Static Pressure & Duct Check

Free, offline, no account. Read total external static pressure, check what an existing duct can actually move, size a new run, or design the whole system and export the schedule as a PDF. Every result shows what it assumed. Static Pressure & Duct Check is built for the retrofit and service call, not the drafting table. Most duct problems walk in as a static reading or a homeowner's hot room, and this app starts there. DIAGNOSE • Static Pressure Check — enter supply and return static plus the equipment's rated max and get total external static pressure (TESP), a clear over / within / under verdict, headroom, and which side carries more of the total. Probe-placement guidance for furnace-plus-coil and air-handler setups. • Duct Check — enter an as-built duct (round, rectangular, six materials, flex with compression) and read back the honest CFM range it can carry. Add a target airflow for an undersized / adequate / oversized verdict with friction rate and velocity. • No airflow number handy? Estimate CFM from tonnage right where you need it. SIZE A RUN • Quick Size — enter CFM and get the stocked duct size, round, rectangular, or flat-oval, with velocity and the governing constraint. Or scan the all-sizes table to see every candidate judged on friction and velocity. DESIGN A WHOLE SYSTEM (MANUAL D METHOD) • Walk Setup → Friction Rate → Runs → Summary and leave with a run-by-run duct schedule. • Static-pressure budget with honest defaults — an overridden default never masquerades as an assumption. • Size every trunk and branch: supply and return, flex with compression, altitude-corrected airflow. • In a hurry? Start from an assumed friction rate and refine when you have real numbers. SAVE, SHARE, DELIVER • Saved projects with automatic save — walk away mid-job, pick it up tomorrow. • Share any result by text, or export the Summary as a clean PDF or CSV for the homeowner, the inspector, or the office. • Light and dark mode. BUILT HONEST • Every result shows what it assumes, so you can sharpen it. • Plausibility checks flag implausible inputs as "check your inputs," never a confident wrong answer. • Stocked round sizes and role-based velocity limits reflect real-world practice. • Anything you share or export carries the same caveats you see on screen. PRIVATE BY DESIGN • Works fully offline. No sign-in, no cloud, no ads, no tracking. The numbers you enter and your saved projects never leave your phone. Anonymous usage counts (which screens are opened, never your numbers or job names) help us improve the app, and you can switch them off in Settings. Feedback goes out only when you tap send, and you see exactly what is included first. NEED THE PERMIT PACKAGE? Inspectors ask for a Manual J load calculation alongside the duct design. Our sister app, HVAC Load Calculator Manual J, produces that report; this app points you to it when a job calls for one. Static Pressure & Duct Check is a field estimator based on ACCA Manual D methods. It is a professional aid, not a substitute for a stamped Manual D design or measured commissioning.