Heat Pump Design Workflow

After completing Manual J, open the heat pump design workflow. Select a candidate heat pump from the equipment database. The balance point graph plots the building load line (from zero at setpoint to peak load at design temperature) against the heat pump capacity curve.

The balance point temperature is highlighted — this is where supplemental heat activates. If the balance point is above your heating design temperature, the graph shows the supplemental capacity gap at design conditions.

The COP chart shows Coefficient of Performance at each outdoor temperature for your selected equipment. Combined with local temperature bin data (hours per year at each temperature), this calculates seasonal COP — a much more accurate efficiency metric than the HSPF rating alone.

Enter your local electricity rate ($/kWh) and gas rate ($/therm) to see annual heating cost comparisons: heat pump only, gas furnace only, and dual-fuel with optimized switchover.

For inverter-driven heat pumps, the capacity range is shown as a band rather than a single line. The graph shows minimum and maximum capacity at each temperature, with the building load line crossing through the band.

The operating point analysis shows where the unit will modulate at each outdoor condition — helpful for verifying the unit won't short-cycle on mild days (minimum capacity too high for the load) or max out too early on cold days.