Heat pump sizing in dwelling load calculations is governed by NEC 220.82(C)(6) under NEC 2023: when a heat pump serves both heating and cooling, include the heat pump compressor and the air handler at 100% of nameplate ratings — but do not include supplemental electric resistance heat simultaneously, as it is not likely to operate at the same time as cooling. Under the optional method, the largest HVAC load (typically the heat pump cooling) is included at 100%, with the understanding that heating and cooling will not operate simultaneously. This calculator correctly applies the heat pump demand factor rules for both standard and optional methods.
Heat pump dwelling: include the larger of heating or cooling. Cooling = 9,000 VA. Heating (compressor) = 12,000 VA. Use 12,000 VA for the heat pump at 100% per NEC 220.82(C)(6). Do not add supplemental strip heat unless it will operate simultaneously. Total optional method demand with 2,200 sq ft: ≈ 29,500 VA → 123A → 150A service.
This is a variant of the full Dwelling Load Calculator — which supports both the NEC standard and optional methods with all appliances, HVAC, and EV charger loads.
Try all options in the full Dwelling Load Calculator →