Duct Calculator Elite

Added three more duct materials to the list, plus airflow in m³/h and the ASHRAE roughness value behind every material. The air temperature and elevation adjustment covers viscosity as well as density. NEW • Three more duct materials: phenolic (pre-insulated), galvanized spiral (corrugated), and flexible duct with an insulated helix core. The two fibrous glass liners now use ASHRAE's names. • Airflow in cubic meters per hour (m³/h). • Preferences shows the absolute roughness used for every material, from Table 1 of the 2025 ASHRAE Handbook — Fundamentals. Tap ⓘ where ASHRAE gives a range rather than a single number. • A flag on results where flow leaves the turbulent range and the published friction methods stop agreeing. NON-STANDARD AIR Sizing has always adjusted for your air temperature and elevation; this version lets air viscosity vary with your temperature too, as the ASHRAE Handbook prescribes for air outside the chart's range. Near sea level at ordinary temperatures nothing changes; higher or hotter, rates read 3–13% higher than in previous versions, the top of that range only where extreme heat and altitude combine. Your saved air temperature and elevation carry over unchanged; new installs now default the air temperature to 70 °F and the elevation to sea level. FIXED • A unit switch now re-checks the converted value against the new unit's range. • Pressure Drop accepts metric duct length up to 150 m.