The HVAC Study Module 3
๐ฆ Module 3: Ductwork & Equipment Takeoffs
Build a complete HVAC ductwork + equipment takeoff with clean quantities, fitting counts, accessories, and schedule-driven equipment scope.
HVAC Estimating & Plan Reading CourseOverview
This module focuses on identifying, quantifying, and recording materials and labor for supply, return, exhaust, and ventilation systems, plus the equipment that drives them (AHUs, RTUs, VAVs, FCUs, fans). Youโll use plan/schedule data to structure a takeoff that flows directly into pricing.
๐ฏ Learning Objectives
- Classify duct by system, size, gauge/pressure class, liner/insulation, and shape (rect/round/oval).
- Separate straight duct LF vs. fittings counts with a repeatable method (no double-counts).
- Capture hangers/supports, access doors, dampers, insulation/lining, and flex connections.
- Extract equipment scope from schedules: CFM/ESP/tonnage, power, curb/rigging, and startup/TAB.
- Organize quantities into a structured spreadsheet ready for labor units and pricing.
๐ Duct Systems & Classification
System Types
- Supply (SA), Return (RA), Exhaust (EA), Outside Air (OA), Relief.
- Shapes: Rectangular, Round/Spiral, Oval.
- Attributes to record: size (WรH or ร), pressure class, gauge, liner/coating, insulation.
Pro tip: Keep System, Size, Gauge/Class, Liner, Insul as separate columns. Thatโs your QA backbone.
What Drives Cost
- Static pressure (ESP) → heavier gauge and more robust hangers/seismic.
- Large sizes → more SF, more labor per LF, increased fitting complexity.
- Liner/insulation → additional material SF and install time.
- Routing/height/congestion → productivity factors (ceiling tight, occupied, night work).
๐งญ Step-by-Step Takeoff Process
- Color-code by system: SA (blue), RA (orange), EA (green), OA (purple) on the plan layer.
- Trace mains/branches/risers: measure straight LF by size/class per segment.
- Count fittings: elbows (90/45), transitions, reducers, offsets, tees/wyes, taps, end caps.
- Add accessories: fire/smoke/volume dampers, access doors, backdraft dampers, flex, turning vanes.
- Supports: hangers/trapezes by spacing; seismic where required; sleeves at penetrations.
- Record insulation/liner by system/spec (thickness, type) & compute surface area.
- Equipment pass: locate AHUs/RTUs/FCUs/VAVs/fans; capture schedule fields and rigging/curbs.
- Log totals into the takeoff sheet with unique IDs for traceability.
Common misses: dampers at rated walls, access doors near coils/FD/SD, kitchen/hood exhaust distinctions, roof curb counts, flex length limits, and diffuser neck sizes vs. face sizes.
๐ Sample Takeoff Tables
Rectangular Duct Takeoff
| Area/Run | System | WรH (in) | Gauge / Class | Insul / Liner | LF | Notes |
|---|---|---|---|---|---|---|
| Level 2 โ Main | SA | 30ร18 | 24ga / 2" SP | 2" ext / 1" liner | 120 | Seismic bracing |
| Level 2 โ Branch A | RA | 18ร12 | 26ga / 1" SP | 1.5" ext | 85 | VAV taps ร 6 |
Fittings & Accessories
| Type | Size/Match | Qty | Labor Unit (hrs) | Notes |
|---|---|---|---|---|
| Elbow 90ยฐ | 30ร18 | 6 | โ | With turning vanes |
| Transition | 30ร18โ18ร12 | 4 | โ | Shop fab |
| Volume Damper | 18ร12 | 6 | โ | Manual quadrant |
| Fire/Smoke Damper | Wall @ Corr. | 3 | โ | Rated wall; access door |
| Access Door | 12ร12 | 5 | โ | Coils/dampers |
Supports & Hangers
| Run | LF | Assumed Spacing (ft) | Hangers (ea) | Notes |
|---|---|---|---|---|
| Level 2 โ Main | 120 | 8 | 15 | Trapeze @ majors |
| Branch A | 85 | 8 | 11 | Rod & strap |
Equipment Schedule Capture
| Tag | Type | CFM / Tonnage | ESP | Voltage / MCA | Weight | Curb/Pad | Notes |
|---|---|---|---|---|---|---|---|
| AHU-2 | AHU | 8,500 CFM | 2.5" | 480V / 42A | 1,150 lb | Curb-24x72 | Factory startup |
| RTU-5 | RTU | 12.5 ton | โ | 208V / 3ร | 1,900 lb | Roof curb | Crane pick |
Reminder: Capture startup/commissioning, TAB, vibration isolation, curbs/pads, rigging/crane and who owns which scope.
๐งฎ Mini Tools
๐ Rectangular Duct Surface Area
Surface Area (SF): โ
Per-LF area = 2ร(Wft + Hft). Use for insulation/liner material SF.
๐ Round Duct Surface Area
Surface Area (SF): โ
SF โ ฯ ร (D ft) ร LF.
๐งท Hanger Estimator
Hangers (ea): โ
Use project specs for true spacing; this is a planning aid.
โฑ๏ธ Fittings Labor (Quick Sum)
Fittings Labor (hrs): โ
Use your shopโs labor tables; these units are placeholders.
๐๏ธ Takeoff Workbook โ Column Mapping
| Takeoff Column | Description | Example |
|---|---|---|
| Area / Run | Drawing area or segment ID | L2 โ Main |
| System | SA / RA / EA / OA | SA |
| Size | Rect WรH or Round ร | 30ร18 |
| Gauge / Class | Metal gauge & pressure class | 24ga / 2" SP |
| Insul / Liner | Thickness/type | 2" ext / 1" liner |
| LF | Straight duct length | 120 |
| Fittings | El90, El45, Trans, Red, Tee, VD, FD/SD, AD, etc. | El90:6; Trans:4; VD:6 |
| Supports | Hangers/trapezes count | 15 |
| Notes | Seismic, clearances, access | Seismic bracing @ main |
| Rev/Add | Change tracking | Add 2 |
Integrate: Export your QTO to CSV and map into your labor/pricing template so updates flow with minimal rework.
๐งช QA/QC โ Last Look
- System coloring complete; no overlaps between SA/RA/EA layers.
- Straight LF reconciles with visual traces; risers captured on all floors.
- Fittings counted by size; transitions/reducers aligned with size changes.
- Dampers placed at rated walls/shafts; access doors added near each damper/coil.
- Hangers counted at assumed spacing; seismic allowances noted where required.
- Insulation/liner SF computed; diffusers/flex captured with length limits as specified.
- Equipment schedule fields (CFM/ESP/tonnage, power, weight, curb/pad) recorded; rigging/curb counts included.
- Revision/Addendum tag applied to changed quantities; filenames versioned.
๐ง Practice & Exit Ticket
- Take off one SA main and two branches; list LF by size and fittings by type.
- Compute rectangular and round surface area for two segments (use tools above).
- Estimate hangers for a 180 LF branch at 8' spacing + 10% extra; record count.
- Capture equipment data for one AHU and one EF: power, weight, curb/pad needs, startup.
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