# Dual-fuel heat pumps: thermal and economic balance points

Canonical: https://www.savpwr.com/knowledge/dual-fuel-balance-point
Market: United States
Author: SAVPWR Editorial (VDX Logic LLC)
Published: 2026-11-09
Sources checked: 2026-11-09

## What does a heat-pump balance point mean?

The thermal balance point concerns heating capacity versus building load. An economic crossover concerns the relative operating cost of heat sources. They are different questions and do not necessarily occur at the same outdoor temperature.

## Capacity crossover

As conditions change, the house heating load and heat-pump capacity can move in different directions. A design compares the two curves to identify when supplementary capacity is needed. Manufacturer data and a load calculation support that decision. [1]

## Cost crossover

Relative cost depends on electricity and fuel tariffs, furnace efficiency and the heat pump’s temperature-specific COP. A fixed rule such as always switch at 35°F ignores those differences. Controls must also respect the equipment’s approved operating and safety requirements. [1][2]

## Ask for a control narrative

Request a plain-language statement of what runs above and below the selected changeover conditions, whether simultaneous operation is allowed, and how defrost or emergency operation is handled. Have the installer document final settings so later service does not unknowingly change the intended strategy.

## Decision exercise

With electricity at $0.24/kWh, gas at $1.80/therm and assumed furnace efficiency 0.90, the simplified equal-cost COP is about 3.52: 293.1 × 0.24 × 0.90 / (10 × 1.80). This is an economic threshold under stated assumptions, not an outdoor-temperature setting or a complete control design.

Numbers are illustrative assumptions, not forecasts.

## Preparation checklist

- Ask whether the proposed threshold is thermal or economic.
- Use current tariffs and temperature-specific performance.
- Keep final control settings with the equipment records.

## Can I determine a changeover temperature from HSPF2 alone?

No. A seasonal rating does not provide a complete temperature-specific performance curve or control design.

## Sources

[1] PNNL — Cold Climate Heat Pump Sizing and Selection: https://basc.pnnl.gov/resource-guides/cold-climate-heat-pump-sizing-and-selection
[2] DOE Building Science Education — Programmable Thermostats: https://bsesc.energy.gov/energy-basics/hvac-programmable-thermostats

AI-assisted preparation; no licensed professional review is claimed. Editorial policy: https://www.savpwr.com/editorial