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BPA stresses Manual J sizing and duct verification to protect heat‑pump savings
Summary
BPA presenters emphasized Manual J calculations at design temperatures, duct external static pressure limits, and airflow verification to ensure heat pumps deliver predicted savings and avoid electric resistance backup.
Both presenters said correct equipment sizing and ductwork condition are major determinants of field performance. The project manager said ducts must be sealed and insulated and that undersized or leaky ducts will prevent lower‑temperature heat from reaching living spaces; Jamie Anthony said BPA will require contractors to supply Manual J sizing and document airflow and external static pressure to qualify for sizing and duct incentives.
Jamie Anthony explained the proposed sizing requirement: "We want you to show that at 20 degrees Fahrenheit, you can that the heat pump that you've picked can meet 100% of the load for that house in heat pump mode without electric resistance." He also described a duct test metric (external static pressure) with a proposed maximum of 0.8 inches of water to flag overly restrictive systems.
