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HVAC made simple
Heat Pump Auxiliary Heat Cost Calculator
Estimate how much auxiliary heating costs, compare electric or gas backup with heat pump operation, and understand the potential impact on your winter energy bills.
What Is Auxiliary Heat?
Auxiliary heat supplements your heat pump when additional heating is needed. Electric resistance strips are common in all-electric systems, while some dual-fuel systems use a gas furnace for backup. Auxiliary heating is not automatically a problem, but frequent use can increase operating expenses.
1. Auxiliary Heating System
For electric heat strips, enter their electrical input in kilowatts. For gas backup, enter the furnace’s fuel input rating in BTU/hr, not its delivered heat output.
2. Electricity & Fuel Prices
The blower field represents only electrical power used in addition to the auxiliary heat input, or power that would otherwise be excluded. Avoid counting the same fan electricity twice.
3. Heating Season & Usage
About COP: Coefficient of Performance (COP) measures how much heat a heat pump delivers per unit of electricity. A COP of 2.2 means approximately 2.2 kWh of heat is delivered for every 1 kWh of electrical input. Use an estimate appropriate for the outdoor temperatures when auxiliary heating operates.
4. Optional Savings Scenario
This scenario assumes the reduced auxiliary heat is replaced by equivalent useful heating from the compressor at the entered COP. It is only feasible if the heat pump has enough available capacity under those conditions.
YOUR AUXILIARY HEATING COST ESTIMATE
Estimated Heating Expenses
Seasonal Auxiliary Heating Cost
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Estimated fuel and applicable electricity costs
Estimated Additional Cost vs. Heat Pump
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Equivalent delivered heat comparison
Hourly Auxiliary Cost
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Daily Auxiliary Cost
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Monthly Auxiliary Cost
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Seasonal Runtime
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Seasonal Cost Comparison
Auxiliary Heating
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Heat Pump Compressor Equivalent
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Both estimates are based on delivering the same amount of useful heat. This is a hypothetical comparison, not a guarantee that the compressor can replace all auxiliary operation.
Heating Energy & Operating Details
Useful Heating Output
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Seasonal Heat Delivered
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Auxiliary Energy Consumption
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Equivalent Heat Pump Electricity
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Potential Savings From Reduced Auxiliary Runtime
Estimated Seasonal Net Savings
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This estimate subtracts the additional compressor electricity required to replace the reduced backup heating. Actual savings may differ due to capacity limitations, defrost behavior, thermostat controls, and changing weather.
Understanding Your Results
Ways to Manage Auxiliary Heating Costs
How to Use This Auxiliary Heat Cost Calculator
Choose your backup heating type, enter its capacity and estimated daily runtime, and provide your local utility prices. Then specify how frequently auxiliary heating operates during the heating season. The calculator estimates the associated energy expenses and compares them with the theoretical cost of delivering equivalent heat using the heat pump compressor.
Why Does Auxiliary Heat Increase Electricity Bills?
Electric resistance heating typically converts approximately one unit of electricity into one unit of heat, while a heat pump transfers heat and can deliver multiple units of heating for each unit of electricity consumed. Consequently, electric heat strips often cost more to provide the same heating output. However, backup heat may be necessary during extreme weather, defrost cycles, or when the heat pump cannot meet the home’s heating load on its own.
Is Auxiliary Heat Always Expensive?
Not necessarily. Operating cost depends on the backup fuel, electricity rates, equipment efficiency, and outdoor conditions. A dual-fuel system with a gas furnace may sometimes provide lower-cost heat than compressor operation, particularly at low temperatures. The calculator helps illustrate these differences using your assumptions.