect systems showing abnormal electrical loads to diagnose mechanical or control faults.
Energy Efficiency And Interactions With Gas Consumption
Using electricity efficiently does not necessarily mean lower gas consumption; both should be optimized. High-efficiency furnaces (AFUE of 90%+) waste less gas and may use slightly more electrical power for controls and condensate pumps, but overall energy cost often decreases.
Combining a high-efficiency gas furnace with good insulation, programmable thermostats, and efficient blowers yields the best overall energy outcome.
Regulatory And Incentive Considerations
Federal, state, and utility incentives sometimes support upgrades to high-efficiency furnaces, ECM motors, and smart thermostats. Rebates and tax credits can offset upgrade costs and reduce lifecycle energy expenditure.
Check local utility programs and state energy office resources for available incentives tailored to HVAC upgrades.
Frequently Asked Questions
Does A High-Efficiency Furnace Use More Electricity?
High-efficiency condensing furnaces may use slightly more electricity for controls and condensate pumps, but they reduce gas consumption significantly, lowering overall energy cost in most cases.
How Much Electricity Does A Furnace Fan Use If Always On?
An always-on fan can add several kWh per day depending on motor type. For example, a 400 W blower running 24 hours uses 9.6 kWh/day, which can be a major portion of the furnace electrical draw.
Will A Smart Thermostat Increase Electricity Use?
Smart thermostats draw a few watts continuously but typically reduce overall HVAC runtime by optimizing schedules and setback strategies, leading to net energy savings.
Key Takeaways
Most gas furnaces use between about 2 and 12 kWh per day in typical U.S. homes, depending on climate, blower motor type, and runtime. Auxiliary electric heat and continuous fan operation are the biggest drivers of higher electricity use. Accurate measurement with a meter and targeted upgrades—ECM blowers, smart thermostats, and duct sealing—can reduce electrical consumption and costs.
For precise evaluation, measure current draw and runtime or consult a qualified HVAC professional for diagnostics, tuning, and upgrade recommendations tailored to the specific home and climate.
Tips for Getting the Best HVAC Prices
- Prioritize Quality Over Cost
The most critical factor in any HVAC project is the quality of the installation. Don’t compromise on contractor expertise just to save money. - Check for Rebates
Always research current rebates and incentives — they can significantly reduce your overall cost. - Compare Multiple Quotes
Request at least three estimates before making your choice. You can click here to get three free quotes from local professionals. These quotes include available rebates and tax credits and automatically exclude unqualified contractors. - Negotiate Smartly
Once you've chosen a contractor, use the proven strategies from our guide — How Homeowners Can Negotiate with HVAC Dealers — to get the best possible final price.