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Heat Pump Balance Point

Screening estimate only—not equipment sizing or HVAC advice. Do not use this page to select equipment, disable backup heat, change controls, or assess safety. Capacity, COP, loads, and costs must come from sources appropriate to the exact building, equipment, conditions, and tariff. Qualified HVAC design should address the full system and climate.

Compare a simplified building load line with an editable piecewise-linear heat-pump capacity/COP curve.

Building and cost assumptions

Heat-pump curve points

Outdoor temperatureAvailable capacityCOP

Enter 2–20 points in strictly increasing temperature order. Capacity and COP are linearly interpolated only inside the entered temperature range; no extrapolation is reported.

Model and exclusions: Building heat load is a straight line equal to the entered design load at design temperature and zero at the entered heating-base temperature: load = design load × (base − outdoor)/(base − design), clamped to zero above base. Indoor temperature is retained as a reference and used only for the displayed design temperature difference; it does not replace the entered base-temperature model. Capacity and COP are independent linear interpolations between entered points. Heat-pump delivered-heat cost = electric $/kWh ÷ COP. Backup delivered-heat cost = fuel $/unit ÷ (entered efficiency × nominal kWh/unit). Nominal conversions here are 29.3001 kWh/therm, 26.8 kWh/US gal propane, and 40.7 kWh/US gal heating oil; confirm actual billing and fuel values. Defrost, crankcase/baseload electricity, fan/pump power, cycling, modulation, lockout, auxiliary staging, duct/piping losses, humidity, wind, solar/internal gains, thermal mass, climate bins, distribution temperature, part-load behavior, standby, demand charges, taxes, tiered/time-varying tariffs, fuel delivery fees, emissions, and equipment limits outside entered points are excluded.