Data imported from Manual S Selection:
Imported baseline: CFM • in. w.c. ESP •
Manual D baseline unlocked
CFM, ESP, and device losses were prefilled from the selected blower path.
Step 1: Environmental Baseline
Calculated per Manual J procedures.
Baseline: 20°F Cooling / 30-70°F Heating.
Cooling mode applies a wet-coil pressure multiplier. Heating mode keeps the entered coil value dry.
No Equipment Screening?
Screen Equipment & Airflow FirstIf entered, this value takes precedence over BTU/ΔT.
Auto-derived only when manual CFM is blank.
Step 2: Device Pressure Losses
Deduct the static pressure consumed by filters, coils, and grilles from the Blower ESP to find your Available Static Pressure (ASP).
Cooling mode applies a wet-coil factor to the entered coil pressure drop. Heating mode keeps the entered coil pressure drop in dry-coil condition.
Preset values are fixed reference benchmarks at 1200 CFM; enter manufacturer pressure drop at the actual design airflow when available.
*Using reference filter drop: IWC.
Available Static (ASP)
Step 3: Circulation Path (TEL)
Supply Side (Longest Run)
Equivalent Length AuditGeneric equivalent-length values are screening references. Use actual fitting data when available.
Return Side (Intake Run)
Generic equivalent-length values are screening references. Use actual fitting data when available.
Total Path Audit (TEL)
Terminal checks now use entered terminal CFM first, then inherit from a linked run when assigned, with system-CFM screening fallback preserved for backward compatibility.
Governing Total Effective Length (TEL)
Step 4: Critical Path, Validation & Sizing
Current Base Path
The fittings you selected in Step 3 automatically populate the first critical-path candidate.
Supply TEL / Return TEL / Total
Branch CFM Sanity Check
Assigned Runs
Assigned Total
System Airflow
Sanity Band
Leave blank for system-CFM screening. Assigned run CFMs are also summed against total system airflow.
Supply Candidate
Return Candidate
Critical Path Auto-Selection
Governing TEL
Round-Size Reference Output
Diagnostic Results Dashboard
System Friction & Performance Summary
Diagnostic Friction Rate
Preferred operating band: 0.06 to 0.18 in. w.c. / 100 ft.
Design CFM
Altitude Corrected
Available Static Pressure
Total Effective Length
Generic Fitting EL Map
Critical Path
System Warnings
Diagnostics Requiring Review
Reference Round-Size Check
Screening output
Pressure Budget Breakdown
ESP → DPL → ASP
Blower ESP
Component DPL
Available ASP
Governing Path Explanation
Why this path controls the design
System Snapshot
Project Block
Warnings & Errors
•
•
Technical Review
Manual D Screening Reference Context
This workflow follows Manual D® residential duct design relationships using upstream Manual J® load calculations and Manual S® equipment screening inputs. Results support structured screening of available static pressure (ASP), total equivalent length (TEL), and friction rate (FR) before final duct layout decisions.
Verify blower tables, manufacturer performance data, local code requirements, and project-specific field measurements before final installation or system balancing decisions.
HVAC Workflow Check
Confirm the upstream load and equipment before trusting duct screening.
Manual D screening depends on a reliable load basis, equipment airflow, and blower static pressure. Use these workflow checks when the duct result points back to load or equipment assumptions.
Step 1
Review load basis using Manual J Load Calculation .
Step 2
Screen equipment using Manual S Calculation .
Source Check
Verify source alignment in the Code Citations & Source Log .
HVAC Design Workflow
Load → Equipment → Duct Screening
Duct screening depends on both calculated system load (Manual J) and screened equipment airflow characteristics (Manual S). Use this tool to flag distribution constraints based on those upstream design decisions.
Manual D Screening Badge
Primary issue:
Review load basis using Manual J Load Calculation .
Return with Manual D screening status, primary issue, and governing path context.Screen equipment using Manual S calculation .
Return with Manual D airflow screening so equipment screening can be reviewed against duct restrictions.Manual D Screening Reference
How This Duct Screening Result Is Determined
The screening result is based on available static pressure, total effective length, friction rate, and generic fitting equivalent-length references. These checks help identify pressure-budget and duct-path risks before final Manual D design review.
Governing Formulas
Available Static Pressure
ASP = ESP - (Coil DPL + Filter DPL + Grille DPL)
ASP is the remaining blower static pressure after external device losses are deducted.
Friction Rate
FR = (ASP × 100) / TEL
FR estimates how much pressure is available per 100 feet of effective duct path.
Generic Fitting Equivalent-Length Reference
| Common Fitting Type | Reference EL (ft) |
|---|---|
| 90° round elbow | 20–35 |
| Wye branch | 25–40 |
| Plenum-to-round collar | 35 |
| Standard supply boot | 30 |
These equivalent-length values are generic screening references. Verify fitting losses against the actual fitting geometry, radius, entry condition, and manufacturer or project data before final duct layout.