HVAC Study Guide 2026

HSPF2 (Heating Seasonal Performance Factor 2) is the heating efficiency rating for heat pumps, measured over a full heating season. Higher values indicate better efficiency. Mini-splits typically achieve HSPF2 of 8-14+, significantly better than electric resistance heating (HSPF2 equivalent of 3.41).

Saturation temperature is the temperature at which a refrigerant changes between liquid and vapor states at a specific pressure.

Load calculation software (Manual J for residential, ASHRAE Handbook or HAP/Trace for commercial) calculates the heating and cooling loads for a specific building based on construction, climate, occupancy, and internal gains. Proper load calculations prevent over- or under-sizing equipment.

MERV (Minimum Efficiency Reporting Value, ASHRAE 52.2) rates particle removal efficiency. Commercial buildings require higher MERV filters (MERV 8-14) due to more occupants, regulatory requirements (ASHRAE 62.1), and higher expectations for air quality, despite the increased pressure drop.

The oil separator in a recovery machine removes compressor oil that may have mixed with the refrigerant during the recovery process, keeping the recovered refrigerant cleaner.

Superheat is the number of degrees the refrigerant vapor is heated above its saturation (boiling) temperature at a given pressure.