What Region is used for the HSPF rating requirements for heat pump installations? Region 4 or 5?
The minimum HSPF rating requirements for all heat pump installations are based on Region 4, regardless of location. Unless otherwise specified, manufacturers’ published HSPF ratings and the HSPF ratings published in the Air-Conditioning, Heating, & Refrigeration Institute (AHRI) Directory of Certified Product Performance are based on Region 4. The ratings found in the AHRI directory can be used to fulfill program requirements.
HSPF ratings for Region 5 are sometimes referenced in regulations or shown in reference to a heat pump’s performance in a specific climate. Region 5 metrics come from equipment test data and cannot be directly converted to Region 4 metrics. Region 5 metrics can be requested from manufacturers, but Region 4 metrics should be used for program requirements.